mm ■ ■hKm BmBB BWwB ■DHT ■■ B^DBHRHSKSM ■mhmhbpeh ■ _~BIMMWagWftMBl ■BHH mwrc ■ Ml i m SSfe WW WW "VH ^m HBHG ■■HH Hi ^b^H HMfli mm HE I H ' tB3R ■n ■■ ■ ]hh - IBBfl UK Bffl mh mmiiWiiiHH hh ■miiiiiiiiB ■■a ■ ■■fl WFBHBflf gl DHSI ■ ■ Baa MfflKtff ■ffBi 88s ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■^■^^ ■ ci> ^ A^ - A 'U : A°^ * : v. o V^ vv oS"' tf '^ 1,0 o. ■ $■ ■*+, >". -A N % * -, A ,^ A A .j\. '> A >• 'A *>. * o v v° <, > A* % \ X ^" v > ^y '• ^ v '^- -v, ^ REPORT of DRAFT GEAR TESTS United States Railroad Administration Inspection and Test Section Preface by C. B. YOUNG, Manager Inspection and Test Section, Division of Operation, United States Railroad Administration Published by the Simmons-Boardman Publishing Company NEW YORK 1921 TF4-I3 •XL (*5* 401 7 ld2i CONTENTS Page Draft Gear Tests of the United States Railroad Administration, Inspection and Test Section 1 Draft Gear Testing 3 Test Program 6 Description of Gears 7 Westinghouse Type D-3, Gears No. 1, 2 and 3 7 Westinghouse Type NA-1, Gears No. 4, 5, 6, 7 and 8 8 Sessions Type K, Gears No. 9, 10, 11 and 12 9 Sessions Jumbo, Gears No. 13, 14 and 15 10 Cardwell Type G-25-A, Gears No. 16, 17 and 18 11 Cardwell Type G-18-A, Gears No. 19, 20 and 21 12 Miner Type A-18-S, Gears No. 22, 23 and 24 13 Miner Type A-2-S, Gears No. 25, 26 and 27 14 National Type H-l, Gears No. 28, 29 and 30 15 National Type M-l, Gears No. 31, 32 and 33 16 National Type M-4, Gears No. 34, 35 and 36 17 Murray Type H-25, Gears No. 37, 38 and 39 17 Gould Type 175, Gears No. 40, 41 and 42 19 Bradford Type K, Gears No. 43, 44, 45, 46 and 47 20 Waugh Plate Type, Gears No. 48, 49 and 50 21 Christy, Gears No. 51, 52 and 53 21 Harvey Friction Springs, Gears No. 54, 55 and 56 23 A. R. A. Class G Springs, Gears No. 57, 58 and 59 23 Selection and Condition of Test Gears 24 Westinghouse D-3, Gears No. 1, 2 and 3 24 Westinghouse NA-1, Gears No. 4, 5, 6, 7 and 8 24 Sessions K, Gears No. 9, 10, 11 and 12 24 Sessions Jumbo, Gears No. 13, 14 and 15 25 Cardwell G-25-A, Gears No. 16, 17 and 18 25 Cardwell G-18-A, Gears No. 19, 20 and 21 25 Miner A-18-S, Gears No. 22, 23 and 24 25 Miner A-2-S, Gears No. 25, 26 and 27 25 National H-l, Gears No. 28, 29 and 30 26 National M-l, Gears No. 31, 32 and 33 26 National M-4, Gears No. 34, 35 and 36 26 Murray H-25, Gears No. 37, 38 and 39 26 Gould 175, Gears No. 40, 41 and 42 26 Bradford K, Gears No. 43, 44, 45, 46 and 47 26 Christy, Gears No. 51, 52 and 53 27 Harvey Friction Springs, 8 in. x 8 in., Gears No. 54, 55 and 56 27 A. R. A. Class G Springs, Gears No. 57, 58 and 59 27 9,000 Lb. Drop Tests 29 Westinghouse D-3, Gears No. 1, 2 and 3 30 Westinghouse NA-1, Gears No. 4, 5, 6, 7 and 8 30 Sessions K, Gears No. 9, 10, 11 and 12 30 Sessions Jumbo, Gears No. 13, 14 and 15 30 Cardwell G-25-A, Gears No. 16, 17 and 18 30 Cardwell G-18-A, Gears No. 19, 20 and 21 31 V Page Miner A-18-S, Gears No. 22, 23 and 24 31 Miner A-2-S, Gears No. 25, 26 and 27 31 National H-l, Gears No. 28, 29 and 30 31 National M-l, Gears No. 31, 32 and 33 31 National M-4, Gears No. 34, 35 and 36 31 Murray H-25, Gears No. 37, 38 and 39 32 Gould 175. Gears No. 40, 41 and 42 . 32 Bradford K, Gears No. 43, 44, 45, 46 and 47 32 Waugh Plate Type, Gears No. 48, 49 and 50 32 Christy, Gears No. 51, 52 and 53 32 Harvey 8 in. x 8 in. Springs, Gears No. 54, 55 and 56 32 A. R. A. Class G Springs, Gears No. 57, 58 and 59 33 Summary of 9,000 lb. Drop Tests 33 Static Tests 36 Westinghouse D-3, Gears No. 1 and 2 37 Westinghouse NA-1, Gears No. 4 and 5 . . 37 Sessions K, Gears No. 9 and 10 37 Sessions Jumbo, Gears No. 13 and 14 38 Cardwell G-25-A, Gears No. 16 and 17 38 Cardwell G-18-A, Gears No. 19 and 20 38 Miner A-18-S, Gears No. 22 and 23 , 38 Miner A-2-S, Gears No. 25 and 26 38 National H-l, Gears No. 28 and 29 38 National M-l, Gears No. 31 and 32 39 National M-4, Gears No. 34 and 35 39 Murray H-25, Gears No. 37 and 38 39 Gould 175, Gears No. 40 and 41 39 Bradford K, Gears No. 45 and 46 39 Waugh Plate Type, Gears No. 48 and 49 39 Christy, Gears No. 51 and 52 39 Harvey 8 in. x 8 in. Springs, Gears No. 54, 55 and 56 40 A. R. A. Class G Springs, Gears No. 57, 58 and 59 40 Summary of Static Tests 40 9,000 Lb. Drop Tests, Friction Surfaces Coated with Foreign Material 62 Destructive Tests 66 Westinghouse D-3!, Gear No. 1 66 Westinghouse NA-1, Gear No. 6 66 Sessions K, Gear No. 10 ' 67 Sessions Jumbo, Gear No. 13 67 Cardwell G-25-A, Gear No. 16 67 Cardwell G-18-A, Gear No. 19 67 Miner A-18-S, Gear No. 22 68 Miner A-2-S, Gear No. 25 68 National H-l, Gear No. 28 68 National M-l, Gear No. 31 69 National M-4, Gear No. 34 69 Murray H-25, Gear No. 37 69 Gould 175, Gear No. 40 69 VI Page Bradford K, Gear No. 45 70 Waugh Plate Type, Gear No. 48 70 Christy, Gear No. 51 70 Harvey Springs, Gear No. 54 70 A. R. A. Class G Springs, Gear No. 57 70 Summary of Destructive Tests 72 Rivet Shearing Tests 73 Car-Impact Tests 79 The Symington Test Plant 79 Action of Cars During Impact 83 Records in Car-Impact Tests 87 Impact Velocity 88 Travel of Cars Along Track 88 Draft Gear Travel and Action 88 Seismograph Readings 89 Graphs of Car Action 91 Making a Test Run 91 Study of Curves 99 Car-Movement Curves — Superimposed 99 Velocity Curves 100 Energy Curves • 102 Time-Force Curves 103 Time-Closure Curves 105 Force-Closure Curves 105 Solid Buffer Runs 106 Discussion of Gears in Car-Impact Tests Ill National H-l, Gear No. 29 in Car B, Gear No. 30, or Solid Buffer, in Car A Ill Sessions Type K, Gear No. 11 in Car B, Gear No. 12, or Solid Buffer, in Car A .- Ill Miner A-18-S, Gear No. 23 in Car B, Gear No. 24, or Solid Buffer, in Car A 112 Westinghouse NA-1, Gear No. 7 in Car B, Gear No. 8, or Solid Buffer, in Car A 112 National M-l, Gear No. 32 in Car B, Gear No. 33, or Solid Buffer, in Car A 113 Sessions Jumbo, Gear No. 14 in Car B, Gear No. 15, or Solid Buffer, in Car A 113 National M-4, Gear No. 35 in Car B, Gear No. 36, or Solid Buffer, in Car A 114 Cardwell G-18-A, Gear No. 20 in Car B, . . Gear No. 21, or Solid Buffer, in Car A 114 Cardwell G-25-A, Gear No. 17 in Car B, Gear No. 18, or Solid Buffer, in Car A 114 Westinghouse D-3, Gear No. 2 in Car B, Gear No. 3, or Solid Buffer, in Car A 115 Gould 175, Gear No. 41 in Car B, Gear No. 42, or Solid Buffer, in Car A '. . . 115 VIT Murray H-25, Gear No. 38 in Car B, Page Gear No. 39, or Solid Buffer, in Car A 115 Christy, Gear No. 52 in Car B, Gear No. 53 or Solid Buffer in Car A 116 Miner A-2-S,. Gear No. 26 in Car B, Gear No. 27, or Solid Buffer, in Car A 116 Waugh Plate Type, Gear No. 49 in Car B, Gear No. 50, or Solid Buffer, in Car A 117 Bradford K, Gear No. 46 in Car B, Gear No. 47, or Solid Buffer, in Car A 117 Harvey Springs, Gear No. 55 in Car B, Gear No. 56, or Solid Buffer, in Car A 118 Class G Coil Springs, Gear No. 58 in Car B, Gear No. 59, or Solid Buffer, in Car A 118 Summary of Car-Impact Tests 119 Comparison of the Different Methods of Testing 129 General Deductions 132 Results to be Expected from Commercial Gears 134 Grading of Average Commercial Gears 139 Capacity 139 Smoothness of Action 139 Ultimate Force or Closing Pressure 139 Absorption 140 Over-Solid Sturdiness 140 Workmanship and General Operation 140 Service Performance of Gears 140 State of Development of Gears ". 140 Service Tests 142 Train-Operation Tests 143 Tests of Draft Gear Attachments 143 Appendices Appendix A. Report of Draft Gear Test Made on Norfolk & Western Railroad, November 4, 1918 269 Object of Test 269 Equipment Used 269 Preparation of Draft Gears 269 Recording Apparatus 270 Discussion of Cards 271 General 271 Appendix B. Tests of Car Construction 275 Test No. 1— Wood Draft Sills 275 Test No. 2r— Metal Draft Arms 276 Test No. 3 — Draft Attachments with Central Stop Casting 277 Condition of Cars 278 Condition of Coupler and Draft Attachments 278 Test No. 4 — Attachments with Separate and Independent Draft Lugs 279 Condition of Cars 280 Condition of Coupler and Attachments 280 VIII LIST OF ILLUSTRATIONS Fig. No. Page 1 Identification of Gears in Test : 6 2 Westinghouse D-3 Gear 7 3 Westinghouse NA-1 Gear 8 4 Sessions Type K Gear 10 5 Sessions Jumbo Gear 11 6 Cardwell Type G-25-A Gear 12 7 Miner Type A-18-S Gear 13 8 Miner Type A-2-S Gear 15 9 National Type M-l Gear 17 10 Murray Type H-25 Gear 18 11 Gould Type 175 Gear 19 12 Bradford Type K Gear 20 13 Waugh Plate Gear 21 14 Christy Gear 22 15 Harvey Friction Springs 23 16 Comparative Performance of Gears in Drop Tests 34, 35 17 Comparative Ultimate Resistance of Gears 42, 43 18 Drop Test and Static Test Diagrams, Westinghouse Type D-3 44 19 Drop Test and Static Test Diagrams, Westinghouse Type NA-1 45 20 Drop Test and Static Test Diagrams, Sessions Type K 46 21 Drop Test and Static Test Diagrams, Sessions Jumbo 47 22 Drop Test and Static Test Diagrams, Cardwell Type G-25-A 48 23 Drop Test and Static Test Diagrams, Cardwell Type G-18-A 49 24 Drop Test and Static Test Diagrams, Miner Type A-18-S 50 25 Drop Test and Static Test Diagrams, Miner Type A-2-S 51 26 Drop Test and Static Test Diagrams, National Type H-l 52 27 Drop Test and Static Test Diagrams, National Type M-l 53 28 Drop Test and Static Test Diagrams, National Type M-4 54 29 Drop Test and Static Test Diagrams, Murray Type H-25 55 30 Drop Test and Static Test Diagrams, Gould Type 175 56 31 Drop Test and Static Test Diagrams, Bradford Type K 57 IX Fig. No. p AGE 32 Drop Test and Static Test Diagrams, Waugh Plate Gear 58 33 Drop Test and Static Test Diagrams, Christy Draft Gear 59 34 Drop Test and Static Test Diagrams, Harvey Friction Springs 60 35 Drop Test and Static Test Diagrams, A. R. A. Class G Springs 6L 36 Performance of Gears with Coated Friction Surfaces (Drop Test) 63 37 Drop Tests of Friction Gears Which Were Taken Out of Service, Norfolk & Western Railway 64 38 Performance of Gears in Destructive Tests 71 39 Results of i/ 2 in. Rivet Shearing Tests. Draft Gears for U. S. R. A. Cars. 9,000-lb. Drop 74 40 Performance of Gears in V 2 in. Rivet Shearing Tests. 9,000-lb. Drop . . 75 41 Diagrams of Rivet Shearing Action of Draft Gears 77 42 General View of Symington Gravity Test Plant 80 43 General Profile of Test Track 81 44 Enlarged Profile of Test Track for 90 ft 82 45 Enlarged Profile for 12-in. Movement of Car A 83 46 Enlarged Profile for 12-in. Movement of Car B 83 47 General View of Car B and Its Lading 84 48 Farlow Two-Key Draft Gear Attachments Used on Test Cars 85 49 Instrument on Car B for Recording Draft Gear Action 90 50 Specimen Time-Closure Curve Produced on Small Drum of Car B . . . . 89 51 Seismograph of Car A 91 52 Instrument for Recording Car Action 92 53 Another View of Instrument for Recording Car Action 93 54 Specimen Car-Movement Card from Drum A 95 55 Specimen Car-Movement Card from Drum B 95 56 Specimen Car-Movement Cards from Drums A and B Superimposed. . 97 57 Mechanical Differentiating Machine 103 58 Curves from Solid Buffer Runs 108 59 Plot of Car Body Yield at Varying Impact Velocities 109 60 Plot of Force at Varying Impact Velocities 110 61 Tabulation of Closing Speeds of Gears; Car-Impact Tests 121 62 Tabulation of Car-Impact Tests — Closing Speed Runs. Double Gear Tests, 143,000-lb. Cars 122, 123 63 Tabulation of Car-Impact Tests, One-Mile-Per-Hour Runs. Double Gear Tests 124, 125 X Fig. No. Page 64 Tabulation of Car-Impact Tests, Closing Speed Runs. Single Gear Tests, 143,000-lb. Cars 126, 127 65 Comparison of Double Gear and Single Gear Action. Car Impact Tests. 143,000-lb. Cars 128 66 Comparison of Work Done and Work Absorbed by Test Gears in Static, Drop and Car-Impact Tests 131 67 Comparative Performance of Commercial Gears, Showing Average Re- sults that may be Expected from New Gears of Each Type . . . 136, 137 68 Energy Curves for Cars of Various Weights, with Commerical Gear Capacities Indicated 138 69 Grading of Gears, Based Upon Performance of New Commercial Gears 141 70 List of and Index of Car-Movement Curves and Derivative Curves, Em- bracing Figs. 71 (a to t) to 88 (a to t) Inclusive 144 71a Car-Movement Curves, Superimposed, National H-l Gears 145 71b-c Car-Movement Curves, Superimposed, National H-l Gears 146 71d-e-f Velocity Curves, National H-l Gears 147 71g-j Energy Curves, National H-l Gears 148 71k-m Time-Force Curves, National H-l Gears 149 71n-q Time-Closure Curves, National H-l Gears 150 71r-t Force-Closure Diagrams, National H-l Gears 151 72a Car-Movement Curves, Superimposed. Sessions K Gears 152 72b-c Car-Movement Curves, Superimposed. Sessions K Gears 153 72d-e-f Velocity Curves, Sessions K Gears '. 154 72g-j Energy Curves, Sessions K Gears 155 72k-m Time-Force Curves, Sessions K Gears 156 72n-p-q Time-Closure Curves, Sessions K Gears 157 72r-t Force-Closure Diagrams, Sessions K Gears 158 73a Car-Movement Curves, Superimposed. Miner A-18-S Gears 159 73b-c Car-Movement Curves, Superimposed. Miner A-18-S Gears 160 73d-e-f Velocity Curves, Miner A-18-S Gears 161 73g-j Energy Curves, Miner A-18-S Gears 162 73k-m Time-Force Curves, Miner A-18-S Gears 163 73n-p-q Time-Closure Curves, Miner A-18-S Gears 164 73r-t Force-Closure Diagrams, Miner A-18-S Gears 165 74a Car-Movement Curves, Superimposed. Westinghouse NA-1 Gears . . . 166 74-b-c Car-Movement Curves, Superimposed. Westinghouse NA-1 Gears.... 167 XI Fig. No. Page 74d-e-f Velocity Curves, Westinghouse NA-1 Gears 168 74g-j Energy Curves, Westinghouse NA-1 Gears 169 74k-m Time-Force Curves, Westinghouse NA-1 Gears 170 74n-q Time-Closure Curves, Westinghouse NA-1 Gears 171 74r-t Force-Closure Diagrams, Westinghouse NA-1 Gears 172 75a Car-Movement Curves, Superimposed, National M-l Gears 173 75b-c Car-Movement Curves, Superimposed. National M-l Gears 174 75d-e-f Velocity Curves, National M-l Gears 175 75g-j Energy Curves, National M-l Gears 176 75k-m Time-Force Curves, National M-l Gears 177 75n-q Time-Closure Curves, National M-l Gears 178 75r-t Force-Closure Diagrams, National M-l Gears 179 76a Car-Movement Curves, Superimposed. Sessions Jumbo Gears 180 76b-c Car-Movement Curves, Superimposed. Sessions Jumbo Gears 181 76d-e-f Velocity Curves, Sessions Jumbo Gears 182 76g-j Energy Curves, Sessions Jumbo Gears 183 76k-m Time-Force Curves, Sessions Jumbo Gears 184 76n-p-q Time-Closure Curves, Sessions Jumbo Gears 185 76r-t Force-Closure Diagrams, Sessions Jumbo Gears 186 77a Car-Movement Curves, Superimposed. National M-4 Gears . 187 77b-c Car-Movement Curves, Superimposed. National M-4 Gears 188 77d-e-f Velocity Curves, National M-4 Gears 189 77g-j Energy Curves, National M-4 Gears 190 77k-m Time-Force Curves, National M-4 Gears 191 77n-q Time-Closure Curves, National M-4 Gears 192 77r-t Force-Closure Diagrams, National M-4 Gears 193 78a-b Car-Movement Curves, Superimposed. Cardwell G-18-A Gears 194 78c Car-Movement Curves, Superimposed. Cardwell G-18-A Gears 195 78d-e-f Velocity Curves, Cardwell G-18-A Gears 196 78g-j Energy Curves, Cardwell G-18-A Gears 197 78k-m Time-Force Curves, Cardwell G-18-A Gears 198 78n-q Time-Closure Curves, Cardwell G-18-A Gears 199 78r-t Force-Closure Diagrams, Cardwell G-18-A Gears 200 79a Car-Movement Curves, Superimposed. Cardwell G-25-A Gears 201 XII Fig. No. Page 79b-c Car-Movement Curves, Superimposed. Cardwell G-25-A Gears 202 79d-e-f Velocity Curves, Cardwell G-25-A Gears 203 79g-h-j Energy Curves, Cardwell G-25-A Gears 204 79k-l-m Time-Force Curves, Cardwell G-25-A Gears 205 79n-p-q Time-Closure Curves, Cardwell G-25-A Gears 206 79r-s-t Force-Closure Diagrams, Cardwell G25-A Gears 207 80a Car-Movement Curves, Superimposed. Westinghouse D-3 Gears 208 80b-c Car-Movement Curves, Superimposed. Westinghouse D-3 Gears .... 209 80d-e-f Velocity Curves, Westinghouse D-3 Gears 210 80g-h-j Energy Curves, Westinghouse D-3 Gears 211 80k-l-m Time-Force Curves, Westinghouse D-3 Gears 212 80n-p-q Time-Closure Curves, Westinghouse D-3 Gears 213 80r-s-t Force-Closure Diagrams, Westinghouse D-3 Gears 214 81a Car-Movement Curves, Superimposed. Gould No. 175 Gears 215 81b-c Car-Movement Curves, Superimposed. Gould No. 175 Gears 216 81d-e-f Velocity Curves, Gould No. 175 Gears 217 81g-h-j Energy Curves, Gould No. 175 Gears 218 81k-l-m Time-Force Curves, Gould No. 175 Gears 219 81n-p-q Time-Closure Curves, Gould No. 175 Gears 220 81r-s-t Force-Closure Diagrams, Gould No. 175 Gears 221 82a Car-Movement Curves, Superimposed. Murray H-25 Gears 222 82b-c Car-Movement Curves, Superimposed. Murray H-25 Gears 223 82d-e-f Velocity Curves, Murray H-25 Gears 224 82g-h-j Energy Curves, Murray H-25 Gears 225 82k-l-m Time-Force Curves, Murray H-25 Gears 226 82n-p-q Time-Closure Curves, Murray H-25 Gears 227 82r-t-s Force-Closure Diagrams, Murray H-25 Gears 228 83a Car-Movement Curves, Superimposed. Christy Gears 229 83b-c Car-Movement Curves, Superimposed. Christy Gears 230 83d-e-f Velocity Curves, Christy Gears 231 83g-j Energy Curves, Christy Gears 232 83k-m Time-Force Curves, Christy Gears 233 83n-q Time-Closure Curves, Christy Gears 234 83r-t Force-Closure Diagrams, Christy Gears 235 84a Car-Movement Curves, Superimposed. Miner A-2-S Gears 236 XIII Fig. No. Page 84b-c Car-Movement Curves, Superimposed. Miner A-2-S Gears 237 84d-e-f Velocity Curves, Miner A-2-S Gears 238 84g-j Energy Curves, Miner A-2-S Gears 239 84k-m Time-Force Curves, Miner A-2-S Gears 240 84n-p-q Time-Closure Curves, Miner A-2-S Gears 241 84r-t Force-Closure Diagrams, Miner A-2-S Gears 242 85a-b-c Car-Movement Curves, Superimposed. Waugh Plate Gears 243 85d-e-f Velocity Curves, Waugh Plate Gears 244 85g-j Energy Curves, Waugh Plate Gears 245 85k-m Time-Force Curves, Waugh Plate Gears 246 85n-p-q Time-Closure Curves, Waugh Plate Gears 247 85r-t Force-Closure Diagrams, Waugh Plate Gears 248 86a-b-c Car-Movement Curves, Superimposed. Bradford K Gears 249 86d-e-f Velocity Curves, Bradford K Gears 250 86g-j Energy Curves, Bradford K Gears 251 86k-m Time-Force Curves, Bradford K Gears 252 86n-p-q Time-Closure Curves, Bradford K Gears 253 86r-t Force-Closure Diagrams, Bradford K Gears 254 87a-b-c Car-Movement Curves, Superimposed, Harvey Springs 255 87d-e-f Velocity Curves, Harvey Springs 256 87g-j Energy Curves, Harvey Springs 257 87k-m Time-Force Curves, Harvey Springs 258 87n-p-q Time-Closure Curves, Harvey Springs 259 87r-t Force-Closure Diagrams, Harvey Springs 260 88b-c Car-Movement Curves, Superimposed. A. R. A. Class G Springs 261 88e-f Velocity Curves, A. R. A. Class G Springs 262 88j Energy Curve, A. R. A. Class G Springs 263 88m Time-Force Curves, A. R. A. Class G Springs 263 88p-q Time-Closure Curves, A. R. A. Class G Springs 264 88t Force-Closure Diagram, A. R. A. Class G Springs 265 89-1 Summary Curves, Westinghouse D-3 Gears 266 89-2 Summary Curves, Westinghouse D-3 Gears 267 89-3 Summary Curves, Westinghouse D-3 Gears 268 Chronographic Records of Draft Gear Action in Train Service, Norfolk & Western Railway 273, 274 XIV PREFACE When the United States Railroad Administration decided in the spring of 1918 to enter upon its car and locomotive building program, one of the problems which early came before the Com- mittee on Standards for Locomotives and Cars and the Central Advisory Purchasing Committee was the selection of draft gears to be used and the allocation of orders among the several manu- facturers. The Committee on Standards and the Purchasing Section were both embarrassed, owing to a lack of definite and positive knowledge as to the relative merits of the different gears as well as the relation between mechanical value and cost. Much information on the subject of draft gears was presented by the various manufacturers, but a comparison of the information presented soon developed the fact that each manufacturer had prepared his information on a basis of his own selection and that it was impossible to correlate or co-ordinate the various tests in any comparable manner. The reports of the Draft Gear Committee of the Master Car Builders' Associa- tion and the files of the mechanical associations failed to give any definite information on the subject. In the absence of real information, the Committee on Standards adopted the wording of the M.C.B. specification for draft gears for Class III and Class IV tank cars which provides that the gears purchased shall have a "minimum capacity of 150,000 lb." The committee later defined this requirement in the following words: "A 150,000 lb. draft gear should be defined as one that will sustain a drop of 16 in. (including travel of the gear) of a 9,000 lb. weight without shearing the rivets of one or both lugs which are to be secured to suitable members by nine V2 in. rivets of .15 carbon or under, driven in -ft in. holes." When gears were tested under this requirement, it was found that no useful information was obtained. Gears of widely varying characteristics and excellence passed the prescribed test and it was soon appreciated that the specification requirement as well as this test were useless in obtaining draft gear information. When this absolute dearth of reliable knowledge on the subject was fully realized by the Committee on Standards and the Purchasing Committee, they joined in requesting the Inspection and Test Section of the Division of Operation to conduct such a series of tests as would determine the mechanical value of each make and type of friction draft gear then regularly offered for sale to railroads. In addition to the various tests which have been completed and which are given in the report, the Section had definite plans made for train operation tests and service tests. Had the time been available and had circumstances permitted, the Section would have completed these tests. It is much to be regretted that conditions on the railroads throughout the country during the war and immediately thereafter prevented the carrying out of these tests and this, to a degree, operates to render the present work inconclusive. The information covering the tests which have been made on new gears is definite and final. To a limited degree, tests were made on gears which had seen considerable service but the service tests themselves and the train operation tests were not made for the reasons given. It is much to be hoped that arrangements will be made to complete the full series outlined by the Section and thereby render available accurate information concerning the action of gears in train operation and the ability of each type of gear to stand up in service. With this added information, mechanical officers and purchasing agents would be able to equate value and cost and to understandingly purchase a definite amount of protection for a definite amount of money. If the present report does no more, it gives reliable and entirely comparable and unbiased values for new commercial gears of the various types. The values given should supplant the widely variant figures frequently given out in the past as a result of inaccurate, unscientific or incomparable tests. Attention should be called to the fact that this report must be used as a whole in order to obtain accurate and definite information concerning the draft gears. The picking out and exploit- ing of an idea shown here or there throughout the test and which favors one or the other of the draft gears tested, should be heartily discouraged and those who use the report should guard them- selves against errors of this kind. The pros and cons of all gears must be thoroughly balanced by those who are looking for the truth. In the chapter entitled "Grading of Average Commercial Gears" will be found the only place where personal opinion has in any manner entered into the report. The assignment of the number of points of excellence to the various functions of the gears is on the basis of the ideal gear and engineers who study the work may not entirely agree with this assignment. Attention is also called to the fact that on plate 69 where these points of excellence are used to rate the various gears, a column covering wearing qualities has not been included. Engineers will, of necessity, record their opinions and observations as to wearing qualities and in so doing may materially change the grading of the gears as shown on this table. In making these tests the path was entirely unbroken, the trail was unblazed. It was necessary to avoid many previous methods of testing that are erroneous and misleading. It was also necessary to forget at the outset the values of the several gears as generally reported and accepted. It was necessary to lay aside all prejudices and personal preferences. With one or two exceptions the tests were welcomed by the draft gear manufacturers, and their full co-operation was freely given. The importance of the type and design of the draft gear attachments is often not fully appreciated. The report covering the tests of attachments and of reinforced and unreinforced wooden car construction gives, probably for the first time, reliable figures for the comparison of these features of construction, and also gives some slight hint of the wealth of information on general car construction that can be developed from actual impact tests, if carefully made and reported. Acknowledgment is made of the services and hearty co-operation of Messrs. B. W. Kadel, E. M. Richards and L. H. Schlatter in the active conduct of the test in the field as well as the working up of the data contained herein. C. B. YOUNG, Manager of the Inspection and Test Section of the Railroad Administration during Federal Control. Chicago, 111., January 20, 1921. DRAFT GEAR TESTS OF THE U. S. RAILROAD ADMINISTRATION, INSPECTION AND TEST SECTION The draft gear tests of the United States Railroad Administration were origi- nally undertaken at the request of the Com- mittee on Standards for Locomotives and Cars and the Central Advisory Purchasing Committee for the purpose of determining the relative merits of the several com- mercial gears in order that mechanical ex- cellence and costs might be evaluated. The Inspection and Test Section, as a prelim- inary to any work, carefully studied all of the common methods of testing draft gears. Letters on the general subject were also addressed by the section to all of the draft gear manufacturers and to a large number of prominent mechanical officers of the roads, the replies to which showed a wide difference of opinion, not only as to the proper method of testing draft gears, but as to what performance should be ex- pected from a gear. A comparison of the many test reports submitted, showed an entire inconsistency in results, supposedly obtained under sim- ilar conditions. It became evident that a test of all gears under exactly the same conditions, removed from any proprietary influence, was essential, and also that the tests should be conducted in such a man- ner as not only to determine the compara- tive value of the several gears, but to ob- tain all the exact information possible with respect to draft gear action, and to ex- tend the study as far as possible toward the ultimate determination of the ideal draft gear. With such a program in view, the co-operation of the A. R. A. Committee on Draft Gears was felt to be desirable, and upon invitation from this section, this committee has taken an active part in the test work and in analyzing and compiling the results. The present report covers in a rather ex- tensive manner the action and comparative merits of the various gears when con- sidered from the viewpoint of impact and buffing. The opportunity for the investiga- tion of draft gears in train starting and sim- ilar operations has not developed as was hoped for, so that it is impossible at this time to present definite information in this latter respect. It is desired accordingly, that this report, which compares the sev- eral commercial gears and deals extensively with the question of cushioning and absorb- tion, shall be considered only as a part of an extended investigation into the action of draft gears, not only in buffing and im- pact, but also in train starting and hand- ling. The full investigation of draft gears should include not only,the laboratory and impact tests of the present report, but also a wide range of train operation tests and service tests, from the results of which should ultimately be determined: 1. The minimum amount of movement necessary between cars for starting trains, and whether this movement may be free slack, as between coupler knuckles, or whether it should be resisted movement. 2. Whether the beginning of draft gear compression should be an easy movement or a stiff movement, and whether there should be an initial compression to prevent movement from slight shocks. 3. The effects of recoil and what amount of release force is desirable. — 1 — 2 Draft Gear Tests of the U. S. Railroad Administration 4. The desired capacity, travel, and ulti- mate resistance of the gear, as well as the shape of the curve representing draft gear resistance for both buffing and train start- ing. 5. The coupler horn clearance and coup- ler shank clearance. 6. The life, together with the rate of wear and loss in gear capacity attending it, that should be expected from an accept- able draft gear, as well as the setting of a measure, either in time, mileage, or loss of capacity, when a draft gear should be re- moved from the car and be repaired or scrapped. DRAFT GEAR TESTING The following discussion on the general subject of draft gear testing is given for the benefit of any who may be called upon to do similar work in the future. It is important to have a full knowledge of the condition of each test gear before putting it into a test. Check measure- ments should be made, such as spring heights, barrel or housing dimensions, in- itial spring compression, initial friction compression, absolute free height, absolute friction height, and solid height, keeping a record of possible travel at any of the previously mentioned gear heights. By having such a record it will later be pos- sible to check up the gear conditions and to know whether any loss in travel is due to set of springs, wear of friction mem- bers or deformation of parts of the gear. Depreciation in any of these respects should be reported in equivalent loss in coupler or gear travel. It is important to protect the friction surfaces of test gears from any grease, rust or moisture. Even the handling of the friction faces with bare hands may leave enough grease or moisture on them to lower the gear capacity. After taking a new gear apart it should be reassembled with the parts always in their original re- lationship, and the gear should then be operated not less than ten times before mak- ing a regular test. Any rust on the fric- tion surfaces should be removed by sand papering, and the gear should then be oper- ated not less than twenty times if compara- ble and consistent results are to be ob- tained. This does not mean that the fric- tion faces of draft gears do not have de- posits of rust and other foreign material on them in service, but is given as a rule for conducting comparative tests of new gears. In testing draft gears, the gear should not be loaded beyond the solid point. Few gears will stand much service beyond their normal capacities, especially under the drop machine. The determination of the solid point, however, is often quite diffi- cult. Sometimes the spring coils, or other internal gear parts, will go solid be- fore the gear is fully closed. The result is that a greater load or drop is required to fully close the external portions of the gear than would be re- quired if normal action obtained through- out. The static test is best suited to accur- ately fix the limit of normal gear closure. In tests of other characters, such as the drop test, the gear should be closed only to the travel determined from the static cards as the limit of normal gear action. All gears, irrespective of construction, should be set up and restrained in a suit- able testing frame, corresponding in dimen- sions to the draft gear pocket in the car. The frame should be so designed that the influence of its yield will be minimized, The gear should rest in the frame upon pieces of metal corresponding to the stop faces of the gear draft lugs or other stop member. A striking plate of the same size as the coupler butt should be placed on top of the gear for receiving the blow. This will develop whether or not the gear con- struction is substantial enough to receive the coupler butt forces in service. Where followers are regularly used with a gear, they should, for comparative purposes, be set up with the gear in the testing frame. In all respects service conditions should be simulated in the testing frame, as in no — 3 — 4 Draft Gear Tests of the U. S. Railroad Administration other manner will the weak or strong points of a gear be shown. It is more convenient to test gears such as the Miner, Westing- house and similar types without a frame, but a frame is necessary for some other gears, such as the Cardwell, and in any impact testing the yield of the frame, no matter how carefully constructed, may slightly increase the results. It is there- fore only fair that all gears should be tested under similar conditions. On the subject of heating but little needs to be said. It is not often that a gear will be operated fast enough to heat it suffi- ciently to affect the results unless a wear test or endurance test is being made. In such a test the gear should not be allowed to become more than just warm to the hand. It is a noticeable fact, however, that if a friction gear is brought for testing from a cold place into a warm room, the capacity will be low; and if brought from a warm room to a colder outside atmosphere, the capacity will be higher. This is due to the deposit of moisture on the colder metal, or the abstraction of moisture from the friction surfaces of the warmer metal, as the case may be. In general the hu- midity of the air is a decided factor in testing, and an instance is known of a de- preciation of 20 per cent in a gear which could be explained in no other manner. Another point of interest is that when a gear is to be given a static test without a frame, and the free height of the gear is greater as set up than the pocket length in the car, the gear should first be compressed to slightly below the pocket dimension and then released to the exact pocket length. The compression test should then start from this released point. In impact testing, where the load passing through the gear to the supporting device is measured or compared, the gear should never be tested beyond the closing point. This rule applies particularly to rivet shearing tests and oar-impact tests. It should be remembered that after a gear goes solid its normal functioning ceases, and further testing is only of the gear housings or barrel. Hence in over-solid testing the greater deformation of a weaker gear barrel offers additional protection to the rivets for the time being, and also offers more yield in the car tests. Any consider- able repetition of such over-solid blows would, however, shortly destroy the gear. On the other hand, a sturdy gear will usu- ally shear the rivets at the first over-solid blow and will similarly produce a sudden change in car velocity, but the sturdy gear will not be so quickly destroyed. In prac- tice, no one would knowingly use a weak draft gear in order to protect draft lug rivets, but draft gear tests are frequently made with this object in view. A weak gear barrel will show up well enough for the few over-solid blows given it in a laboratory, but will shortly be depreciated or destroyed from the repetition of such blows as occurs in service. In fact, if a gear of sturdy design should shear the % in. rivets at say a total fall of 16 in., it would be entirely practical to increase this figure several inches by simply reducing the thickness of the barrel or other part receiving the solid blow. For a full knowl- edge of the functioning of a gear it is neces- sary to know only its capacity up to the point of closure and the character of its action within that capacity. Any yield or cushioning beyond the solid point is due to deformation or spring of the heads or barrel, and is obtained only at the ex- pense of strength and life of the gear. The suggestion is frequently made that all gears be tested to determine the point where a force of say 500,000 lb. is set up in the sills. On the face this would appear Draft Gear Tests of the U. 5. Railroad Administration to be entirely reasonable and a proper test for the grading of gears. But for the same reasons as before, a premium would be placed upon a weak gear construction. Furthermore, it is a fundamental principle of mechanics that there can be no force set up in any structure greater than the re- sistance offered by the structure. It there- fore follows that if a gear were constructed with an ultimate strength value of 400,000 lb. it would be physically impossible to apply 500,000 lb. through it to the car. Hence, the only over-solid draft gear tests that should be made are those that will discover the weakness of a gear rather than credit it with false merit. The destruction and endurance tests are the only over-solid draft gear tests known that will correctly rate the gears in this respect. Another practice from which wrong con- clusions are often drawn is that of testing gears against sills of different sizes and conditions. It is not fair to set up one gear on heavy channels and another on light channels, as again, the force developed will depend upon the yield and the resist- ance offered by the channels. Thus if a test were made upon 20-lb. channels it would be unreasonable to expect as high a force as upon 30 lb. or 40 lb. channels, for not only is there a greater yield of the channel, but the elastic limit of the material in the lighter channels might be reached and passed, which would preclude the possibil- ity of reaching as high a force as might be shown in the heavier channels. In other words, it is impossible to put more load into the light channels than they will stand, as the force is limited by the resistance of the structure supporting the gear. THE TEST PROGRAM The following general program was de- cided upon for the present tests as offering the best means of investigating the com- parative action of the gears: 9,000 lb. Drop Tests— Solid Anvil. Closing gears by drops of 1 in. in- crements. Recoil tests. Investigation of influence of foreign ma- terial on friction surfaces. Investigation of rivet shearing tests. Destructive tests. Static Tests. Closing gears at a rate of ]/% in. per minute. Closing gears at a rate of ^4 m - per minute. Closing gears at a rate of 3 in. per minute. Car Impact Tests. Calibrated gear in one car only, solid buffer in another car. Calibrated gears in both cars. In general three each of 18 different types of draft gears are embraced in the tests. The table of Fig. I has been pre- pared to identify the gears and to give other data of prime interest in connection with them. Fifty-nine gears in all were used because of gear failures developing during the test as follows: Westinghouse NA-1 gears No. 4 and No. 5 failed in the slow static test. Sessions K gear No. 9 failed in the slow static test. Bradford gears No. 43 and No. 44 failed in the drop test. MAHE AA/O TYPE OF GEAR < *• IS his (7) ©. @ G> e © / WESTWGHOUSE D-3 *f *tf zoo*" 4- 684** 2 3 4 WEST/AftHOUSE A/A-/ 3" 2*r 366* 2 676 *** 5 6 7 a 9 SESS/OA/S *£ *°f 202* 4 766** /o // /2 /3 SESSIONS JUMBO 3" *+f 433** 666* /4 IS /6 CARDWELL G-2S-A *f wf 440** 300* /7 /a /9 20 CARDWELL S-/6-A *4" 2«f 440** O 660* 1 2/ 22 M/A/ER A-/3-5 H" «*" 346** 2 334* 23 24. 25 M/A/ER A-2-5 **' *of 207** 4 693 26 27 28 MAT/ONAL H-/ */ uf 426** 656 ** 29 30 3/ A/AT/OA/AL Af-/ H* 2*f 372** 744* 32 33 34 NAT/OA/AL M-4- */ 24$ 322** 644** 35 36 31 MURRAY H-2S **" *f 376** 7S2« 36 39 40 GOULD /7S H' 22? 337** 2 6/6 ** 4/ 42 43 BRADFORD *£ ?4f 336 ** O 772 * 44 45 4S 47 46 49 WAUGH PLATE *£ *f 420 ** o 960 * 50 51 CHR/STY H' 22? 442** z I02.G ** 52 53 54 HARl/EY 2'8"x8"SPGS. 'f V I04** 6- if Followara 67 O 55 56 57 CO/L SPR/N6S Z-&8-CLASS 6 >? 7f //0* 6- if Fallows* eez* 5 hence the gear is put in the car under Yg in. initial compression, all of which is spring compression, the friction elements being loose when the gear is first applied to the car. Of the 3 in. gear travel, when new, the first 3/16 in. is spring travel, at which point the friction blocks first become tight. The remainder is fric- tion travel. The average weight of one of these gears is 433 lb. and as no extra followers are required the comparative per car weight is 866 lb. Cardwell Type G-25-A Gears No. 16, 17 and 18 This is the regular pattern Cardwell gear of the Union Draft Gear Company, but with the parts slightly modified to give seven contained friction members of cast iron. The customary transverse spring ar- rangement is used, with malleable iron spring-seat nuts threaded on the ends of the spring rod. The free length of this gear is 25-11/16 in. as against a pocket length of 24% in., so that the gear as as- sembled in the car is under an initial fric- tion compression of 1-1/16 in. This means, in other words, that the gear can wear an amount equal to 1-1/16 in. coupler travel before actual lost motion in the gear occurs. Of course, the ultimate resistance of the gear as well as its ca- pacity will have been reduced, but it is pos- sible to recover this in a large measure by adjusting the exposed spring-seat nuts. There is in addition to this an initial spring compression of % in. so that each spring *s — ' ** s ( \ \ r -\ / i / \ ^ ■>» ^ ^ Fig. 5 — Sessions Jumbo Gear a nominal travel of 2^4 in- It is used on 19,000 of the United States Railroad Administration cars. The gear is of the double end type, the two friction casings, sometimes termed "housings" or "follow- ers," being of malleable iron. There are can, in addition to the wear above noted, take a permanent set of 3/16 in. be- fore the friction elements become loose on the spring rod. The magnitude of the initial compression of this gear gives a high starting resistance and a stiff com- 12 Draft Gear Tests of the U. S. Railroad Administration pression curve at the beginning of the gear travel. The gear has no independent release springs and the friction springs have a value of approximately 29,900 lb. When a solid blow comes on this gear some addi- tional metal is presented to receive it. Card well Type G-18-A Gears No. 19, 20 and 21 This is the regular Cardwell gear of the Union Draft Gear Company, designed to fit in the standard 24% in. draft gear pocket and of 3-3/16 in. nominal travel. The remarks in general Fig. 6 — Cardwell Type G-25-A Gear The friction casings, which alone receive the solid blow, are castings with rather thin walls. There are a total of 20 parts per gear, nine of which are subject to wear. Seven of the wearing members are of cast iron and two are malleable iron, the latter being the main friction casings or followers. This gear is not self-con- tained but must be built up in the car. It is probably the most difficult of the gears to apply. All of the parts are rough with but little grinding or fitting done to them. The normal length of this gear is 24% in. and no followers are needed. The aver- age weight of one gear is 440 lb., giving a comparative per car weight of 880 lb. concerning the Cardwell Type G-25-A gear are applicable to this gear also. Each gear has a total of 20 parts, nine of which are subject to wear, seven of these being of cast iron and the other two being the main malleable iron heads or followers. The gear has a free length of 25 }4 in. as against a pocket length of 24% in. so that the gear, as assembled in the car is under an initial friction compression of % in., meaning that when wear equivalent to % in. coupler travel occurs the friction ele- ments become loose in the car. The springs are in addition under a combined initial compression of a % in., or 3/16 in. per spring. The value of the friction springs is approximately 29,900 lb. The nominal Draft Gear Tests of the U. 5. Railroad Administration 13 length of this gear is 24% in. and no fol- lowers are required. The average weight of one gear is 440 lh., giving a comparative per car weight of 880 lb. The relative performance of this gear and of the Cardwell G-25-A should be of interest inasmuch as the only difference in the two gears is in the length of the travel. All of the parts of both gears are the same except the two heads or follow- ers and these are designed in the case of the G-25-A gear to take up the first 7/16 in. of travel as compared with the G-18-A gear, giving heavier initial compression but leaving the ultimate resistance prac- advantage of having the friction elements held in positive engagement during a longer period of wear. Whether or not high initial resistance prevents wear that may otherwise occur from the multitude of slight movements of the easier mov- ing gear may also be indicated by service tests of these two gears. Miner Type A-18-S Gears No. 22, 23 and 24 This is a slightly modified arrangement of the well-known A- 18 gear of W. H. Miner and is the design as applied to ! ; % ■■■*'■■■■ ' ■ "■■'*- " -.•.■-.''••'■ _ - ;;;g Fig. 7— Miner Type A-18-S Gear tically the same for both gears. The G-25- A, therefore has a reduced travel but higher starting resistance. It may pos- sibly show a very slight loss in capacity due to this but on the other hand has the United States Railroad Administration lo- comotive tenders. The location of the fric- tion shoes has been changed as compared with the A- 18 gear. The present gear has a nominal travel of 2% in. 14 Draft Gear Tests of the U. S. Railroad Administration The barrel of the gear is of malleable iron and contains, by an interlocking ar- rangement, the two double coil friction springs and malleable iron spring plate or follower. The regular drop forged, hard- ened friction shoes, three in number, are used, with the central wedge of cast steel. The Miner rollers, three in number, and of 1 in. diameter tempered tool steel, are interposed between the central wedge and the friction shoes to allow greater friction pressures with possibly no greater tend- ency of the gear to stick. The entire fric- tion pressure is transmitted through these rollers. As applied to the car the main springs are under an initial compression of % in. and the preliminary spring of ^4 m « The function of this preliminary spring should not be confused with purely spring gear ac- tion, as the A-18-S gear starts off immedi- ately as a friction gear of high initial re- sistance. Inward movement of the fric- tion shoes is resisted first by the prelim- inary spring and subsequently by the main spring. Wear will increase the movement of the friction shoes upon the preliminary spring and decrease the movement upon the main springs. The travel of this gear should remain practically con- stant, irrespective of wear, and as wear occurs the friction shoes, which in the new gear extend }i in. outside of the friction barrel, will protrude farther because of the spreading action resulting from the pre- liminary spring. This will continue until wear equivalent to % in. coupler move- ment occurs when the friction shoes will extend 1% in. outside of the barrel and the shoes will then loosen. Up to this point however, the full travel of the gear will be realized as friction travel, although the capacity and ultimate resistance of the gear will be reduced. It should be pos- sible, however, to compensate for wear by inserting one or more ring washers be- tween the inner ends of the friction shoes and the spring cap or followers, thereby recovering the movement upon the main springs and restoring the original capacity. The gear has a main spring value of ap- proximately 42,000 lb. and in addition a preliminary spring value of approximately 5,300 lb. It is held to the correct length and as a self-contained unit by means of a single % in. retaining bolt. The gear has a total of 18 parts, four of which are sub- ject to wear, one of these being the main barrel or cylinder. Wear on this part will reduce its ability to withstand solid blows. The friction area of this gear increases as the gear is compressed. The gear has con- siderable grinding and fitting done to it during its manufacture. The normal length is 22% in. so that two followers are required per car. The average weight of one gear is 346 lb., to which must be added for comparative pur- poses the weight of the two followers, giving a comparative per car weight of 834 lb. Miner Type A-2-S Gears No. 25, 26 and 27 This is a slightly modified arrangement of the A-2 gear of W. H. Miner, the nom- inal travel being 2]/ 2 in. The gear has the regular malleable iron cylinder with three hardened, drop forged friction shoes and a single cast steel central wedge, the cus- tomary rollers of the Miner design being interposed between the central wedge and the friction shoes. One double coil fric- tion spring is used. The rollers, three in number, are of tempered tool steel 1 in. in diameter by 3 in. long. The rollers in this gear, as in the A-18-S gear, are not directly cushioned by the springs, but re- ceive the entire friction pressure. The absolute free length of this gear is 21 in., but it is held compressed to its Draft Gear Tests of the U. S. Railroad Administration 15 normal length of 20^ in. by the retain- ing bolt. The gear is thus under an in- itial friction compression of % in. Before this much wear could occur, however, or if wear equivalent to % in. of coupler movement should occur, the inner end of the central wedge would strike the spring that it is applied to the car as a single unit. This gear has a friction spring value of ap- proximately 22,800 lb. It is also fitted and bulldozed during the process of man- ufacture. The average weight of one of these gears is 207 lb. and there are re- quired two followers with each gear, weigh- Fig. 8— Miner Type A-2-S Gear cap, and the gear would then become purely a light capacity spring gear and further wear would be arrested. In this gear, as in the A-18-S, the total travel of the gear can never be reduced by wear, al- though the capacity and ultimate resistance will be decreased. The friction shoes will also extend farther out of the barrel as wear progresses. The gear has a total of 13 parts, four of which are subject to wear, one of these being the main barrel or cylinder. The friction area of this gear increases as the gear is compressed. The solid blow is taken upon the same metal that receives the friction load and wear will materially weaken the cylinder for taking care of the solid blow. The gear is self-contained so 2 ing 71 lb. each, giving a comparative per car weight of 698 lb. National Type H-l Gears No. 28, 29 and 30 This is a new gear of 2*4 in. nominal travel, manufactured by the National Mal- leable Castings Company. A central fric- tion column with four ways in it is cast integral with the one follower of the gear. In these ways are four friction segments or shoes. The other, or movable follower, is arranged to wedge these shoes inwardly into the ways of the column and as the gear is closed the longitudinal movement of the shoes is resisted by a single coil friction spring that surrounds the friction 16 Draft Gear Tests of the U. S. Railroad Administration column below the wedges. Four inde- pendent corner posts of 1% in. diameter steel are provided to receive the solid blow so that this force is received on entirely different metal. An independent release spring surrounds each of these corner posts. The gear is held to any desired length and as a self-contained unit by means of two Y^. in. rods with castle nuts. All of the principal parts of this gear, including the friction members, are made of Naco Electric steel, the corner posts being of tempered knuckle pin steel. All of the friction members are hardened. The gear has a friction spring capacity of ap- proximately 29,200 lb. and an additional release spring capacity of approximately 16,000 lb. The absolute free length of the gear is 24-25/32 in. so that it is put into the car under 5/32 in. initial com- pression, all of which is friction compres- sion. The gear can thus wear an amount equal to 5/32 in. travel or the spring take a set of 5/32 in. before the friction shoes become loose in the car. The capacity of the gear, however, will begin to depreciate as soon as any wear takes place. An interesting feature of this gear is that on release, the first action is a tendency to shift the friction shoes outward from their engagement with the center friction column, thus allowing greater pressures with possibly no greater tendency to stick. This is accomplished by having the bear- ing of the shoes upon the spring seat at a subtracting angle. Bronze pressure pads are provided for the contact spots on the spring seat and the outer head. These are not subject to wear, but to pressure only. The outstanding feature of this gear is that the friction elements are wedged inwardly, the outward reactions all being included in the box-shaped movable follower. There is no wear upon this member and wear should not noticeably affect the strength of the gear. Wear can be taken up by means of ring washers beneath the friction spring. The friction area . of this gear is con- stant, the pressure per square inch increas- ing as the gear is compressed, the entire bearing surface of the friction blocks sliding along the ways or flutes in the center column. This gear has a total of 26 pieces, 5 of which are subject to wear, one of these being the main center column. Considerable grinding, fitting and working constitute a part of the manufacture of this gear and it may be termed a finished gear. The normal length is 24% in., so that no followers are required. The average weight is 428 lb. or a comparative per car weight of 856 lb. National Type M-l Gears No. 31, 32 and 33 This gear is similar in construction to the National Type H-l, the most notice- able difference being that but two release springs are used instead of four as in the H-l gear. Otherwise the same description of parts, materials, and operation serves for both gears. The nominal gear travel is V/ 2 in. This gear has a friction spring value of 16,700 lb. and an additional release spring value of 9,100 lb. The free length is 25% in. so that it is put into the car under y 2 in. compression, the first 5/16 in. of which is spring compression, the remainder, 3/16 in., being friction compression. Thus the gear can wear an amount equal to 3/16 in. coupler travel before the friction shoes become loose in the car. There are a total of 26 pieces per gear, five of which are sub- ject to wear and one of these being the main center column. As in the H-l gear, the wearing surfaces are of hardened steel and are constant in area. Draft Gear Tests of the U. S. Railroad Administration 17 The normal length is 24% in., no fol- lowers being required. The average weight per gear is 372 lb. or a compara- tive per car weight of 744 lb. National Type M-4 Gears No. 34, 35 and 36 - This gear is of the same general con- struction as the two preceding National gears but has three flutes in the center col- gear can wear an amount equal to 9/16 in. coupler travel before the friction shoes become loose. It is held to its normal compressed length of 24% in. by means of two % m - r °ds with castle nuts. The gear has a total of 17 pieces, five of which are subject to wear, one of these being the main center column. As in the other National gears, the wearing surfaces are of hardened steel and are constant in area. Fig. 9— National Type M-l Gear umn with three friction shoes, and has no independent release springs. Otherwise the general description is the same as heretofore given for the other National gears. The nominal travel is 2] 4 in. The gear has a spring value of 25,000 lb. The absolute free length is 25-3/16 in. so that it is put into the car under 9/16 in. compression, all of which is fric- tion compression. This means that the The normal length is 24% in., no follow- ers being required. The average weight per gear is 322 lb. or a comparative per car weight of 644 lb. Murray Type H-25 Gears No. 37, 38 and 39 This gear is of the regular Murray pat- tern, without wear blocks, as manufac- tured by the Keyoke Railway Equipment 18 Draft Gear Tests of the U. S. Railroad Administration Company, but has been specially designed to give a nominal travel of 2% in. for use on 6,000 of the United States Railroad Ad- ministration cars. The followers, the side wedges and the cam blocks are of cast steel and are in general of sturdy design. the triple coil friction spring has a value of approximately 43,000 lb. These gears as included in the tests had no provision for taking up wear, but it is understood that a similar type is made with renew- able wear blocks. Fig. 10— Murray Type H-25 Gear This may be termed a double end gear, in- asmuch as there are friction elements in series at each end. The longitudinal movement of the heads or followers produces a corresponding in- ward movement of the side bars or wedges, this latter movement, through the four rollers and two cam blocks, producing an endwise compression of the friction spring. The rollers, which actually rotate during a compression of the gear, can never be loaded beyond the capacity of the spring, unless the spring should go solid before the limit of normal gear action is reached. No separate release springs are used and Each gear has a total of 13 parts, four of which are subject to wear, these being the four largest parts, viz., the cast steel end heads and the cast steel side bars. The friction area of this gear increases as the gear is compressed. The free length is 24-15/16 in. as against a pocket length of 24% in., so that the gear as assembled in the car is under an initial friction compression of 5/16 in. This means that the gear can wear an amount equal to 5/16 in. coupler travel before actual lost motion in the gear oc- curs. The ultimate resistance and the ca- pacity of the gear will, however, have been Draft Gear Tests of the U. S. Railroad Administration 19 reduced by such wear. In addition to this the spring is held under an initial com- pression of 11/16 in. The solid blow in this gear is taken by the same parts that receive the friction load and the bearing surfaces between the followers and the side wedges for the solid blows are not as ex- tensive as in some other gears. The gear is not self-contained and requires some special fitting up and manipulation to ap- ply it to the car, and some special ap- paratus is required to assemble the spring and rollers in their inter-locked positions between the side wedges. The parts of the Gould Type 175 Gears No. 40, 41 and 42 This gear of the Gould Coupler Com- pany has a cast steel barrel with a rectang- ular bellmouth for the cast steel friction wedges. These latter, two in number, are case hardened and are pressed outwardly against the friction faces of the barrel by a friction spring of leaf type, which is made up of two half-elliptic springs placed back to back between the wedges, each half being composed of eight plates, 3/16 in. by 7 in. by 8)4 in- lon g- This spring is applied under a slight initial compression but not enough to compensate for wear of Fig. 11— Gould Type 175 Gear gear as finished are rough with but little grinding or fitting. The normal length is 24% in. and no fol- lowers are required. The average weight of one gear is 376 lb., giving a compara- tive per car weight of 752 lb. any moment. The gear is supplied in ad- dition with a double coil release spring of 38,000 lb. value. The gear is applied to the car without initial compression. It has a nominal travel of 2% in. There are a total of 22 parts to each of 20 Draft Gear Tests of the U. 5. Railroad Administration. these gears, four of the parts being subject to wear, one of these being the main cast steel barrel or housing. Wear can be readily taken up by the insertion of liners back of the friction wedges. The solid blow is delivered upon the same metal of the heads and the adjacent face of the rocker. Friction is obtained by one rocker sliding upon another and also by the rockers rotating in seats in the hous- ings. The gear has a nominal travel of 2^2 in., but is put in the car under Y\ in. ... ■■ ' " ■ - " '£■■•„ C^X^^lB pgpp Fig. 12 — Bradford Type K Gear that receives the friction load, and wear also tends to weaken the gear. The fric- tion area is constant. The gear is self- contained when new, but wear will shortly loosen the parts so that it will fall apart when removed from a car. The normal length is 22% in., requir- ing a 2% in. follower with each gear. The average weight of one gear is 337 lb., to which must be added for comparative pur- poses two followers per car, weighing 71 lb. each, giving a per car weight for this gear of 816 lb. Bradford Type K Gears No. 43, 44, 45, 46 and 47 This gear is manufactured by the Brad- ford Draft Gear Company. It is of the rocker type, having malleable iron heads or spring housings at each end with two pairs of inter-engaging, rotative knuckles between the springs. The action is such that each spring is compressed between one initial spring compression. The friction elements are just tight when the gear is put into the standard pocket. There are a total of 10 pieces to each gear, six castings and four springs. It is noticeable that every piece of the gear, ex- cept possibly the springs, is subject to wear. Upon a strict analysis the rocker ends of the springs might even be in- cluded, as the rockers move across the end faces of the springs. The friction area is constant and where one rocker slides upon another there is practically line contact. The solid blow is taken by the same metal that receives the friction load. The gear is not self-contained but must be assem- bled in the car. The two friction springs are regular A. R. A. Class G springs, work- ing in series, and the spring value of the gear is accordingly 30,000 lb. The parts of the gear as furnished are rough. The normal length is 24% in. and no followers are required. The average Draft Gear Tests of the U. S. Railroad Administration 21 weight of one gear is 386 lb. or a compara- tive per car weight of 772 lb. Waugh Plate Type Gears No. 48, 49 and 50 This is the well-known plate gear of the Waugh Draft Gear Company. As included in the tests each gear was made up of four sets of plates in series, each set consisting of 15 spring steel plates *4 hi. by 6 in. by 11% in. Half oval followers of cast steel are supplied at each end, and two sep- arators and one full oval complete the gear proper. In addition, however, two guide plates or wear plates, are supplied a total of 65 parts, or 67 parts including the wear plates. In this gear it is difficult to give a rela- tive per car weight because of the differ- ence in yoke dimensions required. Each gear weighs 420 lb. without the two wear plates, which latter will weigh about 30 lb. each. Yoke spacers should then be added, so that a comparative per car weight of 960 lb. has been allowed for this gear. Christy Gears No. 51, 52 and 53 This gear is under development by the American Car Roof Company. It had not, Fig. 13 — Waugh Plate Gear for each gear, these being bolted or riveted to the draft sills to fill out the 12% in. sill spacing and to hold the parts of the gear in alignment. The nominal length is 24% in. and the nominal travel 2^4 m - The gear has a friction area of great extent and it is hardly probable that wear would ever materially reduce the travel or capacity. If the spring plates should take any permanent set, however, the travel and capacity of the gear would be decreased. Every gear has up to the time of the beginning of the tests, been developed to a commercial stage and has been included in these tests only upon the request of the mechanical department of one of the railroads. The gear, which has a nominal travel of 2 J / 2 in., follows in general the better-known Sessions prin- ciple of wedge blocks, except that the cen- ter block is made in halves with a roller between them to form a fulcrum. Wear is to be compensated for by using a roller of a larger size. 22 Draft Gear Tests of the U. S. Railroad Administration The outstanding feature, and the point wherein it differs from all other gears in the test, is that the frictional resistance of the gear is compounded. In most draft gears the friction movement is obtained, and to a greater or less degree the fric- tional resistance is controlled by the direct 2y 2 in. less length than the outer coil. The friction spring has a total value of 27,000 lb. No separate release springs are used. The friction box and spring barrel are in one piece, of cast steel, with a removable head bolted on the spring end of the barrel. All of the parts of this m a J u it X )' )/ / K"""N' '/"~~\i fr"*"~*v y^^irt — si !)' f / ( ) ( lif ! / y- — •? \\ .J) o Fig. 14 — Christy Gear compression of springs. In this gear the outer, or main friction members, are re- sisted, not by the spring directly but by other friction members, and these latter are then resisted by the spring itself, the fric- tional resistance being thus multiplied. This should result in a gear of very high resistance but may also result in uncertain and uncontrolled resistance. The frictional resistance of the gear is thus compounded by having the inward movement of the halves of the center wedge block seat upon and expand the additional pair of friction shoes which press upon the inner faces of the spring portion of the barrel. These last named friction shoes rest upon and compress the friction spring which is graduated, the inner coil being of gear are exceedingly heavy, the walls of the spring barrel, for example, being of 1 in. stock. The gear has a total of 28 parts, 8 of which are subject to wear, among these being the main cast steel bar- rel or housing. The gear is not self-con- tained but the friction members can fall out when the gear is removed from the car. The solid blow is taken upon the same metal that receives the friction load and wear will reduce the strength and value of the gear to resist solid blows. The friction area is practically constant, although some new surfaces are constantly coming into bearing and others going out of bearing as the gear is compressed. The absolute free length is 22-7/16 in. as against a pocket length of 22% in., so Draft Gear Tests of the U. S. Railroad Administration 23 that the gear in the car is under but 1/16 in. initial compression. Upon very slight wear, therefore, or set of the springs, the friction members will be loose. The aver- age weight of one of these gears is 442 lb. and having a nominal length of 22% in. there must be added to this the weight of two followers per car, giving a compar- ative weight of 1026 lb. per car. Harvey Friction Springs Gears No. 54, 55 and 56 These are the regular interwound Harvey friction springs as manufactured by the Frost Railway Supply Company. Each gear, as included in the tests, consisted of two of these springs set in twin fashion, side by side. The free height of each interwound spring group is 8 in., and so wound as to allow 2 in. of movement from this height, thus having a nominal travel in the car of 1% in. Each group has a plain centering Fig. 15 — Harvey Friction Springs coil of % in. diameter bar wound on a 2% in. diameter mandrel and of 7% in- free height. In receiving the solid blow the main, or inner, of the two specially shaped friction coils goes solid. This bar is made with flattened contact faces to re- ceive the solid blow. This type of gear will not work in the standard pocket without special housings. The average weight of a group of these springs is 52 lb. or 208 lb. per car. It is difficult to give a comparative per car weight but in order to compare the ar- rangement with the other gears of the test there has been added eight followers, each 9 in. by 12 in. by iy 2 in., weighing 45 lb. each, two yoke abutments, weighing 40 lb. each, and four rivets for the yoke abut- ments, weighing 5y 2 lb. each, giving a comparative per car weight of 670 lb. A. R. A. Class G Springs Gears No. 57, 58 and 59 Regular A. R. A. Class G draft springs drawn from ordinary railroad stock have been included in the tests. Each gear as numbered above was composed of two complete inner and outer coil springs, tested in twin fashion. The details of each spring group are as follows: Outer Coil 1-9/16 in. diameter bar. 8 in. outside diameter coil. 7% in. free height. 5^4 m - solid height. Inner Coil 1 in. diameter. 4% in. outside diameter coil. 7y 2 in. free height. 5^4 in. solid height. Each group has thus a possible deflection of 2% in. at a load of 30,360 lb. or a de- flection of 2% in. per gear at a load of 60,720 lb. The average weight of a group is 55 lb. or 110 lb. per gear. To this is added for comparative purposes the same parts as for the Harvey springs, giving a comparative per car weight of 682 lb. SELECTION AND CONDITION OF TEST GEARS At the beginning of these tests the vari- ous manufacturers were asked to furnish gears for test purposes, so that the gears as tested were in each instance procured directly from the proprietor, with full knowledge on his part that they were for test purposes. Whether or not gears of average manufacture were furnished must be decided from previous or additional ex- perience with the several gears and from a knowledge of the manufacturing practices of the concerns. Unless a definite state- ment to the contrary appears in this re- port it is to be understood that gear con- ditions and performances as developed dur- ing the tests are in accordance with what is believed to be average conditions. Immediately upon receipt of a test gear it was given a test number and then taken apart. The parts were marked, and meas- ured for comparison with the manufactur- er's drawings and for later comparative tests measurements. The gears were reas- sembled with the parts in their original positions and were given a definite amount of preliminary drop test work to condi- tion them for the regular tests. Westinghouse D-3 Gears No. 1, 2 and 3 These gears as received were in good average condition and conformed very closely to the dimensions as given on the manufacturer's drawings. The gears had not been built up of maximum dimension parts to produce unusual capacity. The customary practice of machining and grinding certain parts had been followed and the gears had been worked in the bull- dozer as is the regular practice in their manufacture. They showed also slight in- dication of drop test work but not an ex- cessive amount. The results obtained in the tests agree very well with results ob- tained in other tests of the same gear, par- ticularly in routine acceptance tests of gears for United States Railroad Adminis- tration cars. Westinghouse NA-1 Gears No. 4, 5, 6, 7 and 8 These gears do not have as much ma- chine work done on them as in the case with the Westinghouse D-3 gear, but are carefully fitted and assembled. The gears as received appeared to be in average con- dition and for the rougher character of the work, agreed very closely with the draw- ings. The gears had been bulldozed and had undoubtedly been under the drop test- ing machine. The bulldozing, it is under- stood, is a regular process in their manu- facture and the drop test work had not been extensive. The gear parts were not over size and the results of the tests in gen- eral are believed to be representative of the action of the average product. Sessions K Gears No. 9, 10, 11 and 12 These gears are furnished commercially with but little finishing, it being the man- ufacturer's practice to gage the parts and grind the friction blocks when necessary to bring them to gage or to smooth up the bearing surfaces. The gears as received represented average workmanship and conditions and showed evidence of having been under the drop machine for a few movements. The results of the tests in general are comparable with previous tests 24 Draft Gear Tests of the U. S. Railroad Administration 25 of the same gear, particularly in routine acceptance tests of gears for United States Railroad Administration cars. Sessions Jumbo Gears No. 13, 14 and 15 These gears as received represented av- erage workmanship and condition. They showed slight evidence of having been un- der the drop test machine for a few move- ments at some previous time, although the friction surfaces had a light coating of rust on them when received. The results of the tests are believed to be representative of the commercial gear. Cardwell G-25-A Gears No. 16, 17 and 18 These gears as received were in average condition as to workmanship and showed indications of having been under the drop machine. The springs furnished with the test gears were of excessive length, the av- erage free length being 10-1/16 in., where- as the drawing dimension is but 9*4 i n » With all the parts properly assembled on the spring rod, the springs from the draw- ings should be under 3/16 in. compression while with the gears as finished the springs were under % in. compression. When as- sembling the gears in the frame for testing, with a pocket of the same length as in the car, it required the extreme efforts of two men working on an eight-foot wrench to screw up the spring nuts. It is noted also that the average drop test results obtained from these gears are greater by slightly more than 4 in. than the average results obtained in routine acceptance tests of the same gears for United States Railroad Ad- ministration cars, whereas with all other gears used on United States Railroad Ad- ministration cars the average of the test gears was lower than the average of the commercial gears. The lowest capacity gear of this type in the present tests was more than 3 in. greater than the highest capacity gear of the same type found in the United States Railroad Administration ac- ceptance tests. It is therefore believed that the results obtained for these test gears are not representative of what may be expected from the regular product as furnished com- mercially. Cardwell G-18-A Gears No. 19, 20 and 21 These gears were received in average con- dition as to workmanship, and the parts conformed more closely to the drawings than in the case of gears number 16, 17 and 18, although they averaged above the drawings. The individual variations, however, would probably be accepted as within manufacturing limits. The averages are believed to more nearly represent the true value of the commercial gear than those obtained from test gears number 16, 17 and 18. These gears were submitted near the close of the test program. Miner A-18-S Gears No. 22, 23 and 24 These gears as received were in good average condition as to workmanship and material and the parts conformed closely to the dimensions as given on the draw- ings. They showed evidence of having been given some slight work, at least in the bulldozer, this being a part of the regular process of manufacture. The results ob- tained in these tests are in harmony with those of other tests and the gears as tested are believed to be representative of the commercial product. Miner A-2-S Gears No. 25, 26 and 27 The condition of these gears as received corresponds with that of the Miner A-18-S and the test gears are believed to be repre- sentative of the commercial gears of this type. 26 Draft Gear Tests of the U. S. Railroad Administration National H-l Gears No. 28, 29 and 30 These gears as received conformed closely to the drawings' dimensions, and the results obtained are comparable with results obtained in other tests of this gear. They showed evidence of having been worked under a drop machine or in a bull- dozer, the latter being a regular operation in the manufacture of the gear. The re- sults of the test are believed to be repre- sentative of the gears as furnished com- mercially. National M-l Gears No. 31, 32 and 33 These gears as received were in the same general condition as those of the Na- tional H-l type and the results, which con- form to results of other tests, are believed to be representive of the commercial prod- uct. National M-4 Gears No. 34, 35 and 36 The condition of these gears as received corresponds with that of the other Na- tional gears and is believed to be repre- sentative of the commercial product. National M-4 Gears No. 34, 35 and 36 The condition of these gears as received corresponds with that of the other National gears and is believed to be representative of the commercial product. These gears were submitted near the close of the test program. Murray H-25 Gears No. 37, 38 and 39 These gears as received were in average condition except that they had been given considerable work under the drop machine. In one case the friction surfaces were badly galled and scored. While the Murray gear is furnished commercially of rough cast- ings and while these test gears had prob- ably been given more conditioning than any other gears in the test, yet the results are not believed to have been influenced by it, especially as they are just slightly below the average of routine acceptance tests of the same type of gears for United States Railroad Administration cars. Gould 175 Gears No. 40, 41 and 42 These gears as received conformed closely to the manufacturer's drawings and appeared to be in good average condition except that a coating of grease was found in the interior of the gears, upon the top surfaces of the wrought steel follower plates that rest upon the main coil springs. The bottom ends of the friction wedges, as well as the lower ends of the leaf springs, bear upon the top surface of this plate and have a lateral motion thereupon. The main friction surfaces were free from grease. This condition was reported to the manufacturers, who disclaimed all knowl- edge of the presence of the grease, and at their direction the parts were cleaned and the gears placed in a condition satisfactory to their representative, who inspected them upon invitation. These test gears had been given some slight preliminary work but not immediately before shipment, as one of the gears had a light deposit of rust upon the friction surfaces. The results of the tests are believed to be representative of the action of the commercial product. Bradford K Gears No. 43, 44, 45, 46 and 47 The undeveloped state of this gear makes it impossible to compare the test gears Draft Gear Tests of the U. S. Railroad Administration 27 with the commercial product. The hous- ings showed porosity and contained numer- ous small checks. A. R. A. Class F springs were sent in mistake for the Class G springs called for in the drawings. The gears were accordingly set up with Class G springs drawn from regular railroad stock. Several variations from the draw- ings were found. These gears are to be furnished commercially of rough castings, without any bulldozing or other working, and the test gears as received were in this condition, never having been operated be- fore shipment. Altogether, the test results from these gears are not satisfactory. It is felt that avoidable defects in workmanship and de- sign are responsible, at least in part, for the breakage of gear parts that will be noted as the report proceeds. Christy Gears No. 51, 52 and 53 This is an undeveloped gear which has never been furnished commercially, so that comparisons are impossible. It is un- derstood that the gears are designed to be furnished regularly of rough castings. The test gears, however, had all of the friction surfaces machined and almost the entire external surface of the barrel had been shaped off to give true surfaces and correct dimensions. The springs averaged % in. less in length than called for on the draw- ings and the gears themselves averaged ap- proximately % in. less in length than the drawing dimensions, so that % in. of free slack would have been present in each car with these new gears applied. The gears also had % in. less of travel per gear than called for on the drawings. The drawing dimensions for the roller for the center wedge block are 1 in. in diameter by 6% in. long. In the three gears as received, the rollers were found to be of the follow- ing diameters: Gear No. 51 — % in. diameter. Gear No. 52 — 1| in. diameter. Gear No. 53 — 1 T V in. and 1% in. diameter (tapered). This finding at once raises the question as to whether in repairs the correct size of roller would be used and whether, in fact, it would not be frequently omitted en- tirely. The condition of the gears of this type indicated that this company was not in a position to furnish commercial gears. Harvey Friction Springs 8 in. x 8 IN. Gears No. 54, 55 and 56 The spring groups constituting these gears conformed reasonably close to the drawing dimensions except for the plain, inner coil centering springs which averaged 7Jf in. in free height instead of 7% in. as shown on the drawings. The results of the tests are believed to be representative of the commercial product. A. R. A. Class G Springs Gears No. 57, 58 and 59 The G springs used for the test were of ordinary carbon steel, oil tempered, drawn from regular railroad stock. The follow- ing tabulation will give the comparison of the test springs with the specification re- quirements of the American Railroad Asso- ciation: 28 Draft Gear Tests of the U. S. Railroad Administration Outer Coil Spring Inner Coil Spring Free Height Outside Diameter Diameter of Bar Free Height Outside Diameter Diameter of Bar 7M in. 7tt in. Ihi in. 111 in. 4% in. | §4 in. Specified Dimension 7% in. 8 in. 1& in. 7% in. 4% in. lin. 9,000 LB. DROP TESTS After measuring the test gears and reas- sembling them with their parts in their original positions, the 9,000 lb. drop tests were made. Except for a few gears that were added at a later date, the original se- ries of drop tests was made at the Mt. Clare shops of the Baltimore & Ohio Railroad. After the car-impact tests at Rochester, the same gears were submitted to a second se- ries of drop tests under the Pennsylvania Railroad machine at Altoona for check purposes, at which place the last few gears also were given their original drop tests. The drop tests were in all instances made with the gears supported upon a solid an- vil, a heavy plate casting being inserted instead of the springs regularly used be- neath the anvil of the Baltimore & Ohio machine. Before beginning the drop tests of either of the above series each gear was given a certain amount of preliminary work to insure the proper seating of the parts. The uniform practice was followed of first determining the drop test value of each gear, by dropping the weight from 1 in. free fall and then increasing the fall by 1 in. increments, until the closing point was reached. The gear was then given 10 blows from 1 in. below the solid height, which usually resulted in building up the capacity of the gear slightly. After this preliminary work the regular drop tests were made, the tup being again dropped through heights increasing by 1 in. incre- ments until the closing point was reached, as evidenced by flattening or shearing of lead records. In the case of gears such as the Harvey springs the solid point was pre- viously determined from a preliminary static test and this point worked to in the drop test. Two drop test diagrams have been re- produced for each type of gear to show the amount of gear closure at successive drops. These are shown in Figs. 18 to 35 inclusive, at the end of the chapter on static tests, along with the static diagrams for the same gears. The information for plotting the drop test diagrams was ob- tained during the first series of drop tests by causing the tup to drive a nail into the end of a wooden post, the penetration of the nail denoting gear closure for each suc- cessive drop. The diagrams have been plotted to the exact points recorded, with no averaging or smoothing up of the curves. The regularity of gear action can thus be seen and in such a test this is of as much, if not more interest than the general trend of the line. Some of the drop test figures obtained in these tests are higher than usually reported for gears of the same type. The care taken to have all surfaces in goo'd condition and the uniformity of testing conditions in- sures that the present results are compar- able with each other. In general through- out this report the drop tests are reported in terms of "total fall," this being the free fall plus the penetration or actual travel of the gear. Some confusion has existed heretofore in this respect but it is proper to express these results in total fall rather than free fall if the true drop test capaci- ties are to be compared. The recoil of the 9,000 lb. weight was also measured by means of a special slide on the side of the drop machine. The quantities as tabulated are for the total re- coil of the weight above the lowest point reached by it in closing the gear. The drop test capacity, foot pounds of work — 29 — 30 Draft Gear Tests of the U. S. Railroad Administration done, is accordingly represented by the potential energy in the weight at a height corresponding to the total fall required to close the gear. The energy given out by the gear upon release is denoted by the amount of recoil of the weight. The work absorbed is found by subtracting the en- ergy of recoil from the "work done," or the total energy required to close the gear. A discussion of the individual perform- ance of the gears in the drop test follows: Westinghouse D-3 Gears No. 1, 2 and 3 The action of these gears under the drop was entirely satisfactory. The initial flat- ness of the curves shows the result of the preliminary spring action and the curves as a whole indicate that the gear action is reasonably consistent throughout the en- tire range. The average total fall of the 9,000 lb. tup required to close a new gear of this type, when in good condition, is taken at 19.8 in., and the total recoil of the weight at 3.8 in. These figures are ar- rived at by averaging all of the drop test results for these gears, the same practice having been followed for each gear unless a statement to the contrary appears. Westinghouse NA-1 Gears No. 4, 5, 6, 7 and 8 The drop test results on these gears are not quite so regular as on the older West- inghouse D-3 gear, but while the diagrams are more irregular, the action in general is good. The results also are considerably higher, hence it cannot be expected to find as regular action as in the lighter gear. Gear No. 8 showed slightly less in capacity than any of the others of this type. No breakage or failure of any kind occurred during these drop tests. The average total fall required to close a new gear of this type, when in good condition, is taken as 26.0 in., this being the average value of the three gears taken through the test. The total recoil is taken at 3.4 in. Sessions K Gears No. 9, 10, 11 and 12 The drop test diagrams for these gears, while not so smooth, are yet good for a gear of such short travel. In gears No. 9 and No. 10 the spring barrels began to scale before the gears went solid; in the case of gear No. 9 this began at 13 in. free fall, and in the case of gear No. 10 at 12 in. free fall. Failure of the gears had therefore begun before closure and hence the tests are not satisfactory. The average total fall required to close a new gear of this type, when in good condition, is taken as 18.8 in., this being the average value of the three gears taken through the test, and the total recoil at 4.3 in. Sessions Jumbo Gears No. 13, 14 and 15 This gear showed considerably more ca- pacity and at the same time more uniform action under the drop test than the previous Sessions K gear. The spring barrel of gear No. 13 developed a crack during this test. The average total fall required to close a new gear of this type, in good condition, is taken at 28.1 in. and the total recoil at 5.2 in. Cardwell G-25-A Gears No. 16, 17 and 18 The action of these gears under the drop was good, the diagrams being especially smooth and regular. The cast iron friction blocks formed decided depressions in the malleable iron heads, however, and a crack developed at one corner of one of the fric- tion blocks, while in the final drop tests at Altoona one of the side friction members Draft Gear Tests of the U. S. Railroad Administration 31 was broken in halves. The average drop for the test gears of this type is 21.1 in., but as heretofore explained, it is believed that these test gears are not representa- tive, the average drop test results obtained in United States Railroad Administration acceptance tests being 16.6 in. The gear is therefore credited with a value midway be- ] tween these figures, or 18.9 in. total fall required to close an average new gear when in good condition. The average total re- coil to be expected is taken at 2.8 in. Card well G-18-A Gears No. 19, 20 and 21 This gear showed smooth and regular ac- tion under the drop, and the diagrams are entirely satisfactory. The springs of gear No. 20 took a slight set during the drop tests. The average total fall required to close a new gear of this type, in good con- dition, is taken at 19.6 in. and the total recoil at 1.5 in. It is interesting to note that whereas from the mechanics of the two types of Cardwell gear, the G-18-A should be of higher capacity than the G-25-A, yet the average results obtained from the test gears show 1.5 in. more fall required for the G-25-A than for the G-18-A. This shows further warrant for the action taken in al- lowing a reduced drop test value for the G-25-A gear. Miner A-18-S Gears No. 22, 23 and 24 The drop tests of these gears were satis- factory and the diagrams denote especially uniform gear action for all ranges. This is particularly noticeable because of the fact that the gear has a travel of but 2% in. The average total fall required to close 'a new gear of this type, in good condition, is taken at 19.9 in. and the total recoil at 4.6 in. Miner A-2-S Gears No. 25, 26 and 27 These gears did not show so regular under the drop as the previous Miner gears but the diagrams are good. The drop ca- pacity, however, is low, the average total fall required to close a new gear of this type, in good condition, being 13.2 in. The total recoil is taken at 3.8 in. In gear No. 25 the main spring went solid during this test. National H-l Gears No. 28, 29 and 30 This gear developed an unusually high capacity under the drop and while the dia- grams are not entirely smooth, yet, con- sidering the amount of fall and the short travel of 2y 2 in., the gear action is good. The average total fall required to close a new gear of this type, in good condition, is taken at 31.2 in., and the total recoil at 4.6 in. National M-l Gears No. 31, 32 and 33 The drop tests of these gears did not produce diagrams proportionally as smooth as those of the previous National gears, considering their lower capacity. The diagrams, however, show reasonably uniform gear action. The average total fall required to close a new gear of this type, in good condition, is taken at 19.2 in., and the total recoil at 3.4 in. National M-4 Gears No. 34, 35 and 36 The action of this gear under the drop was very similar to that of the National M-l just described. The average total fall required to close a new gear of this type, in good condition, is taken at 21.5 in., and the total recoil at 2.4 in. 32 Draft Gear Tests of the U. S. Railroad Administration Murray H-25 Gears No. 37, 38 and 39 These gears, while not of high capacity, showed the most regular action of any fric- tion gear tested. The diagrams are un- usually smooth and indicate consistent ac- tion throughout the full range of the gear. Considerable chafing and wear occurred during the closures under the drop. Upon removing one of the heads a cloud of dust could be blown from the friction sur- faces. Unquestionably, this wear would soon deteriorate the gear. The average total fall required to close a new gear of this type, in good condition, is taken at 17 in., and the recoil at 3.3 in. Gould 175 Gears No. 40, 41 and 42 These gears showed good action under the drop except for the fact that in each instance the plates of the friction spring took a slight permanent set. The gears showed high recoil and because of this feature it was difficult to keep them in posi- tion on the anvil. The average total fall required to close a new gear of this type, in good condition, is taken at 18.1 in. and the total recoil at 7.1 in. Bradford K Gears No. 43, 44, 45, 46 and 47 The drop testing of these gears was diffi- cult and unsatisfactory. The springs went solid before the heads of the gears came together and gears No. 43 and No. 44 failed by splitting the heads. The fail- ures were undoubtedly due to this spring condition, as extremely high forces are set up in this, as in most friction gears, if the springs go solid before the gear is closed. Gear No. 45 also developed a cracked head during the drop test. It is noticeable that the portion of the head immediately back of the coupler butt, in buffing, is not prop- erly supported. Another serious point is that in several instances the heads pinched and stuck in the frame on release. These gears showed low capacity and high recoil under the drop, their action being very little different from that of a spring gear. The average total fall required to close a new gear of this type, in good condition, is taken at 10.8 in. and the total recoil at 5.3 in. Waugh Plate Type Gears No 48, 49 and 50 These gears gave reasonably smooth dia- grams in the drop test but in each instance the plates took a permanent set. The drop capacity is low and the recoil high. The gear is of especially easy movement at the beginning of its travel. The average total fall required to close a new gear of this type, in good condition, is taken at 13.9 in. and the total recoil at 7.6 in. Christy Gears No. 51, 52 and 53 This gear was very erratic under the drop, and the action is not at all satis- factory. The gears as tested were shorter than the pocket dimension and this clear- ance allowed the wedge roller to get out of position upon recoil. The total fall re- quired to close the test gears ranges from 14.3 in. to 26.3 in. It is therefore difficult to set an average value, but in the absence of better uniformity the three results have been averaged and the total fall set at 19.6 in. for this gear. The total recoil is taken at 5.1 in. Harvey 8 in. x 8 in. Springs Gears No. 54, 55 and 56 Each of these gears as tested consisted of two Harvey 8 in. x 8 in. springs, set side Draft Gear Tests of the U. S. Railroad Administration 33 by side upon the anvil. The gears showed but little capacity under the drop, although the action was regular. In the case of gear No. 55 the springs took a slight permanent set. A total fall of 9.5 in. has been set as the drop test value of this gear (two com- plete springs) and the total recoil is taken at 4.2 in. A. R. A. Class G Springs Gears No. 57, 58 and 59 Each of these gears as tested consisted of two A.R.A. Class G springs, set side by side upon the anvil. The springs showed low capacity in the drop test, but the action was smooth throughout the range of the springs. A total fall of 5.8 in. has been set as the drop test value of two Class G springs, working either in twin or tandem fashion, and the total recoil is taken as 4.1 in. Summary of 9,000 Lb. Drop Tests The table, Fig. 16, has been prepared to show a summary of the drop tests, and the following paragraphs will explain the sev- eral columns of this table: Column 1 is selfrexplanatory. Column 2 gives the nominal travel as called for on the manufacturer's drawings. Column 3 identifies the test gears by number. Column 4 gives the actual travel ob- tained from the gears in the drop tests. In cases where the free length of the gear is less than the standard pocket dimension the actual travel has been given and an ex- planatory note made in Column 14. Column 5 gives the actual free fall of the 9,000 lb. weight required to just close the new test gears. These figures do not include the travel of the gear. Column 6 gives the actual total fall re- quired to just close the new test gears and is obtained by adding the quantity in Col- umn 5 to the actual travel as given in Column 4. Column 7 gives the actual recoil of the 9,000 lb. weight from the fall indicated in Column 6. The recoil is from the lowest point reached by the weight when the gear was just closed. Column 8 indicates the work done by the 9,000 lb. weight falling through the heights given in Column 6. Column 9 represents the energy ab- sorbed by the gear, based on the work done as given in Column 8, less the energy of recoil (Column 7). Columns 5 to 9 give the individual re- sults actually obtained with the test gears. Columns 10 to 13 give average or modi- fied results of a similar character, such as may be expected from gears of the same type, as they are manufactured and fur- nished commercially, with no selection for test purposes. 34 Draft Gear Tests of the U. S. Railroad Administration 1 8: ® CO si k 1 © 1 Ss 1 15 15 1 (5 5 is © P k) 55 Q § 5 15 15 1 i * 0) II © "3 °3 8 c\i ^0 "°0 '<0 5 «o (V) © = <0 5 n 5 5 55 k> 1 k 1 i k 1 0) Ml* © 1 5 5 5 15 $ R ^ i J3 1 io 8 55 5j 5k 03 »3 1 s 55 R! °3 ft! 2 1^ © 15 £ 5 3 k) ! Rl 10 § 5 1 k> °0 55 1 23 io S5 S5 § ^Q § 5 5$ 8 <0 55 r 5 1 1 18 03 ill © 23 °3 5 ^ N •4 "5 3 1 V ^6 5 *>> 03 £1 8 ^ ^ s ^ °3 © 35 8 8 '§ § <0 N § « '§ S § as "k § $ o is Si ^ S "is 3 ^ ^ N 'r fa k> k) 55 k) 55 5^ © ss v. Q * S 1 $ k 5 JB 2? Jt 5 ; ^ 5 5 k k k v. 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Railroad Administration 35 m 8 1 5 10 to 19 ?! <0 1? ft 1Q 00 ft 19 5i Q Q ^ $ 10 8 <* 5 ^0 to tVl 1 ^0 > to * 5 to k> to <0 B t\i \ * 53 = 0 to to ft to to St 3 5 tV/ to to io R 5 1? 5 00 o 00 § 2 0) s? 0) OS ?3 to 55 O 5 1 k) R § 15 [5 ft) ft to 2? tvi 5 ^ * 8 ^ N "J to f\l to to' <* to tvi «0 (0 "3 ^ •6 co * ^6 S 1 8 N oo ki 00 t\i N oo °0 CD 00 k> ^ ^ ^ ^ ^ ^ 8 to 3 to "5 to to 3 5 5 Vo 3 to to to N \ * N 5 V s io V ^ ^ K V Aj $ V ^J < °0 ^ ^ N ""0 to 0) to l R to to- $ se «B k N V S3 9 !8 V * te k SB 3 8 0) to M °0 iVi 5i tVl tvi Oj 00 00 to to R fc ^ «Vi Co to l»5 & *) 2? to § Is °0 to to to 5 2 to § ^ ? !§ ^9 N 29 ? § £ JVi to 85 1° to to I to to V I •Vl > > — I 8 N t 1 b 1 1 1 Si ' Is en < w O Ci, * -s a: e w Ph » H »0 if) £4 \9 CO iO ro vO r ro ro r- 2 S «0 CO CO l> en © fc'S o o CO CO ro m jo r ro ro r ro O m »0 U7 r; 04 ro to N V£ vO (0 5 Cm oc CVJ CO ro 1 «0 00 N C- O 03 h \n Ul h a: o y u u h o ™ * 5 2 f ? r F S as* © o c- o o in m m o m o OD N N N o vO VO VO t> o' o 8 ? < © 2 co CO CM 5 s 00 ^0 N f) O ro 3 O o CO »0 CM N O O «1 »0 o 00 t\i o ro en *0 0* u> CM to N CO CO ro vo »o 2 CO VO 00 00 •A CO ? to CO CO VO ro CO ro f VO S CO V£ ro vo o CO t o ^0 vT> h u h 0) Id T u < z F h lu UJ Q. in u z I UJ ir » vj 5 S © el to VO 10 CM CO CM «-» C CO CO ro rr. c- C£ m IM CO CO 10 N CO ro ro CO © cO «■ oo vO CO o ^* ro o «0 vo vo CO M s VO VO fo VO tf) en m ro ao III UJ u |I 5s 3 Of © *0 o 2 O O CM IU -J D UJ -J UJ -J o cr» ro CO to o VO 10 CO Q T C4 M> i Cft CM VO CO vo er> CO CM f UJ .ft W 3 V 1 £ v» 3 fc © vo CD CM cm tn <0 o \0 <0 CO ro CO <0 to CVJ CM «0 CO CO CO CO CM vO ^t »0 7 £ pi IS i to J UJ 3 fc © ^0 o r-- O N ro CM ro ro co CM c^ VD CO en en r CO *V39 J.S3JL © - CM rf> * ^ vD t> c» o ~ £J rr> t !£? VO tr 00 5} o CM CM (M en CM «M vr» CM VO CM CM < >-VE> 2r- § 1 1 1 I 5 Is 5* (0 to fV 1 Draft Gear Tests of the U. S. Railroad Administration 43 — r* ro vo vo oo CM «r> io 00 (O N (O VO m r^ N N m m w> CO N I vo «o o (O O v£> N A m (Vi ro ro (TV 00 ID N vO 00 £4 ro O vO CO ro ro ro 00 CD N f" ± ro ro 1? to o iO f; VO ro t- vo >o >o CO m 1*1 N 5 v£ ro vp N ft) vO CO 5" ro vO iO N vO rj> to ro ro fO VO VO f- ro ro O (0 N r- VO VO «0 CO vO CO co o cr» ro ro 10 ro CM 3 o — » N M O o O 2 52 VO VO r- ro N CO vo ro ro DO J CO N 00 •0 ro *0 vo 00 CO O M 00 "0 (0 00 m CO en t r4 N vo 00 v^v «0 «0 AT) N 10 * CO M 00 Orj fO Co CO 00 o 2 ro (0 CO CO vo T 00 N *0 «) c4 00 f vo ro 5 to 5 *0 N ON 03 to CO ON 00 ro 00 3 vo •0 On CO — CD co N ro 00 vo 00 o O QO s 00 en CO 00 «) CO m vo ro ro to CD N Vfl to VO t CO «0 vo cn •^ CO f* o 00 fO CO r- fO r> ro T W) r> (0 00 N r> vo N t S vo <0 co VO vo (Tk — ^ v© CTJ V£ 10 00 >- vo vTN N \o to tO ro 5 m ro (0 n ■J 0\ to t t> *0 ro co 00 r>- VO r> 00 r> N vo vo VO vo cn fO m V£ vo VO ' r>» vo >o ro CO VO »0 CO vo £ Ch * VO vo (0 Ul M 10 M ro U) CO N vO ro vo 0° vO h X * to N 00 «0 00 C5^ vo vo A m CD N to 10 (0 r» CO ro 5 00 rvj CO vo M CO CO 1 O vo ro CO Cm vo CO vO est vo \D N (M CO f* CO + en o VO ro t- f- co m to CO N O n B3 ro vo ro ro 00 o 1- T CM ro * * If t— * co CTv « 55 &i 55 sr 5 « K *o s? vo 1 It 1 I! Q i In fc; I V s o u I J3 I •5 r-H 44 Draft Gear Tests of the U. S. Railroad Administration n // 0-1 IC 401 psz / OJ . WJJ /a *CUJ_ ■ii v| -J i^- ■k." k M 1 5Q 1 1 i ( L U IS J; CI 10 <+• & 11 H S" 1 ^ o II s 1 ■c 0> 0^ c- g -"*- k ft *= * 1|| £ 3t i 1 o o o o 8 «0 - 4) H L w en O U) o o h o 4) fc S9CfOU/~JD3f> 9Aoqo w6iqm Jo wB&h sq-j JO SpUDSaOLI±-9DJOj & 10 u -£: u c: 10 o b CD O • a •>S9/ *- § i // ht/e. (OJ. ..< OS? icy «*/ 13 ADJJ_ 1 I j "N 10 -J 4: i i i So H Q s 3 t >\ i i 1 b 10 Q u 10 k R ! I 5 "0 "v. 4 1 L 1 •0 I* o 1 O Q 1 1 i I £ I i 1 1 i II 11 1 ll 1 g^qou/-M)de 3AoqD j\q6t9M Jo w6i3hl £<77 ^o epoD£noqj_-9DJO-/ Draft Gear Tests of the U. S. Railroad Administration 45 * ,92 ] 1/°J a*j. / - c /9AOUL 1 1 3 3 4: \ <\l \ \ ^ - to I i i 1 I 1 1 1 1 1 1 5 I 1 1 S9L/DU/ -JD3Q !§ § /j sqj jo ^spuosnoL/j_ — ajjoj 8 8 sq S „ ^ 99L/OU/-^/Ddg SAOqO Ji/6/dM JO Draft Gear Tests of the V. S. Railroad Administration 47 V J //qj s&J-/ &7 1 r g 4 1 1 1 1 ") \ CO X 8 < 131 1 5 \ 8 5 \\ £ ^ is I \ =//ey-/atQL—r9Z ! ! I I si a S3Cpt//- S3C/3U/ — -josq 3/ioqo ji/Bism jo jt/Bisy «E -JOQQ dAOCfD if) Q> jo jyS/a/s 5V7 jo spaosnoi/j- QOJOJ 48 Draft Gear Tests of the U. S. Railroad Administration i | I.LI 1 //ey /040J. " 1 1 I 0/ lioj »s^y-"' I3AOJZ \ 1 1 1 1 A i 1 1 |£\ 1 1 ! ^ M £Ji$ \ ID I 11 V 1 \ 1 s \ j Q \ » P Fl* \ Q> £ £ \ § II 1 IT) ! 1 \ — "1 1 l\ \ j fe. I y 10 -file- rs » 8 -4 1 ! 1- I 12 5^ 1/5 u S9Q0U/.JD9Q 9/icqDju6idM Jo MbidU sqi Jo spuosnoLii-dDJoj 1 j! O! -1 — j V i IS 1 1 1 1 1 1 1 ft 1 If 1 n 8 ti 1 1 55- I I St: US I 1 •> s. CDqoui-jD?9 dA0qDjCf6i^M Jo M6/9U I ID 8 sqiJo QpuDsnom 8 3DJ0J Draft Gear Tests of the U. S, Railroad Administration 49 s^s 1 * " //°j //<=> j a < >-L/ "/a i r i i \ i i i i i % » 3 3 i: ft \ 1 1 1 J \ \ t 1 1 1 1 \i t I I 1 1 f 1 1 1 J « i i 1 i sai/ou/ — ^/DBQ \ > ! 1 i i i "j S> (n -J 3 \ 1 1 f 1 I \ 1 1 1 1 •vi \ 1 1 1 1 1 \ \ 1 1 I 1 I 5 I 1 \ i i i * ^ ^ r — i 1 \ 1 1 1 5 xl 3 I i! |l §1 1 1 1 — 1 \ 1 \ 1 \ iVi ^k -1- 1 ^\ l\ 1 -* CO I I I t § spunoc/ Jjo spuosnoQj_ dDuyJ O (Q ^ lO O SdL/ou/ — _£>«?,£? dAoqo jo/Sta/A J-° -/4^>// spunoj ^j.o spuosnoL/j_ — qdjoj 50 Draft Gear Tests of the U. S. Railroad Administration 2S t ') / roj /O+0£ „ —a //< 7j a *-y % is si 1*- Co 1 l k .' k vN ^ n 1 ^ 1 I 0). cp ") 1 -* CO CO 1 1 CO Sj t i 1 to sj i; 8. ! I t i S CD o a., a 1 ^1 'Vj seyou/ — *joag ^dAoqo 4Q6/a/^ j.o -£t/6/dW "3 <\j spunod j.o spuosnoQj_ — bojoj C> d/\oqo jyS/SM jo jyBay s*?7 jo s-puosnoyj — oojoj X s-di/ou/^JDGQ 9Aoqo jc/6/dM jo jyfidH sgj jo spuo&noc/j—BOJQ-/ 52 Draft Gear Tests of the U. S. Railroad Administration O U) Q> or) M N % s<77 ^ oo jo spuosnom — dojq-/ %9L/DU/—zJDd£) dAoqo ji/fidM JO M&&U sq~j jo spuosnoc/j_ — eojcy Draft Gear Tests of the U. S. Railroad Administration 53 sdi/Du/—joaQ OAoqo ji/S/s>m jo jc/6/dp <0 > § sq-j jo &puo&noL/j_ — sdjoj S9you/-^/Odg 3/\oqo jc/S/swi jo Ji/£tep/ s-c?7 jo spuosnoi/j — eojgy 54 Draft Gear Tests of the U. 5. Railroad Administration e- • 1 1 1 p> « i Sdl/OU/ *JD9Q 9AOQD J.t/£/3M ^/<> ^.i/S/a// % % T &47 J-O spuosnoyji — ao^oj >Si V \ III,, //*. • * *s^/ ''/ 1 1 V i i h * f ! \ X ii 1 t: H ! 1 i \ \ \ > i «j » s \ V * o 99tpv/—uo*s 9Aoqo +t/£)*M J^o ^t/S/e/y 5 0) 1 b t 1 * <0 * 1 i i X 1 II -1 i ^1 u *< I "5 II ^ -> Q>| 1 1 *\ 1 i > 1 1 I 1 V '&97 J-° &puo¬f_L — sojqy Draft Gear Tests of the U. S. Railroad Administration 55 / 1 1 ., >2- t/tu aaLb IS AOJJ_- S -J 1 £ 1 § A I 8- b 8 1 ■1J • 10 Q -1 1 kr 5 l !- Hi M. i - r \ \ f 1 > 10 O O o 8 3 -1 % s \ -\ i b M a y -k *0 2 i CI o o !Q- ■^. II 1 s +-: Ik O o ^* S \ si i » IT a I ! i i • i s \ 8 1? IS ,** B = 33.A /• J ' / 9/11*4 J» S ^ Q 1 1 J -J \ ss 1 •Q -k k .■Kr.CVN I r^ s K $ b •M !( 4 9* 1) 1 3: II 1 1 I t & fc ^ 1 \ 1 1 o o 6 . — — 1 10 -Q 1 1 1 1 1 1 I 1 3 C a Q I ^1 C o o KD ■ — ii ■"& I i ■ M- i r o\ c\ 1 ^i i i i i i \ i \ i s \ i \i ■&UOUI^i&>e3A0qDJM6!3M Jo m6/9U SP1 JO SPUOSnOlU. - 9DJ0J 56 Draft Gear Tests of the U. S. Railroad Administration Sd(/OU/—JDdQ dAOqD +yS/9M JO -/-L/S&H SQ7 J^° spuosnoL/_L — sojoj <9W \ i 1/1, lt>4°L ■". ll»j +U, ,..!» 1 *APJ£ 5J > Co 1 *. 1 I S <6 1 | 1 1 1 I f Si. 1 \ \ 1 i 1 \ 1 \ i> a J SdQOU/—UDdS AlOqO ./.L/6/dM JO 4Q&dH sqj jo spuosnoyj — eojqj Draft Gear Tests of the U. S. Railroad Administration 57 7 '/€/ W2 >< \ \ v J * * * \ \ i i 4; 1 I i 1 1 i ! i £ !q § «o Q ssipu/—JD9g dAoqo ji/6/dM jo "0 it I w 1 fl ft. 1 8 Hi i f ^ H IS. 2) ,<5 o i i (ft t 4 I 1 1 « PQ en S i 5 07 c S 7 / c VUD£/?a 1 J/—33J *,£ SAO qo -{l/£/6>M JLO 4L/S/d/^ * o o -1 -* l i II 1 1 3 Nl 4: r i v-- > \ 0. c \1 oil 4 °5 <^J SpU/lOJ J.O SpUDS/?Ol/_L — dOJOj % ft a <* ^ ^ '/SA ^ |//«y /' 7/R. J S3 -y> % r J to I 't i S9 i 1 1 *l IQ Q o o 05 *> C\ 3 3 •$ 1" CO to to- "*- "V . I 4, -<8 > 8 J s i spun o ' II 1 | 1 1 1 1 1 r Q 5 j « © $9tJOU/—*JDd9 dAOgD -£L/6/dM *J0 4.t/£t9H sq~j j.o $puDsnoyj_ — aojoj l/DJ ID+OJ_ , i 1 " 1 iirj ™-y ~ "/* 55 1 \\ i V I ?i ^ ^j \ i 5 c * 8 i ! ii ! i i 1 1 1 3 i 2 , 5 ( 9 o set/ou/ — tD*9 dAoqo -f.q£i3M j.o ^.qS/Gf/ &<77^° spupsnotj / — ao^/oj 60 Draft Gear Tests of the U. S. Railroad Administration 1 I 3 'I "//tywx. ' I 1 -* • l/OJ 99^, ' ' /aAD^i L f f8 t t i t 1 1 1 1 -18 . J! i 1 1 i 51 <3 S9t/ot//—UDd$ 9Aogo 4L/6i9M ^o -wB/dH spunotf ^o spuosnoQ_L — aouqj \ CD 1 1 * * i 4: 1 i y -„99L- i ldAO-J£ L N \ j \ l| § sl > J; ^~ "~" 2g s^ 5/S" ■\ 1 s> X c> to 1 ft 8 u 1 \ 1 £ t- \l t -I I * | £ C £ O O O Q P S> Q S> 5> to > «») (y, x - spostOc/ ^o spuosnoQ_L — aojcy Draft Gear Tests of the U. 5. Railroad Administration 61 4 8 & 3 4: 41 // tjfi >M~Ju ?- .. i € \[V- \ Co II I \ \ a > \ to;8 » -V. * CO \ i a I; 3 5 i w -> c b "j 3 1 Co Is ft 1 I 1 1- (o "J: i .1 I 1 CO # 1 \ i r u if 1 II ! t \ CO * s 1 1 t a <0 o fc & £ C/J b O A en SBLfOu/ — -/os,9 dAoqo 4L/6/9M */o -Mf£f s H spunorf jlo spuDsnoyj_ — douoj CJ "0 ! , 1 8 to (0 t^ 1 vj CO (t*>. • /o +°r ;0Z.P 1 T" to % ^ ^ //' —4*- a V Y J. 9AOJI •Si | \ \ a ■ -k8- i - \ t §1 3$ CO , 1 1 i 1 5 & £ > <^ \l 1 1 3 ■vl i I i * 1- V-SJ # 'All % X, <- \\ 1 -<8<0- - to K 4) * 1 ! 3 SdL/DU/ -^3,9 dAOQD J.tj6/dM J^O 4qB/9H Spi/nOtf JLO SpUDSnOQJ^ 99JOJ 9,000 LB. DROP TESTS Friction Surfaces Coated with Foreign Material It has been repeatedly noticed when taking down gears in car repair yards that the friction surfaces, while usually worn to a good bearing contact, are not in the same clean and perfect condition as that of pro- tected test gears. On the contrary, there is frequently found an actual coating or glaz- ing of hard, black material that can some- times be scraped off with a knife. This is probably an accumulation of particles of metal, coal dust and rust. In order to obtain some knowledge of the effect of foreign material upon the friction surfaces, one of each type of gear was taken apart, after completing the orig- inal drop and static tests, and the friction surfaces were dampened and sprinkled with a mixture of pulverized coal and iron rust. The gears were then reassembled with the parts in their original positions and the dampness allowed to dry out. Each gear was then put under the 9,000 lb. drop and the closing point determined in as few blows as possible, and the gear then given 12 blows at or just below the closing point. The gear was then taken apart and the free material wiped off with clean waste. In almost every instance the friction faces were now found to be covered with a hard, glazed coating similar to that found in service. This was removed with clean, sharp sandpaper and the surfaces again wiped off with clean waste. This in every instance left the friction surfaces in as per- fect looking condition as could be desired. The action of the gears immediately after this is therefore especially interesting, as in almost every case the careful cleaning of the surfaces did not increase the capacity, and quite a number of blows were required to restore the gears to their original capa- cities. In several instances it was impos- sible to entirely restore the gears. It will be seen from a study of the results of these tests that any gear might by this method be made to show an extremely low capa- city, even though all parts of the gear were of full size and to gage and the friction surfaces apparently in perfect condition. At the same time, an inferior gear could be in apparently no better or more favored condition and yet show decidedly higher results. The table, Fig. 36, has been prepared to show the results of this test, and the fol- lowing paragraphs will more completely explain the values given in the several columns. Column 1 is self-explanatory. Column 2 identifies the single gear of each type used for this test. Column 3 gives for ready comparison the original total fall required to close this same gear. Column 4 gives the total fall required to close the gears when first operated with the mixture upon the friction surfaces. Column 5 gives the total fall required to close the gears with coated friction sur- faces, but after receiving 12 blows. Column 6 gives the total fall required to close the gears immediately after sand- papering and thoroughly cleaning the fric- tion surfaces. Column 7 gives the number of blows that had to be given each gear to restore it to its original capacity as given in Column 3. In this work of restoration each gear was operated until the original capacity 62 — Draft Gear Tests of the U. S. Railroad Administration 63 A/A/CE AA/D TYPE of GEAR TOTAL FALL OF 3000 LBS WEIGHT TO CL05E AimBER OF BLOWS REQUIRE TO RESTORE GEARTO 0RIG- lA/AL CAPACITY AFTER CLEAN- ING SURFACES REMARKS /N QfflGML cm/r/w W/TH COATED SURFACES FIRST CLOSURE AFTER CLEAN- ING SURFACES F/R5F CL05//RE AFTER TWELt/E BLOWS (/) » W (4> <® ( CO @ ® M/A/ER A-/8-A /O /9.9" 16.4' 17.5" /(? M/A/ER A -59 z 27.0" 18.0" 20S" 32 SESS/ONS R 2 13.3" 8.6" 3.0" /4 SE3S/OA/S JUMBO 2 28.1" 15.0" /6.S" 2/ A/A T/OA/AL H-l /O 3/. 2" /9.4" 26.9" 32 Fig. 37 — Drop Tests of Friction Gears Which Were Taken Out of Service, Norfolk & Western Railway N. & W. 100-ton coal cars. The gears were carefully removed from the cars so as not to disturb the deposit and glazing on the friction surfaces and were put in tight, in- dividual boxes and carried immediately to the drop test machine. The actual fall re- quired to close the gears in their service condition was determined in as few blows Column 1 — In this column the gear types are identified, and in explanation the Miner A-18-A gear is the same as the Miner A-18-S of the U.S.R.A. tests, except that the A-18-A has 3 in. travel and the A-18-S has 2y 2 in. travel. The Miner A-59 gear is an especially long gear, not usable in the standard pocket and hence not included in Draft Gear Tests of the U. S. Railroad Administration 65 the U.S.R.A. tests. The Sessions K, the Sessions Jumbo, and the National H-l are identical with the same types in the U.S. R.A. tests. Column 2 — This column indicates the number of gears carried through the N. & W. tests. Column 3 — This column gives for ready reference the total average drop test value of the several types, when new and in good condition, as found in the U.S.R.A. tests. The Miner A-18-A is taken the same as the A-18-S. For the Miner A-59 a value is taken from previous tests of these gears. Column 4 — This column gives the aver- age total fall, including the travel, re- quired to just close the gears when first tested after removal from service. These figures therefore represent the value of the gear as in actual service, after a period of three years' use, as heretofore explained. Column 5 — This column gives the aver- age total fall to which it was possible to build up or restore the gears. Column 6 — This column gives the aver- age number of blows necessary to restore the gears to the falls given in Column 5. In this test the Sessions gears, which have the friction elements of unhardened cast iron working against unhardened forged steel, showed the greatest percen- tage of depreciation and the least restora- tion. The National gear, which has hard- ened steel friction elements working to- gether, showed the next greatest percentage of depreciation and the greatest restoration. The Miner gears, which have hardened steel friction shoes working against a mal- leable iron barrel, showed the least per- centage of depreciation and necessarily the least percentage of restoration. It does not thus appear that the character, and partic- ularly the hardness of the friction surfaces, influenced this depreciation. On the other hand, the Miner gears were under a heavy initial compression in the cars and the Sessions and National under practically none. It is therefore probable that the tightness of the friction parts may have prevented the entry of the foreign material in the case of the Miner gears. In the case of these N. & W. gears, the friction shoes in the Miner gears were in every instance tight with the gears in position in the cars, while the friction members were loose in every one of the Sessions and National gears. As no measurable wear had occurred in the National gears the manufacturers offer in explanation of this loose condition of the friction members that an inferior lot of springs had been used, with consequent set and loosening of the friction parts in the car. In the case of the Sessions gears the designs provide for loose friction blocks in the car. Further investigation along the lines of gear depreciation, due to foreign material on the friction surfaces in service, should be made. DESTRUCTIVE TESTS Immediately after the tests with coated friction surfaces, the same gears, one of each of the types included in the program, were tested to at least partial destruction under the 9,000 lb. drop, the gears being supported on a solid anvil. In each in- stance successive blows were given from heights beginning at 1 in. free fall of the weight and increasing by 1 in. increments, a record being made of the point at which each gear went solid and of the point at which destruction began, as evidenced by scaling, fracture, bending or shortening of some part of the gear. These tests are of the kind best suited to show the ability of a gear to receive over-solid blows and are designed to penalize weakness instead of putting a premium upon it, as set forth in a preceding chapter of this report. It will be noticed that some of the gears begin to show evidence of distress at a fall of just a few inches above the solid point. A discussion of the individual perform- ance of the gears in the destructive tests follows: Westinghouse D-3 Gear No. 1 This gear in the destructive test went solid at 16 in. free fall, and at 20 in. free fall a number of fine cracks were observed at the tops of the convolutions that occur near the lower end of the barrel. The gear was given seven more drops, the last one being a free fall of 27 in. The cracks in the barrel had now opened up and the bar- rel had bulged at the point of the cracks to 9% in. diameter, whereas the diameter here before the test was 9 in. The barrel had shortened % in. Neither the free height nor the friction height of the gear, however, was reduced, as neither the fric- tion spring nor the preliminary spring had taken permanent set of any consequence. The travel of the gear had increased from 2y 2 in. to 3% in., due to the shortening of the barrel. This increased travel, it should be noted, is accompanied under these ex- traordinary circumstances by what would undoubtedly prove, upon repetition, to be a disastrous deflection of the friction springs. A destructive value of 23.8 in. has been given this gear, this figure being deter- mined by the general rule outlined at the close of this chapter. Westinghouse NA-1 Gear No. 6 This gear was carried up to a final blow of 36 in. free fall, the gear going solid at 24 in. free fall. At 28 in. the barrel started to scale on the ends just opposite the slots in the sides of the ends of the friction spacers. At 34 in. the barrel showed a crack at the bottom of one of the key slots. After the test the free length of the gear, which is also the friction length, was found to have been reduced % in., being now t*$ in. less than the pocket dimension. The barrel had shortened % in., the gear travel remaining the same as originally. The slots for the spacer ends had been re- duced 1% in., making the spacers bind and causing the gear to stick at lighter blows. There was no evidence of spacer failures or of the barrel deforming beneath the spacer ends, as occurred in the static tests of gears No. 1 and No. 2 of this same type. The release spring had taken a set of % in. To this gear has been given a destructive value of 30 in. — 66 — Draft Gear Tests of the U. S. Railroad Administration 67 Sessions K Gear No. 10 This gear was subjected to a maximum blow of 33 in. free fall. During the test the gear stuck and failed to release on a number of the lighter blows. The gear went solid at 13 in. free fall and at 15 in. free fall the barrel started to scale and to bulge. After this test the barrel was found to have shortened ^J in. and the friction box opening to have elongated fa in. The outer coil spring had taken a set of T % in. and the free length of the gear had been reduced by % in., being now % in. less than the pocket length and the fric- tion length 1% in. less than the pocket length. Because of the fact that this test gear, along with others of the same type, heretofore began to scale in the regular drop tests before the closing point was reached, the destructive value has been reduced below that denoted by this test, the destructive value being placed at 1 in. over the average solid value, or at 19.8 in. Sessions Jumbo Gear No. 13 This gear was carried up to a final free fall of 30 in, going solid at 21 in. The barrel of this gear was slightly cracked through one of the rivet holes in the pre- ceding drop test and attention was there- fore particularly directed to this point dur- ing the destructive test. At 25 in. the crack started to widen. At 28 in. the friction box began scaling. At 29 in. the crack in the corner of the barrel had opened % in. and at 30 in. the weight recoiled and the gear jumped enough to allow the recurring fall of the weight to land upon the side of the gear, necessitating a discontinuance of the test. Upon measurement the gear was found to have shortened fa in. in free length and the friction box to have elon- gated fa in., the gear now being fa in. less in free length than the standard draft gear pocket. In view of the questionable crack developing in this gear prior to this test, the benefit of all doubt has been given it and its destructive value of 32.1 in. is based upon the point at which this crack first started to widen. Cardwell G-25-A Gear No. 16 This gear was given drops up to and in- cluding a free fall of 32 in., the gear going solid at 18 in. free fall. At 20 in. six cracks had developed in the heads and at 22 in. ten cracks had appeared and the heads were deforming. After the test the gear was measured and it was found that the free length had been reduced y 2 in. and the solid length % in. The free length, how- ever, was still 1 in. greater than the stan- dard pocket dimension, this gear being nominally under a heavy initial compres- sion in the car, as heretofore explained. The heads had been badly deformed and cracked, and had each shortened an aver- age amount of fa in. The spring rod had bent fa in., due to the inertia of the springs and spring washers, and had elon- gated Yg in. The outer coil springs had taken an average set of % in. The friction blocks were not injured. To this gear has been given a destructive value of 20.9 in. Cardwell G-18-A Gear No. 19 This gear was given successive drops up to and including a free fall of 32 in., the gear going solid at 17 in. free fall. At 20 in. the top head began to fail and at 23 in. the top surface was depressed. At 26 in. three cracks had developed in the heads. This gear was in somewhat better condition at the completion of this test than the Card- 68 Draft Gear Tests of the U. S. Railroad Administration well G-25-A gear. A destructive value of 22.6 in. has been given this gear. Miner A-18-S Gear No. 22 This gear was given successive drops up to and including a free fall of 30 in. The gear in this test went solid at 14 in. free fall. At 19 in. free fall the springs went solid and at 21 in. free fall the barrel began scaling. At 23 in. the barrel began to bend out of line and at 27 in. a crack appeared. After the test the free length of the gear was found to have decreased % in. and the barrel to have shortened -j 5 g in., the free length of the gear being now *4 in- less than the standard pocket dimension. There was no breakage of center wedge, friction shoes or rollers. To this gear has been given a destructive value of 26.9 in. Miner A-2-S Gear No. 25 This gear was carried up to a final blow of 36 in. free fall, the gear going solid at 10 in. free fall. At 19 in. one friction shoe flaked and showed a slight crack. At 20 in. the barrel began scaling and at 24 in. bulging of the barrel could be detected. At 29 in. one crack developed in the fric- tion end of the barrel and at 30 in. a second crack developed here. After the test the free length of the gear was found to have been reduced by l T X g in., being now ■£f in. less than the standard pocket length. The friction length was 1 in. less than the pocket length. The barrel had bulged and shortened % in. and the outer coil spring had taken a set of ^f in. The friction end of the barrel had opened slightly and the two cracks mentioned had developed in this portion of the barrel. The friction shoes were each cracked in the roller seats and were cracked and flaked at the ends. The rollers had hammered and seated into the shoes and the center wedge, but the rollers were not injured. To this gear has been given a destructive value of 20.2 in. National H-l Gear No. 28 This gear was given successive drops up to and including a free fall of 60 in. in an unsuccessful effort to fracture or deform some part essential to the operation of the gear. It went solid at a free fall of 31 in. At 48 in. two of the columns showed bend- ing and at 52 in. all four columns were bent. At 49 in. the friction spring went solid and the center post of the gear came into action. At 54 in. the friction blocks had become loose. Upon measurement after the test the center post of the gear was found to have shortened -iq in. and the friction spring had taken a set of -f^ in. The free length of the gear had been re- duced y 8 in. and the length when the fric- tion shoes tightened had also been reduced y 8 in. The gear length at this latter point, however, was still % in. in excess of the standard pocket dimension and the free length % in. in excess of it, so that this gear after the test would have been under y± in. total compression and % in. friction compression in the car. The corner posts had shortened % in. and the travel of the gear had consequently been increased by this amount. The gear was not damaged in this test except for the set of the spring and the shortened and bent corner posts, which, incidentally, are simply round steel bars of 1% in. diameter by 19% in. long and could be readily straightened. The gear after this test was entirely serviceable. In view of the fact, however, that the col- umns bent at a point 17 in. above the solid point of the gear a destructive value of 48.2 in. has been given this gear. The ability of this gear to withstand punish- ment is very remarkable. Draft Gear Tests of the U. S. Railroad Administration 69 National M-l Gear No. 31 This gear was tested up to a final free fall of 48 in., going solid at 17 in. free fall. At 27 in. one of the columns started to bend out of line and at 35 in. three columns were bent, the fourth one bending at 39 in. At 42 in. the center post came into action and at 44 in. the spring went solid and the fric- tion shoes loosened. After the test the col- umns were found to have bent 1 in. out of line and shortened j$ in. The friction spring had taken a set of % in. and the center post had shortened T 5 g in. The free length of the gear had not been re- duced, but the length at which friction starts had been reduced jq in., this length being now the same dimension (24% in.) as the standard draft gear pocket. Ex- cept for the bent corner posts, the gear was suitable for service after this test. Inas- much as the first of these started to bend at a drop of 10 in. above the solid point, this gear has been given a destructive value of 29.2 in. This gear, like the National H-l, shows exceptional ability to withstand severe punishment. National M-4 Gear No. 34 This gear was given successive blows up to and including a free fall of 48 in., the gear going solid in the test at 17 in. At 23 in. three columns were bending. After the completion of the test, all four columns were bent approximately Jf in. out of line and one of the heads had a small crack in the column guide, due to the bent col- umn. The center column had not come into bearing to assist in taking the solid blow and the spring had not gone solid, although it showed a set of % in. The absolute free height of the gear had been reduced by % in., but would still have been under compression in the car. The gear, after this test, would have been en- tirely serviceable except for the bent corner posts. In view of the fact that the corner posts began to show bending at 6 in. above the solid point, the destructive value of this gear has been set at 27.5 in. Murray H-25 Gear No. 37 This gear was given successive blows up to and including a free fall of 26 in., the gear going solid at 15 in. At 20 in. the side members began to scale and at 21 in. bulging could be detected. Also at 21 in. the spring went solid. Upon measurement it was found that the free length of the gear had been reduced % in., being now % in. less than the standard pocket length. The shouldered side members had shortened T 7 6 in. and had bent and bulged. The wedge-shaped openings in the heads had spread an average of % in. To this gear has been given a destructive value of 22 in. Gould 175 Gear No. 40 This gear in the destructive test was car- ried up to 32 in. free fall, going solid at 15 in. free fall. At 19 in. free fall the barrel began scaling in the reduced lower portion and at 20 in. bulging of the barrel could be seen. At 26 in. the mouth of the barrel cracked slightly. After this test the barrel was found to have shortened % in. and the barrel mouth to have spread T 3 g in. The free length of the gear was reduced % in. and the friction length % in., the gear travel having been reduced from 2 T 7 g - in. to 2 T % in. and the friction members having be- come loose, the free length being T % in. less than the standard draft gear pocket length and the friction length {$ in. 70 Draft Gear Tests of the U. S. Railroad Administration less. The outer coil spring had taken a set of T % in. To this gear has been given a destructive value of 22.1 in. Bradford K Gear No. 45 This gear in the destructive tests was car- ried up to a final free fall of 24 in. The gear during the drop test immediately pre- ceding it had been given free falls up to and including 10 in. and at this point in the previous test the top head had cracked and had been deformed T 3 e in. All of the springs had been solid and had taken per- manent set. As the destructive test pro- ceeded the gear showed increasing failure and deformation. At the conclusion of the test the springs had taken a set of % in. and the gear had been shortened % in. The heads were badly cracked and deformed. To this gear has been given a destructive value of 11.8 in. Waugh Plate Type Gear No. 48 This gear was given blows up to a final free fall of 32 in., the gear going solid at 10 in. free fall. Some set of the plates had taken place at 12 in. and at 14 in. the gear was loose in the standard pocket by ■$$ in. No parts were broken, but the free height of the gear was reduced % in. and a number of the plates were given a notice- able camber. The gear, however, even though loose in the pocket, was serviceable. A destructive value of 15.9 in. has been set for this gear. Christy Gear No. 51 This gear was given blows up to a final free fall of 42 in., going solid at 12 in. The barrel started scaling at 20 in. At 24 in. bulging of the barrel could be detected. After the test the barrel was found to have shortened % in., the free length of the gear having been reduced % in., being now || in. less than the pocket length and the friction length lg 3 ^ in. less than the pocket length. The barrel was bulged 1% in. at points in its sides where the metal is cut away to provide space for the spring, seven cracks having developed in the barrel at these points. The outer coil spring had taken a set of *4 in. To this gear has been given a destructive value of 27.6 in. Harvey Springs Gear No. 54 Two Harvey 8 in. x 8 in. friction spring units were set side by side, in twin fashion, and were given successive blows up to and including 40 in. free fall in an effort to break a spring. Except that at 32 in. a small corner of no consequence broke off the end of one coil, no breakage occurred. Set, however, was noticed much earlier. The friction coils when received were each 8^8 in. in height, and at the beginning of this test were 8 in. and 8^ in. free height. After the 11 in. drop the friction coils both stood at 7-Jf in. height. After the 18 in. drop they stood at 7% in. and after the test at 7% in., each having taken 1 in. set during the test and being % in. less than the pocket length. To this gear (two 8 in. x 8 in. Harvey springs) has been given a destructive value of 14.5 in. Two A. R. A. Class G Springs Gear No. 57 These springs were set up side by side, in twin fashion, upon the solid anvil of the 9,000 lb. drop machine. During the reg- ular drop tests the springs took an average set of j 3 ^ in. Upon further testing more pronounced set occurred, at 6 in. free fall, the average being T 3 g in. per spring. Thev Draft Gear Tests of the U. S. Railroad Administration 71 Ma/TE AND Tyre of Gear Test Gear No. 9000* Weight Develofe- ment OF /a/lure Avg.7utal/xll S000*WE/<5/iT Required To Close One Commercial. $$£§ OF THIS Destruct- ive Value Ass/gned To T///sType Of Gear Total Tall REq'D. TO CloseGear InTh/sTest Add/t/onal Fall Beyonc Clos/ngPo/nj Required lb Start /ailurl © ® ® 0) ® © (7) ® WESTINGHOUSE D-3 /<3 21.6 " /6.6 " /S.9 22.6 13.6 " 2/.o SESS/OA/S A IO 23./" /S./ " ZO.S " 22./ " f/.O " /7.S " CAROWELL G-25-A S tl.G " /&6 " /S.6 " ao.e " IS.S " /S.3 " MURRAY H-25 7 n.Q " /G.8 " ne " 20.8 " n.e " 20.0 " Fig. 39— Results of %-in. Rivet Shearing Tests. Draft Gears for U. S. R. A. Cars 9,000-lb. Drop tests and was the final test given the gears. The results are given in the table, Fig. 40, the several columns of which are de- scribed as follows: Column 1 is self-explanatory. Column 2 identifies by number the gears that were subjected to this test. Column 3 gives the original total fall re- quired to close each gear. During this test care was taken to see that all gears were up to this original capacity. Column 4 gives the free fall required to shear the rivets of one or both lugs. This height of fall was reached through succes- sive blows increasing by 1 in. increments. instance exceeded .15, the usual average ranging from .09 to .12. Some of these results will at first thought appear inconsistent, but a more careful study will show that the results in general are approximately what should be expected when gears of different travels and capaci- ties are tested upon undersized rivets. Thus the gears generally may be divided into two classes : those closing at four miles per hour or more in the car-impact tests and those closing at less than four 'miles per hour. Seven types as follows fall in the higher class: Draft Gear Tests of the U. S. Railroad Administration 75 AtAFE AND TYPE OF GEAR % II GO @ (?) fc> CO <® (7) WESTINGHOL/SE D-3 2 /S.fO" 77" 2.4T 13.5 " ONE WESTINGHOUSE A/A-/ 7 ze.oo" 2/" Z.66" 23.7" BOTH SESS/ONS // 20.06 ■ II" 1.45" 12.5 " ONE SESSIONS t/UMSO 14 27.06 14" 2.10" /6./ " BOTH CARDWELL G-2S-A 17 20.75" 20" 2.75" 22.8" ONE CARDWELL G-/6-A ZO Id. 29" 73" 3.29" 21.3 " ONE M7NER A-/S-S 23 /9.S2" 77" 2.47" /$«5" O/VE MINER A-2S 275 13. S3" //" 2.53" 13.5 " OA/E NATIONAL 23 32.50" 9" LOO" 10. " ONE NATIONAL M-/ 3Z 18.53" n" 2.53" 13.5 • ONE NATIONAL M-4 J& 23.46" 17" 2.30" /S.J " BOTH MURRAY H-25 . „„/,,„///* /,///„/////,//. /.€7' 2.S0' Fig. 41 — Diagrams of Rivet Shearing Action of Draft Gears 78 Draft Gear Tests of the U. S. Railroad Administration were prevented by breaking of the set-up, but this limited experience showed the fu- tility of attempting to use full-sized rivets for testing all gears. From this experience and from careful study, it is believed the present y% in. rivet shearing test is not a fair method of grading gears. Car sills are designed for a load of 500,000 lb. and it therefore should not be expected to hold the draft gear to the limits required by this light test. It is believed possible, however, to develop a rivet shear test to grade gears of all capacities, and investigations have been outlined to develop a test of this char- acter. In this work the following points will be established or disproved: 1. That rivet shearing tests should be designed to show smoothness of action and the ultimate dynamic resistance of the gears. 2. That such tests should not be carried beyond the solid point of the gear, because of the fact that all gears are not of equal rigidity when solid. 3. That the rivets should be of such area that a single blow may be given from a stated height, within the capacity of the gear, and the rivets not be sheared. 4. That the rivets should shear at a blow from not more than a stated height above the solid point; this in order to penalize over-solid weakness of construction. 5. That the tup should not be dropped through successive heights increasing by 1 in. increments because of passing the elastic shearing limit of the rivets before the gear is solid, but that the gear should be set up on lugs or the equivalent and a single blow given from a specified height for that particular gear and the rivets not be sheared. Using a new set of lugs, an- other single blow should be given from a second specified height at which the rivets should shear. 6. That the number of rivets used and the heights of drop should not be the same for all gears but should be set for each type in accordance with its capacity and travel. 7. That the rivet area and height of fall should be determined by the drop test ca- pacity and travel of the gear. 8. That the test rivets should be of high carbon steel or other material having a high elastic shearing limit; this in order to avoid the uncertainty of the exact shear- ing point. 9. That when all gears are constructed of equal travel the question of rivet shear- ing tests will be greatly simplified. CAR-IMPACT TESTS In order to obtain an exact knowledge of the action of gears in service, car-impact tests were made, using the same gears as in the foregoing laboratory tests. The re- sults are therefore of especial interest as showing not only the action of the gears themselves under service conditions, but as demonstrating also, for the first time, how laboratory tests compare with service ac- tion. The gravity testing plant of the T. H. Symington Company at Rochester, N. Y., was used for these tests. In general, the use of private laboratories of interested companies was avoided, the preference be- ing given to the testing facilities of rail- roads. This being the only plant of its kind in existence, however, and the Sym- ington Company being interested in the manufacture of draft gear attachments rather than of gears, and having no gear in the tests, the Section availed itself of the opportunity to use the Symington test- ing facilities. This plant was originally built for in- vestigating the action of full-sized cars, either loaded or empty, when equipped with different draft gears. The Symington Company, who were practically pioneers in this work, constructed the plant with the prime idea of studying the action of the cars when equipped with different gears rather than investigating the action of the gear itself. As originally constructed and used, much valuable information was ob- tainable from this equipment although, as in any other impact testing, misleading con- clusions as to the relative merits of draft gears could be unintentionally reached by subjecting gears to oversolid car veloci- ties. The extended remarks heretofore made regarding over-solid laboratory test- ing apply equally as well to this service testing. Over-solid testing should never be done except for discovering weak gear con- struction. Some of the earlier tests have been of value, however, in showing what slightly over-solid speeds are necessary to produce gear injury and failure. After the owners had made certain changes and ad- ditions desired by the Section for a more exact investigation of both gear action and car action, at speeds within the ranges of the gears, the Symington plant was taken over and operated by the United States Railroad Administration for the purpose of the car-impact tests. The Symington Test Plant In general this test plant consists of a test track with two full-sized cars which can be caused to collide at any desired velocity, accurate means being provided to record the results. The first portion of the track is inclined in' order to impart velocity to one of the cars. This section of track is 147 feet in length and is on a general grade of 12 per cent. An electric hoist is located in a small house at the top of the incline and this hoist through the medium of a puller car, is capable of draw- ing a loaded 50-ton car up the incline. At the foot of the incline is a 53 ft. section of approximately level track which terminates in a 196 ft. section of track on a 1 per cent ascending grade, this in turn termi- nating in a 287 ft. section of track on a iy 2 per cent grade. The entire test track is thus 683 feet in length, beginning on a 12 per cent descending grade and ending on a iy 2 per cent ascending grade. The track is straight throughout its length. 79 80 Draft Gear Tests of the U. S. Railroad Administration Draft Gear Tests of the U. S. Railroad Administration 81 Qhj— &bO 8$ |5 S6> #3TVto- %\ A xw/si/cu m Two composite gondola cars of 50 tons capacity are used, one of which, termed for reference car "B," is spotted at a cer- tain point at the beginning of the 1 per cent grade. The other car, termed car "A," is drawn up the incline by means of the puller car and hoist. A movable trip block is clamped on a third rail located alongside the track. The puller car has a projecting trip-lever which strikes the trip block, releasing car "A" and allowing it to roll down the incline. When fully on the level portion of the track, car "A" col- lides with the standing car "B." Either or both cars may be equipped with draft gears of any type, and both cars are free to follow such movement during and after the draft gear cycle as -may result from the use of the particular gear. A general photographic view of this test plant is shown in Fig. 42. Fig. 43 shows the general profile of the test track with the test cars in positions as at the first instant of impact. While the general condition of the track is good, any local variations in elevation would influ- ence the results of the tests unless con- sidered in the calculations.' Accordingly a minute check of the critical portion of the track was made, the levels being taken while moving the loaded cars over the track. Fig. 44 shows in magnified scale the true path of the center of gravity of one of the test cars as it moves along the portion of the track traversed by the cars during the tests. Figs. 45 and 46 show to a still greater magnification the exact paths of the centers of gravity of the two cars over the short portions of the track trav- ersed during the draft gear cycle. With the aid of these profiles, Figs. 44 to 46, it is possible to make a careful and exact study of the energy transferrence from one car to the other, and of that absorbed by the draft gears and cars. The test cars are 50-ton low side, com- posite gondolas, 46 ft. in. inside length with fish-belly center and side, sills and 82 Draft Gear Tests of the U. S. Railroad Administration with a steel frame superstructure. The cars have 214 in. floor planking and S 1 /^ in. side and end planking. Each of the cars has four diagonal floor braces of 5 in. channels at the corners, and each has been supplied in addition with four diagonal braces at the center, extending from the side sills to the center sill, these latter braces The test cars are equipped with Farlow Two-Key draft gear attachments as shown in the photographic reproduction, Fig. 48, and the test gears may thus be carefully adjusted in the draft gear pocket. In this arrangement the gear is positioned between the arms of the horizontal wrought steel yoke. In buffing, the gear seats against the / Prof//e defined ny center of growfy of a fesf car mov/na a/on6 test track. \ tior/zonfat Scotef"=8ft Verf/caf Seated W ft: /O /5 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 35 ZOO /05 //0 Cor Movement — Feet Fig. 44 — Enlarged Profile of Test Track for 90 Feet being 6 in. by 4 in. by % in. angles. The light weight of each car is 47,800 lb., and they have been loaded with pig iron to give a total gross load of 143,000 lb. per car. Wood cribbing is arranged inside of the car to hold the lading against shifting. A general view of one of these cars (car B) with its lading is shown in Fig. 47. These cars were reweighed and the lading prop- erly adjusted and distributed before be- ginning the tests. Care was taken to avoid testing after heavy rainstorms, as it was found that each car took up approximately 1,200 lb. of water during a prolonged rain. The brakes were removed from the cars to avoid any possibility of dragging shoes. rear follower, which latter bears against the rear of the yoke. The yoke in turn seats against the cast steel back-stop and bolster center casting. This casting bridges be- tween the sills and ties them together, there being a total of seventy-four % in. rivets supplied for transferring the buffing force from the backstop casting to the center sills in each of the test cars. The draft gear is held to compressed position by means of the second draft key, which in service forms also the front pulling stop for the gear. The regular practice in this form of attachment is to have this key protect the draft gear by allowing it to strike the ends of the slots in the check Draft Gear Tests of the U. S. Railroad Administration 83 plates and sills at the same time the gear goes solid. In the tests, however, the slots were lengthened at the rear to prevent this key ever going solid. A dummy coupler having a flat buffing face and of 16 sq. in. cross sectional area, was used instead of a standard coupler. The artificial looseness or slack resulting between the coupler butt and the front fol- lower was taken up by temporary wedges before each run so that all action, both on compression and release, could be re- stricted to the gears themselves and be definitely measured and recorded. f2 08 04 Defait Faff? of center of gravity of Cor A during impact fiorizontot 5co/e ■/"=/" Verticat Scafar=j£>ft i 53 ~-T/?/$ tine corresponds w/in Station 20 on D/agrdm figure 23. 234-56735/0 Cor Movement 1 — /ncfyer Fig. 45 — Enlarged Profile for 12-in. Movement of Car A // /2 276 212 2.68 5P Detaii Path of center of gravity of Cor 3 daring impact ftonzonfat Scaie-t '"=/"_ Vert/cat 3cate-f'= / t ft 264 * — This //ne corresponds with STo. 70 on Diagram F/gure 29. 260 Fig. 46- 3 4 3 6 7 8 3 Cor Movement— inches -Enlarged Profile for 12-in. Movement of Car /O // /2 The front key, which passes through the key slot of this coupler and through the front slots in the yoke, was used in these tests for supporting and aligning the parts only. The front end of the dummy coup- ler shank was guided both vertically and laterally. In all tests care was taken to see that the draft gears seated against the sec- ond key and not against the coupler key. Action of Cars During Impact In any case of car-impact, the first and prime effort is for the velocities of the two cars to equalize; that is, for car A to slow down and car B to speed up. This is caused by the effort of car A to push car B ahead, which continues as long as the velocity of car A is greater than that of 84 Draft Gear Tests of the U. S. Railroad Administration Fig. 47— General View of Car B and Its Lading Draft Gear Tests of the U. S. Railroad Administration 85 car B. This pushing or propelling effort must always result in the compression or yield of some part or parts of the car. The draft gears are supplied for the purpose of providing this yield and to reduce the amount of yield required from the car structure. But in every case of impact, plished by certain forces working through a certain space represented by the addi- tional yield of the solid parts, the force going directly through the housing to the sills. The couplers, gear housing, and sills must now continue to yield until the car velocities are finally equalized. The amount Fig. 48— Farlow Two-Key Draft Gear Attachments Used on Test Cars some part or parts of the cars, either draft gears or other more rigid car parts, will continue to compress or yield until the very instant when the velocities are equal. For light impacts, the velocities are usually equalized without compressing the draft gears to their full amount. In the case of an over-solid velocity, the draft gears will first be fully compressed, their resistance slowing down car A and speeding up car B. But in this over-solid case, when the gears are fully compressed, car A has still a greater velocity than car B and it will be apparent that car A will continue to urge car B forward. This results in an impact directly upon the gear housing. The ad- ditional work to be done must be accom- of yield and the magnitude of the forces are inversely proportional and depend en- tirely upon the sturdiness of, or the re- sistance offered by, the parts. The sturdier the parts, the more force will be required to deform them and the less will be the amount of penetration and yield and in- cidentally the lower will be the unit stress. On the other hand, the lighter the parts the greater will be the yield and the less the force, but the higher will be the unit stresses. Accordingly, although providing a temporary cushioning for the over-solid blow, the lighter parts will shortly be de- formed or broken. Any weak link, be it coupler shank, draft gear housing, draft lugs or center sills, will reduce the force 86 Draft Gear Tests of the U. S. Railroad Administration peak but only at the expense of its life. The velocity of car A is thus being gradually decreased and that of car B in- creased until the velocities are equal, at which instant all parts have reached the maximum of compression. If all of the parts were perfectly inelastic, if in other words, there should be no tendency for the gears to release themselves or for the car structures to give back the energy of their elastic yield, it is evident that there would then be no force of recoil to separate the cars, and both cars would accordingly move off together at this equal velocity, each car having one-half of the original velocity of car A, neglecting a slight loss due to internal resistances. With equal rolling and grade resistance, the cars would continue together until both finally came to rest without separation. Except for the slight loss due to rolling resistance, the work done in compressing the gears and car structure is thus always equal to one-half of the original kinetic energy in car A, and it should be especially noted that this is the same whether there be no re- coil of the gears and car parts, or full re- coil. The force exerted between the cars in compressing the gears and car structure is entirely independent of the question of ab- sorption. Up to the point of maximum compression the matter of absorption of energy has not entered into or influenced the problem. It is entirely a question of force and yield and it should be remem- bered that frictional resistance, while truly absorbing energy (foot-pounds) does not in any manner whatsoever reduce or "ab- sorb" force. The force required to close a friction draft gear, and consequently the force going through the gear to the sills, may be greater or less than a spring draft gear of equal capacity, depending solely upon its compression curve, and not in the slightest degree upon its percentage of absorption. The cushioning value of a gear therefore is not measured by absence of re- coil, or energy absorption, but solely by its action during the closing period. Whether or not a gear has extensive recoil has nothing to do with its action on com- pression, or with the force delivered by the gear to the car during its compression. In practice, the cars having reached a point in the draft gear cycle where their velocities are equal, and the compression period of the cycle completed, the re- lease of the gears begins. All gears have more or less recoil and it is this force, together with the rebound of the car struc- ture, that tends to part the cars and to cause one car to travel faster and farther than the other. It should be especially noted that the force of recoil has the same effect be- tween the cars as the force of compression; namely, to reduce the velocity of car A and to increase the velocity of car B. During the period of gear compression the force between the cars, or the force tending to accelerate car B, results from the higher velocity of car A, or its direct tendency to push car B ahead. During the period of draft gear release, the force tending to further accelerate car B or to urge it forward, results from the recoil or return of stored energy in the two draft gears and both car structures. The recoil of the gears and car parts thus giving to car B a greater velocity and to car A a lesser velocity, car B will begin to travel faster than car A, and the gears, following the resulting parting of the cars, will continue to release until final separa- tion of the cars. It is evident that the greater the force of recoil, or release, the greater the pressure between the cars dur- ing release, and consequently the higher will be the velocity attained by car B and the greater the retardation of car A. A gear with 100 per cent recoil would ac- tually bring car A to rest by the time the Draft Gear Tests of the U. S. Railroad Administration 87 cars separate, while car B would be pushed ahead at a velocity practically equal to the original impact velocity of car A. On the other hand, a gear with no recoil, or 100 per cent absorption, would, as heretofore set forth, cause both cars to move off to- gether, each at one-half the initial velocity of car A. Gear absorption is thus inversely proportional to the pressure exerted be- tween the cars during the period of release, the effect of high absorption being to hold the two cars at nearly equal velocities after impact. This means, in effect, that with high absorption of energy, car B will not be propelled at so high a velocity and con- sequently will strike the next succeeding car at a reduced velocity, while with no absorption, car B will strike the next car at almost the same velocity as the original of car A. Absorption therefore is not primarily a means of reducing the force of impact between the first two cars, or of protecting these cars, but is a means of re- ducing the moments of the successive im- pacts between successive cars in a train. The following may be acepted as general principles of draft gear action in impact: 1. That draft gears are compressed only because of differences of velocity between adjacent cars. 2. That the resistance offered by the gear during compression tends to overcome the difference of velocity of the cars and tends to bring both cars to the same velocity. 3. That gears continue to close, and at over-solid velocities the car structures con- tinued to compress, until the car velocities are equalized. 4. That this action of a gear is inde- pendent of its ability to absorb energy, or in other words, is the same whether- the re- sistance be obtained from friction or solely from spring action. 5. That the cushioning offered by the compression of a draft gear is not depend- ent upon its percentage of absorption. 6. That absorption does not in any man- ner reduce the force going through the draft gear to the car sills while the gear is being compressed, and does not lower the force exerted betwen the first two cars col- liding. That it does act to lower the ve- locity with which the second car strikes the third car and consequently reduces the force between successive cars. 7. That the amount of "work-absorbed" by a gear, or the percentage of absorption does not regulate or reduce the force of first collision, but is important as deter- mining whether shocks will run practically undiminished throughout the train or whether there will be successive reductions in their moments from car to car. 8. That the first measure of a draft gear is the amount of energy required to close the gear, this being the sole factor from which to determine for what switching speeds a gear is suitable. This is ex- pressed as "work-done" and has no rela- tion whatsoever to "work-absorbed." 9. That the next requirement is that a gear, either spring or friction, shall com- press with such a rate of' increase of re- sistance as will cause the lowest practical ultimate force and the least practical vibra- tion of the car structure. 10. That the next measure is with respect to the action of the gear on release or the amount of the recoil, whether the energy of compression is returned, to go on to the next car, or whether it is partially absorbed as by friction. This property is expressed by the term "work-absorbed." Records in Car-Impact Tests In the car-impact tests the following records were taken: Impact velocity of car A. Travel of cars along track. Draft gear travel and action. Seismograph readings. Graphs of car action. 88 Draft Gear Tests of the U. S. Railroad Administration From these prime records a complete study of the action of both the gears and cars can be made, the details of which will appear as the manner of making and in- terpreting the several records is discussed. Impact Velocity The first information needed in such tests is an accurate knowledge of the vel- ocity of car A at the very instant of im- pact. It is not enough to simply release the car at a fixed point along the incline, for the same station will not always de- velop the same velocity. Nor is it satis- factory to establish five-foot or ten-foot stations near the point of impact and cal- culate the impact velocity by means of the average velocity between these stations, as very marked changes in velocity may oc- cur over such periods. The kinetic energy of car A is determined from the impact velocity, and as it varies with the square of the velocity, and furthermore as all of the results of the tests are based upon this rec- ord, accuracy here is of utmost importance. In these tests car A was caused to draw a velocity line upon a revolving drum, so that the exact velocity at the very instant of impact is obtained within a possible er- ror of less than 1 per cent. A more de- tailed description of the recording device will be given later under the heading of "Car-Movement Curves." Travel of Cars Along Track An interesting record, easily obtainable, is the distance each of the two cars travels along the track after the impact. Care must be taken in interpreting these figures, however, as a slight change in grade wilj offset a considerable track movement of the cars. Thus, if but one of the eight wheels of a car mounts an obstacle on the track -fa in. in height, it is equivalent to six inches additional movement of the en- tire car along level track. An interesting point in connection with this record is that for equal impact velocities, the higher the recoil of the gear used, the greater the distance car B will travel. In general, the recoil of gears will be proportional to the distance between the cars after coming to rest; that is, the greater the recoil the farther apart will be the cars when they come to rest. Draft Gear Travel and Action Knowing the impact velocity, the next point of interest is the amount of and the nature of the travel or yield of the draft gears. The test cars are equipped with fric- tion plunger gages to show the amount of coupler travel. This corresponds reason- ably closely with the actual draft gear travel, but is not sufficiently accurate for analytical investigations. In order to obtain a more direct knowledge of the movement and action of the gears, car B is provided with a small revolving drum upon which is drawn a curve which shows not only the amount of draft gear movement for that car but the character of the movement; that is, whether the gear compresses and releases regularly or irregularly. A pho- tographic view of this instrument is shown in Fig. 49, a case or bracket being secured to the side sill of car B in which is a small motor-driven drum which extends trans- versely of the car. A pencil is caused to move lengthwise of the drum in harmony with the movement of the front draft gear follower. For this purpose a piano wire extends from this draft gear follower to the pencil arm, the connections being arranged in such manner that tipping of the follower block will not produce false movement of the pencil. Relative movement between the side sill and the center sill is also com- pensated for. A 40 lb. coil spring and a 40 lb. friction drag prevent overtravel of the pencil, the spring alone serving to re- turn the pencil during the release of the Draft Gear Tests of the U. S. Railroad Administration 89 gear. The drum is covered with paper, and as the gear is compressed or released the pencil is moved correspondingly along the axis of the revolving drum, thus producing a time-closure diagram for the gear in car B. Tests were in each instance made with gears in both cars and again with a gear regularly, others, particularly those from friction gears of high capacity, are often closed by a succession of alternating move- ments or jerks. This will be shown as the individual cards are reproduced. The lower capacity gears naturally show smoother gear action than those of higher capacity. In fact, without exception, the .15 .Bo TTme- Seconds _25g SEC. gEAR cycle .30 Fig. 50 — Specimen Time-Closure Curve Produced on Small Drum of Car B in car B only, car A in the latter case being fitted up with a solid steel block instead of a draft gear. The action of the individual gear can be best studied under these latter conditions because it is definitely known that any irregularities recorded are due to the particular gear. In the former case the record does not determine which of the two opposing gears is responsible for the ir- regularities. Such irregular action is al- most invariably recorded when both cars are equipped with gears. The specimen card reproduced in Fig. 50 was made from the gear in car B when each car was equipped with a friction draft gear. This card shows the typical action of friction gears in the double-gear tests, or when both cars are equipped with gears. By means of these cards it is found that while some draft gears act smoothly and high capacity gears show jerks and irregu- larities in the compression line of the time-closure diagrams. This, in the single gear tests, is believed to be due largely to the pulsations or periodic vibrations be- tween the two cars resulting from the high forces incident to a high capacity gear with short travel. The cards show that with a gear in each car, the two gears do not work in harmony; that frequently on compres- sion, and almost invariably on the release, one gear will work for a while and then the other one will operate. From this it is concluded that twin arrangement of fric- tion draft gears is 1 not permissible. Seismograph Readings Each of the test cars is equipped with a pendulum device, secured to the side of the car, and so arranged that the retarda- 90 Draft Gear Tests of the U. S. Railroad Administration Fie. 49 — Instrument on Car B for Recording Draft Gear Action Draft Gear Tests of the U. S. Railroad Administration 91 Fig. 51 — Seismocraph of Car A tion or acceleration of the cars will cause the pendulums to swing upward by virtue of the inertia of their own masses. Gradu- ated quadrants are arranged as guides for the pendulum weights, and a light friction runner is carried with the weight and is left standing upon the guide at the highest point reached by the pendulum. The graduations are proportional to the verti- cal lift of the pendulum. Thus when the registration is 4.0 the pendulum has reached a vertical displacement twice as great as when the registration is 2.0. A photographic reproduction of the seismo- graph of car A is shown in Fig. 51. The seismograph records are usually attractive to the observer but are not of great im- portance in the study of gears. This is due primarily to the fact that the sides of the car have some movement with respect to the center of the entire mass. The quick vibrations of the side of the car appear also to influence the seismograph readings. These instruments are frequently spoken of as "shift gages." Graphs of Car Action As the final study of draft gear action must lie in a study of the results of the use of the gear upon the car and its lading, arrangements were made to obtain a com-' plete and accurate record of the perform- ance of both cars during the brief period of the draft cycle. A recording apparatus, arranged to draw simultaneous time-dis- placement curves of both cars, was de- signed and installed and a system of cer- tain reference lines worked out whereby these curves could be later so super-im- posed that at any instant during the draft gear cycle an exact knowledge of the per- formance of both cars could be had. These curves are commonly referred to as "car- movement curves." Photographic repro- ductions of the instruments for producing these curves are shown in Figs. 52 and 53. The apparatus has two drums mounted upon a common shaft and is placed on a stand alongside of the track. Each drum is 20.05 in. in circumference over the paper, and 30 in. long. The axis of the shaft is parallel to the track and the drums are so mounted upon the, shaft that one drum is alongside of the striking end of car A and the other alongside of the struck end of car B. Each drum has a pencil car- riage that is moved lengthwise of the drum by the movement of the car, each car hav- ing a pencil-propelling plunger attached to its side sill (see Figs. 49-52-53). Suit- able angle iron guides are arranged upon the instrument stand to cause the plungers to move into or out of engagement with he pencil carriages at the proper times. Making a Test Run In making a test the first operation is oroperly to apply the test gears to the cars. Care is taken to so adjust the length of the draft gear pockets that the gears will be held to their proper lengths. It is some- 92 Draft Gear Tests of the U. S. Railroad Administration u — — Draft Gear Tests of the U. S. Railroad Administration 93 Fig. 53 — Another View of Instrument for Recording Car Action 94 Draft Gear Tests of the U. S. Railroad Administration times necessary to apply liners behind the gear in order to accomplish this. After applying the gears to the cars, it is the practice to make ten preliminary runs at just slightly below the dosing speed, in order to condition the gears before mak- ing the regular runs. Car B is then spotted, always at the same definite station along the track. Car A is also spotted, the buffing faces of the couplers being just in contact and all loose slack being eliminated or compensated for. With the cars so spotted and with the A and B pencils in positions on their respective drums corresponding with the positions of cars A and B re- spectively, the drums are rotated a few times, thereby drawing the datum lines, A- A for car A, and B-B for car B (see Figs. 54 and 55). At the same time the small drum is rotated a few times so that its pencil draws the datum lines for this rec- ord (see Fig. 50) . It will thus be seen that all of the datum lines are drawn with the cars and gears in position as at the first instant of impact; or, in other words, at the beginning of a true gear compression. Ac- cordingly, in comparing the cards, it is definitely known that all car movements and gear action can be compared from these common datum lines. Without rotating the drums, each of the pencils is given a slight longitudinal move- ment, in order to draw the reference lines D-D and E-E on the A and B cards re- spectively (see Figs. 54 and 55). The pencil for car B is left standing exactly upon the datum lines B-B, or in other words, in position so that the first move- ment of car B will move this pencil along drum B. Car A is then drawn away from car B and the pencil for car A is drawn along the axis of drum A in order that the approaching car A may propel this pencil for some distance before the pencil reaches the datum line A-A, or the position where the two cars first meet. By this means the exact impact velocity of car A is de- termined, the speed of rotation of the drums being known. In order to obtain as nearly as possible the desired velocity, "the trip is set at a prescribed point along the in- clined portion of the track. The velocity developed from any station varies from time to time, hence, the exact velocity of impact must be determined for each run from the line drawn by car A below the datum line A-A. As car A approaches car B, all of the drums are set in motion, care being taken to start the instruments a sufficient time in advance to get the drums up to constant speed before the pencils are moved. In the record from drum A reproduced in Fig. 54 the pencil was stationed at a posi- tion represented by the line F-F, until the approaching car picked up the pencil and began to propel it along the axis of the drum. The angular line drawn by the pencil between the lines F-F and A-A de- notes the velocity of car A, the paper speed being known. This line being straight shows that the drums rotated at a constant speed. From the preliminary set-up of the cars and instruments it is known that when pencil A reaches the position of the line A-A on this drum, the cars have just met, for as previously explained, the datum line A-A was established prior to the tests for indicating the position of this pencil along the drum at the first instant of impact. As car A propels the pencil beyond the line A-A it is known that the draft gear cycle has begun, and from the convexity of the curve it can be seen that the velocity of car A is being reduced, due to the resistance of the gears. At the instant when the cars first met, or when this car-movement curve crosses the datum line A-A, it will be seen that the pencil was 3% in. from the reference line D-D. It is known that at this instant the B pencil was exactly the same distance Draft Gear Tests of the U. S. Railroad Administration 95 "* Q REFERENCE LINF — A =*'" » 3 2 X pDATi/M Line A a F / / ^-CARS MET X D x u X > x o / .2 x of x < x u F x Paper Traveled 34.1 "per Sec. Fig. 54 — Specimen Car-Movement Card from Drum A - U i h ? U in DC < B ^*>"*' ^-Datum Line B REFERENCE LINE "• M ^ Paper traveled 34.1" per Sec. J 2 Fig. 55 — Specimen Car-Movement Card from Drum B 96 Draft Gear Tests of the U. S. Railroad Administration from its reference line E-E, for these refer- ence lines were previously drawn to denote the relative positions of the two pencils or the datum lines. It will be noted from card B, Fig. 55, that a small interval of time elapsed before car B began to move out of its spotted position, the gears in the meanwhile compressing. When it began to move, its velocity gradually increased as shown by the concavity of the curve. By means of the datum and reference lines on these two cards a system of super- imposition of the two curves has been de- veloped and in Fig. 56 these curves have been so superimposed. This is done by matching up both the datum and reference lines and tracing one curve upon the other. The exact meeting point of the cars is thus established for both curves and both are also synchronized as to time. Consequently both the velocity of the cars and their rela- tive positions can be determined for any instant. And at any instant, also, the dis- tance either car has moved from its spotted positions is known. It will be seen that car A, during the first portion of the draft gear cycle continued to travel at a higher vel- ocity than car B. As car A thus encroaches upon car B the draft gears are compressed, the distance betwen the two super-imposed curves representing draft gear compression, together with the slight yield of the car bodies. Car A continued to run down upon car B, its velocity gradually decreasing and the velocity of car B gradually increasing due to the draft gear forces exerted be- tween the cars, until both cars were of equal velocity. This point corresponds with the point of maximum draft gear com- pression and can be readily determined by finding the maximum ordinate between the two curves. From this point on, the ve- locity of car B becomes greater than that of car A due to the forces of draft gear re- coil between the cars. Consquently, car B moves away from car A, allowing the draft gears to continue their release. At the point where the two curves cross there is no relative displacement of the two cars, or in other words, each car has travelled the same distance from its datum line, and it is therefore definitely known that at this instant the cars parted and that the draft gear cycle was completed. From the superimposed curves, Fig. 56, it is possible to obtain a wide range of in- formation concerning car action and draft gear action. The dotted line erected upon the datum line, for example, shows the movement of the two draft gears during compression and release. This curve is obtained by the simple process of stepping off the ordinates between the two curves upon the datum line as a base. The point where this draft gear curve reaches its maximum height is the point of maximum draft gear compression, and a vertical line has been drawn to indicate this point on the curves. From this it is then seen that the period of draft gear compression was 0.090 seconds and the period of release 0.166 seconds, the entire draft gear cycle, or the total length of time the cars were in contact being 0.256 seconds. At the instant of maximum draft gear compression, car A had moved 2.52 in. along the track from the point of impact* while car B had moved but 0.42 in., car A thus having encroached upon car B for 2.10 in., causing a corresponding amount of gear closure. At this instant, car A ceased encroaching upon car B, as shown by the falling off in gear closure. At the instant of maximum gear closure the ve- locities of the cars were equal, and the lines established tangential to the car-move- ment curves at this point denote the com- mon velocity at this instant. These tangen- tial lines also indicate the paths of the car- movement curves had there been no force of recoil, or if the draft gears had stuck. Angles have been drawn in to indicate the Draft Gear Tests of the U. S. Railroad Administration 97 98 Draft Gear Tests of the U. S. Railroad Administration influence of gear compression and gear re- lease, and the dimension of 4.25 in. shows the track movement of the cars during the entire draft gear cycle. The card of Fig. 50 was drawn by the action of the draft gear in car B during this same run. It will be seen that this gear closed 1.06 in., thus showing that the gear in car A closed 1.04 in. While the line in Fig. 56, representing the sum of the ac- tions of the two gears is smooth and regu- lar, yet the individual gears did not operate so regularly. The compression and re- lease was attained by first one gear operat- ing and then the other. This is to be ex- pected from friction gears and indicates variations in the effective co-efficient of friction. No special demerit is attached to this action of a friction gear, as either one gear or the other is operating at all times. It is important to have an exact record of the paper speed and especially important that there shall be no variations in speed during a run. To this latter end, the elec- tric current for operating drums A and B was supplied by a set of twenty-four Edi- son batteries which were frequently re- charged, and as no other current was drawn from these cells the speed of the drums was kept practically constant. The speed, how- ever, was checked at frequent intervals to guard against errors in this respect. With a definite knowledge in each instance of the paper speed, it is possible to establish the time ordinates, and from this scale is deduced the time interval required to close the draft gears and the time interval for the release of the gears, the sum of these two intervals being designated throughout this report as the "draft gear cycle." The paper speed ranged around 34 in. per sec- ond throughout the tests, but the exact speed was known for each individual test. The time scale is, of course, necessary for determining car velocities, and from the superimposed curves it is a simple matter to determine the exact impact velocity of car A and also the exact velocities of both cars at the instant of parting. It is also possible to determine by tangents the change in velocity of each car during any period of draft gear compression or release. It is further possible to plot curves showing the instantaneous velocity of both cars, and from these it is a matter of simple calculation to produce curves showing the instantaneous energies in the two cars. From the rate of change of velocity, the mean or average forces working between the two cars throughout the period of impact may be computed and a continuous time-force curve plotted. By stepping off and plotting the vertical distances between the superimposed car- movement curves as heretofore explained, a time-closure curve of draft gear action can be produced. This curve will show the complete draft gear action, both compres- sion and release, plotted against time, and in cases where a gear is used in car B only, the curve will practically coincide with the curve drawn by the small drum on car B. This erected time-closure curve, how- ever, includes not only the yield of the draft gears but has added to this the yield of the two car bodies. In this connection, it should be remembered that any yield of the car body constitutes additional draft gear action. By combining the time-closure curve and the time-force curve, the time element being eliminated, there can be pro- duced a force-closure curve which corres- ponds with the ordinary static curve of draft gear testing, although produced from actual operation of the gear during impact. A large number of runs were made for each type of gear but the limitations of space and the labor of working them up in complete form do not permit the repro- duction of all of them in the report. The uniform practice has been followed of Draft Gear Tests of the U. S. Railroad Administration 99 working up and reproducing for each type of gear the following runs: 1. A run, made at or near the closing point, with a calibrated test gear in car B only, car A being equipped with a solid steel block instead of a draft gear. 2. A run made at approximately one mile per hour, each car being equipped with a calibrated test gear. 3. A run made at or near the closing point, each car being equipped with a calibrated test gear. The first of these is worked up primarily that the action of a single calibrated gear in the car-impact tests may be compared with the action of the same gear in all of the laboratory tests, the possible influence of a second gear being removed. The sec- ond is worked up that a complete knowl- edge may be had of the action of each type of gear at low impact speeds. These low speed runs are especially useful in a study of train starting. The third is worked up as showing the best that may be expected from each type of gear at the maximum impact speed it is capable of cushioning, and gives the true comparison of the gears from the standpoint of yard service. The same gears of a type were used throughout the test, the general practice being to first make tests with both cars equipped, and then after replacing the gear in car A with the solid block, to make the single gear tests. Study of Curves A variety of interesting curves may be derived from the car-movement curves, but the essential features of the functioning of the gears will be shown in the following, which are reproduced for each of the three runs for each type of gear. Master Curves Car-Movement Curves — Superimposed. Derived Curves Velocity Curves. Energy Curves. Time-Force Curves. Time-Closure Curves. Force-Closure Curves. Throughout the report the curves have been reproduced to the same scale, so that the action of the different gears may be directly compared. The curves of the West- inghouse D-3 gear will be used for pur- poses of general description. Car-Movement Curves — Superimposed In tracing and reproducing the car-move- ment curves for publication it is not pos- sible to bring out all of the small variations and irregularities. In many instances these curves, although appearing smooth and reg- ular to the eye, contain numerous percepti- ble variations in the originals. All of the derived curves were produced directly from the originals and hence in the further studies of the gears the presence of any ir- regularities will be seen. The arms for producing the car-movement curves were attached to the side sills of the cars and al- though these test cars are equipped with two complete sets of diagonal braces, yet in severe buffing there is some movement of the side sill relative to the center sill and always more or less vibration. The ir- regularities in the car-movement curves are therefore due in a large measure to the vi- bration or to the relative movement of the side sills. The effect of these vibrations upon the car-movement curves, the full sig- nificance of which is brought out forcibly in the derived velocity curves, is probably the best comparative measure of the smooth- ness of action of the draft gears that can be obtained, for the smoother the action of the gear the more gradual and regular will be the transfer of energy from the striking car to the standing car and the less 100 Draft Gear Tests of the U. S. Railroad Administration will be the vibrations of the car structure. The superimposed car-movement curves, Fig. 80a, were made when car A was equipped with a solid steel buffer and car B with test gear No. 2. These curves rep- resent the closing run for a single West- inghouse type D-3 gear, the exact speed of impact being 2.68 M. P. H. At parting, car A had a speed of 0.74 M.P.H. and car B, 1.84 M.P.H. The instant of maximum gear compression, or in other words, the instant where the cars were of equal ve- locity, occurred 0.084 seconds after the first instant of impact. It required 0.166 seconds for the draft gears to release, or for the cars to part. The duration of the entire draft gear cycle was 0.25 seconds. The combined draft gear closure and car body yield, which includes the movement of the side sills of the cars, amounted to 2.65 in., this being the maximum ordinate between the two curves. At this instant car B had moved but 0.62 in. and car A, 3.24 in. along the track. Incidentally, throughout these tests, it has been found that the draft gears are closed and the maximum force developed between the cars before car B moves any material distance. Each of the cars moved 5.07 in. along the track while in contact, or during the com- plete draft gear cycle. Velocity Curves Fig. 80d shows the derived velocity curves for the single gear run of the West- inghouse D-3 gear at the closing speed. The irregular dotted line shows the exact first derivatives of the car-movement curves, the first derivative being instantaneous ve- locities. Any slight irregularity in the car-movement curve becomes very appar- ent in this differentiation. The curves for the Westinghouse D-3 gears are unusually smooth for its capacity. The impact velocity of car A in this run was 3.93 feet per second (2.68 M.P.H.), the velocity of car B at this instant being zero. As the gears compressed, the ve- locity of car A decreased and the velocity of car B increased until at the instant of maximum gear compression both cars were of the same velocity, namely, 1.92 feet per second. The result of the closing of this gear, therefore, was to reduce the velocity of car A from 3.93 feet per second to 1.92 feet per second. The remainder of the change in velocity of the two cars is due to the recoil of the gear, the effect of the recoil being to increase the velocity of car B to 2.69 feet per second and to still further reduce the velocity of car A to 1.08 feet per second at parting. The velocities represented by the irregu- lar dotted lines are true representations of the actual velocities of the side sills of the cars with respect to a stationary point along the track. It is not to be understood, how- ever, that the entire masses of the cars fol- lowed these velocity changes. Even though well constructed, these cars, like all others, are elastic and subject to more or less yield and vibration of parts. The irregularities in the velocity curves are accordingly due largely to the local surging and vibrations of the side sills. The frequency and am- plitude of the irregularities are a direct comparison of the results of the use of the various gears upon the cars. Thus it will be seen that with a spring draft gear, and with some of the lower capacity friction gears, the transfer of motion from one car to the other is effected with practically no disturbance of the car structure, the ve- locity curves being relatively smooth. On the other hand, with the higher capacity gears, considerable vibrations are set up. It is not to be expected that a gear func- tioning up to, say, 4 miles per hour, will give as smooth and regular a velocity curve at its closing speed as one functioning only to 2 miles per hour. The point of real in- terest is to compare the relative smoothness Draft Gear Tests of the U. S. Railroad Administration 101 of these curves from gears of the same ca- pacities and at approximately the same im- pact speed. It is not possible to obtain a true velocity record of an ordinary car from any one of its parts. Local vibrations and surges oc- cur in every particle of the car, even in the center sills. It would be possible to record the change in velocity of a car if it were constructed of a solid block, as of cast iron or cast steel, for in such a structure the vibrations would be so small as to be negligible. In such a test it should be pos- sible to determine draft gear resistance to a nicety. But because of the very fact that with a cast iron car vibrations and elastic yield are practically impossible, such an outfit is unfit for the test. Compressing a gear between two inelastic cars will not per- mit the development of the very things, viz., irregularity of gear action, that are being searched for. For if the structure, the inertia of which resists the compression of the gear, is incapable of yielding and vibrating, then the tendency of the gear to produce and to follow such vibrations in test action will be prevented, and any gear, unless of the most erratic nature, will pro- duce a smooth closure curve. This fact makes it imperative that draft gears should be tested upon actual cars so that if a gear has a tendency to pinch and bind on com- pression, it will be developed and dis- covered. It should be remembered that these car- body vibrations are a product of the in- dividual car and that each car will produce its own variations in velocity curves, due to the peculiarities of the particular car construction. Further, these vibrations in the velocity curves should not be inter- preted as meaning that the side sills of the cars vibrated through such distance. They represent instantaneous changes in velocity and the actual movement of the side sills that occurred were very slight; in many in- stances barely more than a tremble and seldom more than y% in. Mean velocity curves, shown in full lines, have been es- tablished from the general trend of the original car-movement curves, and these represent, as closely as it is practical to ob- tain, the true mean velocity of the entire mass of the car. This mean velocity curve is used throughout the remainder of the cards for the determination of energy and force. An interesting point in connection with the vibration of the cars was experienced when first developing the instruments at the Symington test plant. The first car- movement curves attempted were exceed- ingly irregular and showed a continuous series of waves, even when using spring draft gears at low impact speeds. These waves were found to be due to the longi- tudinal vibrations of the car body and truck bolsters upon the truck springs. Liners were applied between the truck bol- sters and the bolster guides of the truck side frames to prevent this vibratory move- ment upon the springs, but at the same time allowing vertical movement. The next suc- ceeding runs were smooth. ' It is recognized that in producing this artificial rigidity be- tween bolsters and side frames, the action of all the gears may have been very slightly smoothed out. For the surging of the body upon the truck springs might under some circumstances be reflected in the action of the gear. The production of the velocity curves from the car-movement curves, and espe- cially the showing of all the variations, was made possible by the use of a mechanical differentiating machine devised and built by Mr. Armin Elmendorf, formerly pro- fessor at the University of Wisconsin, and at present consulting engineer, with offices at 819 Chamber of Commerce Building, Chicago. Mr. Elmendorf has been promi- nent in the art of mechanical differentiation, 102 Draft Gear Tests of the U. S. Railroad Administration two of his papers on the subject appearing in the Journal of the Franklin Institute for January and February, 1918. The differ- entiating machine is based on the principle of similar triangles, a large triangle al- ways being developed similar to a smaller differential triangle. The angle of the lat- ter being varied according to the tangent of the car-movement curve causes a similar change in the larger, or plotting triangle, and the instantaneous velocity is thus plot- ted continuously and directly from the original car-movement curves, and with a much greater degree of accuracy than is possible by laying off tangents. This same instrument was also used to produce the time-force curves directly from the velocity curves. The instrument is invaluable for determining mechanically the first deriva- tive of any curve. A photographic repro- duction of this instrument is shown in Fig. 57. Energy Curves The energy curves shown in Fig. 80g have been produced by simple calculation from the preceding velocity curves. These energy values include not only the kinetic energy represented by the direct movement of the car as a whole, but also the energy of rotation of the wheels and axles, which in these cars amounts to an addition of 2.83 per cent to the ordinarily considered energy of translation. The total kinetic energy in one of these cars (143,000 lb. gross weight) including the above rotative energy, may be conveniently determined by the formula 4918 V 2 , V being the car velocity in miles per hour. In this particular run (Westinghouse D-3 single gear at closing speed) the kin- etic energy of car A was reduced from 35,308 ft. lb. to 8,427 ft. lb. by the com- pression of the gear, while at the same time the kinetic energy of car B was increased from zero to 8,427 ft. lb. The sum of the kinetic energies of the cars at this instant, (the instant of maximum draft gear com- pression) amounted to 16,854 ft. lb., so that the work done in compressing the draft gear and the car structure, and in over- coming rolling and grade resistance, amounted to 18,454 ft. lb. This quantity corresponds with the expression "work done" as applied to drop testing of draft gears. The dotted line beneath the line of zero energy represents the instantaneous value of work done at any instant during draft gear compression up to the instant of maximum draft gear closure. The energy curves during the period of draft gear release show the changes in kinetic energy produced in the cars by the recoil of the draft gear. In this particular run the recoil increased the kinetic energy of car A to 16,542 ft. lb. and reduced that of car B to 2,666 ft. lb., so that at the in- stant of parting the kinetic energy repre- sented by the movement of the two cars amounted to 19,208 ft. lb. The original kinetic energy of car A being 35,308 ft. lb., there was thus a total absorption in this run of 16,100 ft. lb., this quantity corresponding with the expression "work absorbed" as applied to drop testing of gears. The greatest possible absorption that could have taken place is always repre- sented by the maximum ordinate to the dotted curve beneath the line of zero en- ergy, and this point always coincides with the instant of maximum draft gear com- pression. During the period of compres- sion the sum of the kinetic energies of the two cars is decreasing, a portion of it being stored or absorbed by the draft gear. Dur- ing the period of release the draft gear re- turns more or less of this stored energy to the cars so that the sum of the kinetic en- ergies of the two cars is gradually increas- ing during the period of release. The giv- ing back of this energy is the measure of Draft Gear Tests of the U. S. Railroad Administration 103 absorption of the gear. In a gear of 100 result of this influence is separated from per cent absorption the dotted line would be horizontal throughout the release per- iod. In a perfect spring gear (no absorp- tion) the dotted line would be directed up- ward during this period, reaching the zero line at the instant of parting. true gear absorption. Time-Force Curves Fig. 80k shows the mean forces which develop between the two cars due to draft gear compression and release. The force is rs^. fllll^^ X V' * "\ i/ ^y y ^Kk Fig. 57 — Mechanical Differentiating Machine The maximum possible absorption of this run, therefore, was not the full energy of impact, 35,308 ft. lb., but 18,454 ft. lb., the work done in closing the gear; and as the absorption amounted to 16,100 ft. lb., the percentage of gear absorption in this run was 87.2 per cent. Some slight amount of this absortion was due to car resistance. In the tabulations (Figs. 62 and 64) the plotted against time, and the curve thus shows the building up of the force through- out the period of compression, to a peak at the point of maximum gear closure. Dur- ing the release period the force falls off suddenly in the case of a friction gear. The portion of the time-force curve to the left of the peak denotes mean draft gear 104 Draft Gear Tests of the U. S. Railroad Administration compression forces while that to the right denotes the forces of release. In the absence of any more workable and reliable method, the force has been ob- tained by calculating the forces required to produce the recorded changes of ve- locity over a given period of time, using the commonly understood laws of motion. It is admitted that the force as determined is deduced from its effect and has not been directly measured. No means for directly measuring a dynamic force has ever been devised. Various methods of a more or less refined nature have been employed to de- ductively determine the force from one or another of its results. Among the simplest and most elementary of these methods is the deduction of the force from the ac- celeration of a moving body. The possi- bility of error must be recognized in this method of figuring. In fact, any effort to compute a force from the result of the force assumes a constancy and uniform continuance over some accepted period of time that is especially questionable in the case of draft gear resistance. Such an as- sumption does not recognize the probable presence of a succession of higher forces working through lesser periods of time which would be capable of producing and would produce the identical records as to acceleration as a considerably lower force working uninterruptedly over a longer per- iod of time. It is unquestionable that in many of the gears, probably in every case, the sticking and irregularity of gear clos- ure was accompanied by high forces which, because of their very limited duration, could not manifest themselves in the time- displacement curves. Such forces would produce a momentary penetration or over- compression of the car sills, and the very storing and release of this would in itself smooth out the car-movement curves. The mean or average forces and the ultimate peak forces as deduced in these curves, however, are substantially correct and it is questionable whether after all the mean force as depicted, or in other words the force supplied over a long enough period of time to produce penetration or to do the work of rupture, is not the real damaging factor. For the high force of but momen- tary duration could possibly do little more than to overcome the inertia of the contig- uous particles of the sills to which the force is first applied. The time-force curves will assist in an understanding of the fact that the force be- tween colliding cars is not governed or in any manner reduced by the action of a fric- tion gear over a spring gear of the same characteristics. Energy absorption has in itself no effect whatever upon the compres- sion line. But its influence is immediately apparent in the forces of release. For while it requires high forces to overcome the fric- tional resistance and to compress* a friction gear, the force immediately disappears when the gear starts to release. This ac- tion is clearly shown in the time-force curves. While the peaks of each of these time- force curves show the maximum pressure finally developed between the cars in the particular run, these peaks are not to be considered as the closing forces of the gear. This force is usually higher than the true ultimate resistance of the gear, due to the fact that it is not possible to control the car speeds delicately enough to just close the gears and not over-close them. A very slight over-solid speed will, in a sturdily constructed gear, produce an im- mediate increase in force, because of the very small yield of the gear housing. In the force-closure curves, which will be dis- cussed hereafter, the true force at the very point of gear closure is given and the re- sults of any slight over-closure are elimi- nated. It should not, however, be assumed from the foregoing that the closing speeds Draft Gear Tests of the U. S. Railroad Administration 105 as given for the various gears are only roughly approximate, as they were in all instances searched out by means of many runs at close intervals around the closing point. An over-solid velocity of even 0.05 M.P.H. will, with a rigid gear construction, greatly increase the momentary peak of this force curve. Time-Closure Curves Time-closure curves are developed for each of the runs, Fig. 80n showing such a curve for the single gear run for the West- inghouse D-3 gear. Curve D in this figure has been derived and erected from the superimposed car-movement curves and shows the full yield that took place be- tween the cars, including draft gear com- pression, center sill compression, and side sill movement. This yield is plotted against time. Curve C is obtained by sub- tracting from Curve D the amount of the center sill yield and side sill movement, this having been determined from runs made at low speeds when both cars were equipped with solid steel blocks instead of draft gears. Curve C therefore represents the amount of and nature of the true draft gear action, all other influences being elimi- nated. Curve B was obtained from an en- tirely different source, namely, from the small drum carried by car B for recording the action of the draft gear in that car (see Figs. 49 and 50). Curves C and B show a remarkable coincidence for all of the gears, incidentally forming a valuable check upon the action of the entire set of recording in- struments. From the time-closure curve it will be seen that the draft gear in this run actually compressed 2.40 in., the difference between this figure and the nominal travel of 2 T 7 g in. being due to a shortness of £% in. in the length of the draft gear pocket in car B, the gear, in other words, being under g*5 in. more compression than normal. In general, throughout the tests, slight varia- tions will be found between the gear travels obtained in the car-impact tests and other tests. Such differences are due to the in- ability to adjust the gear to a nicety in the rough draft gear pockets of the cars. The actual point of gear closure was determined in each instance by the shearing of one or more lead records. The combined com- pression of the center sills and yield of the side sills of the two cars is represented by the maximum distance between the lines C and D, and in this particular instance amounted to 0.13 in. In the time-closure curve for the two Westinghouse gears, Fig. 80q, curves B, C and D are similar to curves B, C and D respectively of Fig. 80n. In this case, however, each car was equipped with a draft gear and the curve B, drawn by the draft gear of car B, shows the action of that gear only. Curve A has therefore been produced to show what the gear in car A was doing at the same time, these two curves when combined in the vertical scale producing curve C of the same figure. It will be seen that the two gears did not act in an entirely uniform manner, but that occa- sionally one of the gears would cease act- ing for an instant while the other moved. At other times both gears were acting. This character of action occurred both on compression and release, and was visible to the eye when closely watching the move- ment of the buffers. Force-Closure Curves In Fig. 80r is shown a force-closure curve for the closing run of Westinghouse D-3 gear (single gear run). This curve is produced directly from the time-force curve, Fig. 80r, and the time-closure curve, Fig. 80n, by the simple method of elimi- nating the time element from both of these curves and plotting the force directly against gear closure. This diagram cor- 106 Draft Gear Tests of the U. S. Railroad Administration responds with the ordinary static card ex- cept that it represents the dynamic action of the gear. All of the force-closure dia- grams are drawn to the same scale as the static test diagrams, so that the dynamic and static force-closure cards may be di- rectly compared for the same gears. For example, this dynamic card, Fig. 80r, should be compared with the static card shown in Fig. 18 for the identical gear (test gear No. 2). These curves provide a valuable check upon the fact of complete gear closure. In this particular run a peak force of 207,000 lb. was finally developed between the cars, but from the force-closure curve, Fig. 80r, it will be seen that the peak was reached when the gear was slightly over-solid and that the true solid point of the gear was at a load of 170,000 lb. This latter should therefore be taken as the ultimate dynamic resistance of this particular gear and is the true comparati/e measure of the load imposed upon the car sills at the instant of gear closure. In all cases a gear was not considered fully closed until one or more lead wires were sheared, following the usual practice as in drop testing; hence in almost every instance a very slight over-solid speed resulted from this effort to credit each gear with its full value. It requires but a very slight impact directly upon the gear barrel or housing to produce a high force peak, especially in a sturdily con- structed gear. The amount of work done and work absorbed may be figured from this card in the same manner as from the ordinary static card, these figures being given in later tabulations. In the double gear runs, Fig. 80t, the two gears did not do equal amounts of work, as can be seen from the superimposed work diagrams. Solid Buffer Runs The collision of two cars must always result in more or less penetration or yield of the car structures, the amount of the yield being dependent upon the sturdiness of the cars. In the car-impact tests the car- movement curves are obtained from the side sills of the cars. The records, there- fore, are for the movements of the side sills with respect to a fixed point along the track (the datum lines on the drums). The records accordingly do not represent the true and exact movements of the entire masses of the cars, but include the vibra- tions and relative movements of the side sills with respect to the center sills. In order to ascertain the yield of the Syming- ton test cars under different forces a series of runs was made with both cars equipped with solid steel blocks, 24 sq. in. cross sec- tional area, instead of draft gears. These were made at approximate impact speeds of %, %, %, 1, 1%, 2, 2% and 3 miles per hour. Special arrangements were made to ob- tain independent records of the yield of the center sills and the whip of the side sills. Certain fundamental data have been set up from these runs as to the yield of the cen- ter sills, the whip of the side sills, and the forces between cars with no draft gears, or the forces that should be expected from over-solid velocities with any gear, pro- vided it is as strong a column as the D coupler. These runs also give information in regard to work done and work absorbed by the car bodies and the lading. The records from the runs at approximate speeds of 1 M.P.H. and 2 M.P.H., together with the derived curves, are reproduced in Fig. 58. These curves, while appearing very small in comparison with the later curves made with draft gears in the cars, are reproduced to the same scale as the lat- ter and are directly comparable as to mag- nitude. The exact impact velocity in the first of these runs was 1.06 M.P.H., and 1.95 Draft Gear Tests of the U. S. Railroad Administration 107 M.P.H. in the second. The period of con- tact was very short, the entire cycle being but 0.057 seconds in the first run and 0.063 seconds in the latter run. In the first run the cars were in contact for 0.53 inches and for 1.09 inches in the second run. In the first run the maximum force was reached when car B had moved but ■£% in. and in the second run when it had moved but % in. In the matter of energy absorption, in run No. 1 there was a possible absorption of 2764 ft. lb. and an actual absorption of 1775 ft. lb., or 64.2 per cent. In run No. 2 the possible absorption was 9357 ft. lb. and the actual absorption 7607 ft. lb., or 82.5 per cent. The curves, Figs. 59 and 60, have been plotted from the results of these runs. The first of these, Fig. 59, shows the combined yield of the two car bodies at various speeds of impact. The second, Fig. 60, shows the force developed between the cars at various speeds. These curves form the basis for the general deductions made for the influence of the car bodies throughout the tests. It should be remembered that these definite results are for the two par- ticular cars only, but it is believed that they are indicative of the performance of modern cars generally. Incidentally, this force-curve has been compared with a sim- ilar curve produced in an entirely different manner by Col. B. W. Dunn, Chief of the Bureau of Explosives, the two curves show- ing a remarkable coincidence. The yield of the car bodies and the whip of the side sills as determined in these runs form the basis for the corresponding corrections in the succeeding time-closure curves of the draft gears. 108 Draft Gear Tests of the U. S. Railroad Administration t: 2 /mpoci~ Ve/ocrf~y=/o6M.P.H. /mpae-f- \/e/oc/-ty=/3s m.p.h. Sec ^//f^ OJ4 _Sec^e/eose ■^ OS7 SecCyc^ ,,- ^gc Cycle h— 063 *■ m 7Tme- Seconds Fig. 58 — Curves from Solid Buffer Runs rorce- C/osure Diagrams. Impact Vthaty-/.OGMP.H. ,J4 ^j/s,ooo m I Car Y/e/d—/nctiv9. Force- C/osure Diagrams. -JO- | 1 * eco Mpac-f Ve/ocfty, ^/.SSMRH. 4Cd 1 1 300 1 I 2C0 f /CO I \t_ y Car- Y/e/d — /ncAea. Draft Gear Tests of the U. S. Railroad Administration 109 Y/ELD OF TEST CARS, WHEN COLUD/A/S,^/TROUT DRAFT SEARS. 0.1 0.6 as i? #&.- xt> ^ Jjs*^ *\t x^ ^O.J 3 .\os V A / yr 0.2 OJ / a /MPACT VELOC/TY- M.P.H. Fig. 59 — Plot of Car Body Yield at Varying Impact Velocities 110 Draft Gear Tests of the U. S. Railroad Administration FORCE BETWEEN TEST CARS, WHENCOLL/D/MG, W/TH OUT DRAFT GEARS. WOO /zoo i ^S { Of soo O / <0 600 / O O 6 • 400 0) *$r ^s 200 / 2. /MPACT VELOC/TY - M.RH. Fig. 60 — Plot of Force at Varying Impact Velocities DISCUSSION OF GEARS IN CAR-IMPACT TESTS As the first measure of a draft gear is its capacity, or reduced to terms of practice, the impact speed at which it will close, the performance of the several gears in the car- impact tests will be discussed in the order of the closing speeds of the test gears. The later tabulations also are arranged in this order. National H-l Gear No. 29 in Car B Gear No. 30, or Solid Buffer, in Car A These gears showed the highest capacity, both in the drop test and in the car-impact tests of any of the gears, and their action was good, considering the high closing speed. While the velocity curves show many slight irregularities, yet there were no violent disturbances. The closing run was at a velocity of 5.07 M.P.H., represent- ing almost eight times the energy of the closing run of the spring gear, and more than one and one-half times the energy of a run at 4 M.P.H., hence trembling of the car sides is to be expected. The gear ac- tion itself was not so smooth in the closing speed run, but the amount of gear action and the smoothness of car action at 1 M.P.H. with two of these gears is surpris- ing. The two test gears went solid at an impact velocity of 5.07 M.P.H. and the single gear at 3.95 M.P.H. At 1.14 M.P.H, with two gears, the combined gear closure was 1.25 in. In the final run the average work done per gear was 27,184 ft. lb, and the average work absorbed 20,750 ft. lb, or a gear absorption of 76 per cent. The total energy loss in the run from all causes was 51,461 ft. lb, or 41 per cent of the original kinetic energy of the striking car. In this connection it should be noted that if the gears themselves were of 100 per cent absorption efficiency, the percentage of energy loss in the run from gear absorp- tion could not amount to more than 50 per cent of the original kinetic energy of car A. The gears were slightly over-solid, as can be seen from the force-closure curves, the force peak reaching 820,000 lb. in the run, whereas gear No. 29 closed at 390,000 lb. and No. 30 at 550,000 lb. In all gears the closing point was determined by the shearing of lead wires and the regular practice was to just slightly exceed the capacity rather than to credit a gear with a reduced closing speed. But it should not be assumed that the run was far beyond the capacity of the gear, as in a sturdy gear such as the H-l a slight excess of energy delivered directly to the gear as a column will at once produce a high force peak. Based upon the average drop test value of this type of gear, a closing speed of 5.09 M.P.H. with 143,000 lb. cars may be ex- pected from two average commercial gears of this type, with a closing force of 466,000 lb. Sessions Type K Gear No. 11 in Car B Gear No. 12, or Solid Buffer, in Car A The action of these gears in the car-im- pact tests was not satisfactory. The gears closed in an irregular manner and the car movement curves are the roughest and most irregular obtained in the tests, indicating violent disturbance of the car and lading. The spring barrels of both gears scaled during the test and all of the springs had been solid. The two test gears closed at 4.37 M.P.H. and the single gear at 3.81 M.P.H. At 1.12 M.P.H, with two gears, the combined gear closure was 1.07 in, showing a satisfactory cushioning at this — Ill 112 Draft Gear Tests of the U. S. Railroad Administration speed. In the final run the average work done per gear was 19,367 ft. lb., and the average work absorbed 16,375 ft. lb., or a gear absorption of 84% per cent. The total energy loss in the run from all causes was 43,040 ft. lb., or 45 per cent of the original kinetic energy of the striking car. The gears were slightly over-solid, the force peak in the run reaching 400,000 lb., while gear No. 11 closed at 260,000 lb. and gear No. 12 at 165,000 lb. Based upon the average drop test value of this type of gear, a closing speed of 4.33 M.P.H. with 143,- 000 lb. cars, may be expected from two average commercial gears of this type, with a closing force of 210,000 lb. The velocity curves of this gear being especially irregular, it may be worth while to repeat here a previous notation regard- ing the mean velocity curves. After fol- lowing all the minute variations in the car movement curves with the mechanical dif- ferentiater and producing the irregular dotted curves, a second differentiation was made, following the trend of the car-move- ment curves rather than the local varia- tions. The mean velocity curves were estab- lished by this method. It is especially noticeable that the Ses- sions K gear, which in the drop test shows considerably less capacity than the Ses- sions Jumbo (18.8 in. Sessions K, 28.1 in. Sessions Jumbo), required an impact velocity of 4.40 M.P.H. to close two gears, whereas two Jumbo gears, to be discussed later, required a speed of but 4.22 M.P.H. Miner A-18-S Gear No. 23 in Car B Gear No. 24, or Solid Buffer, in Car A These gears showed high capacity in the car-impact tests. The car-movement curves show some irregularities and the derived velocity curves, while not smooth, are good for a run of this high speed. The gear ac- tion was good except when nearly closed, where some pulsations occurred. The two gears did not work uniformly, one being almost closed before the other had com- pressed more than y 8 in. This does not mean that at any time there was a lack of cushioning between the cars, as either one or the other of the two gears was yielding at all points of the gear cycle. Such alter- nating action between the two gears is typical of friction draft gears. Likewise on the release, the gears operated alter- nately but positively. The two test gears went solid at an impact velocity of 4.46 M.P.H. and the single gear at 3.57 M.P.H. At 1.06 M.P.H. with two gears the com- bined gear closure was 0.64 in. In the final run the average work done per gear was 18,717 ft. lb. and the average work absorbed 13,334 ft. lb., or a gear absorp- tion of 71 per cent. The total loss in the run from all causes was 40,990 ft. lb., or 42 per cent of the original kinetic energy of the striking car. The gears were slightly over-solid, as can be seen from the force- closure curves, the force peak reaching 640,000 lb. in the run, whereas gear No. 23 closed at 390,000 lb. and gear No. 24 at 390,000 lb. Based upon the average drop test value of this type of gear, a closing speed of 4.33 M.P.H. with 143,000 lb. cars may be expected from two average com- mercial gears of this type, with a closing force of 368,000 lb. Westinghouse NA-1 Gear No. 7 in Car B Gear No. 8, or Solid Buffer, in Car A The Westinghouse type NA-1 gears in the car-impact tests' were highly satisfac- tory. Both the gear action and the car action were especially smooth, although the two gears did not act together either on compression or release. The velocity curves show the least disturbance of cars and lad- ing found in any gear, except in the case Draft Gear Tests of the U. S. Railroad Administration 113 of a few of the very low capacity ones. The two test gears went solid at an impact velocity of 4.16 M.P.H. and the single gear at 3.06 M.P.H. At 0.96 M.P.H, with two gears, the combined gear closure was 1.62 in. In the final run the average work done per gear was 19,167 ft. lb. and the average work absorbed 16,717 ft. lb., or a gear absorption of 87 per cent. The total energy loss in the run from all causes was 39,370 ft. lb., or 46 per cent of the orig- inal kinetic energy of the striking car. The gears were slightly over-solid, as can be seen from the force-closure curves, the force peak reaching 500,000 lb. in the run, whereas gear No. 7 closed at 158,000 lb. and No. 8 at 187,000 lb. The curves made with this gear, which has 3 in. travel, show clearly the value of increased length of draft gear travel. Based upon the average drop test value of this type of gear, a clos- ing speed of 4.24 M.P.H. with 143,000 lb. cars may be expected from two average commercial gears of this type, with a clos- ing force of 179,000 lb. National M-l Gear No. 32 in Car B Gear No. 33, or Solid Buffer, in Car A These gears in the car-impact tests showed rather irregular gear action. The car-movement curves, however, are not bad considering the speed of the run, and the velocity curves do not indicate a violent disturbance of the cars. The two test gears went solid at an impact velocity of 4.26 M.P.H. and the single gear at 3.08 M.P.H. At 1.06 M.P.H., with two gears, the com- bined gear closure was 1.10 in. In the final run the average work done per gear was 20,000 ft. lb., and the average work absorbed 16,784 ft. lb., or a gear absorp- tion of 84 per cent. The total energy loss in the run from all causes was 40,312 ft. lb., or 45 per cent of the original kinetic energy of the striking car. The gears were slightly over-solid, as can be seen from the force-closure curves, the force peak reach- ing 580,000 lb. in the run, whereas gear No. 32 closed at 400,000 lb. and No. 33 at 218,000 lb. Based upon the average drop test value of this type of gear, a closing speed of 4.22 M.P.H. with 143,000 lb. cars may be expected from two average com- mercial gears, with a closing force of 303,- 000 lb. Sessions Jumbo Gear No. 14 in Car B Gear No. 15, or Solid Buffer, in Car A This gear made a much better showing in the car-impact tests than the previous Sessions K gear. In fact, for a gear of its capacity, its action is not unsatisfactory. This gear again demonstrates the value of longer gear travel. The two test gears closed at 4.30 M.P.H. and the single gear at 3.26 M.P.H. At 1.02 M.P.H., with two gears, the combined gear cjosure was 1.14 in. In the final run, with two gears, the average work done per gear was 19,025 ft. lb., and the average work absorbed 14,317 ft. lb., or a gear absorption of 75 per cent. The total energy loss in the run from all causes was 35,660 ft. lb., or 39 per cent of the original kinetic energy of the striking car. The gears were slightly over-solid, the force peak in the run reaching 465,000 lb., while gear No. 14 closed at 137,000 lb. and gear No. 15 at 250,000 lb. Based upon the average drop test value of this type of gear, a closing speed of 4.22 M.P.H. with 143,000 lb. cars may be expected from two average commercial gears, with a closing force of 186,000 lb. The relationship be- tween the drop tests and the car-impact tests of this gear is much closer than in the Sessions Type K. 114 Draft Gear Tests of the U. S. Railroad Administration National M-4 Gear No. 35 in Car B Gear No. 36, or Solid Buffer, in Car A The M-4 gear is the smoothest acting and most regular of the National gears, and also shows the highest percentage of ab- sorption. It also shows the lowest ultimate resistance. The individual gears did not work together, but the car-movement curves and the velocity curves, considering the impact velocity, are satisfactory. The two test gears went solid at an impact velocity of 4.12 M.P.H., and the single gear at 3.88 M.P.H. At 1.06 M.P.H., with two gears, the combined gear closure was 1.10 in. In the final run the average work done per gear was 18,467 ft. lb., and the average work absorbed 15,817 ft. lb., or a gear absorption of 86 per cent. The total energy loss in the run from all causes was 38,670 ft. lb., or 46 per cent of the original kinetic energy of the striking car. The gears were slightly over-solid, as can be seen from the force-closure curves, the force peak reach- ing 360,000 lb. in the run, whereas gear No. 35 closed at 159,000 lb. and No. 36 at 138,000 lb. Based upon the average drop test value of this type of gear, a closing speed of 4.03 M.P.H. with 143,000 lb. cars may be expected from two average com- mercial gears, with a closing force of 143,- 000 lb. Cardwell G-18-A Gear No. 20 in Car B Gear No. 21, or Solid Buffer, in Car A The action of these gears in the car-im- pact tests was satisfactory. The gear is of 3 i 3 (r in. travel and this is apparent in length of gear cycle and track movement of cars during the gear cycle. The G-18-A gears have less initial compression thantheG-25-A gears, and this is reflected in the greater yield of the two gears in the runs at ap- proximately 1 M.P.H. The two test gears went solid at an impact velocity of 3.85 M.P.H. and the single gear at 2.79 M.P.H. At 1.10 M.P.H., with two gears, the com- bined gear closure was 1.32 in. In the final run the average work done per gear was 17,117 ft. lb., and the average work absorbed 15,575 ft. lb., or a gear absorp- tion of 91 per cent. The total energy loss in the run from all causes was 35,476 ft. lb., or 49 per cent of the original kinetic energy of the striking car. The gears were slightly over-solid, as can be seen from the force-closure curves, the force peak reach- ing 295,000 lb. in the run, whereas gear No. 20 closed at 110,000 lb. and No. 21 at 186,000 lb. Based upon the average drop test value of this type of gear a closing speed of 3.89 M.P.H. with 143,000 lb. cars may be expected from two average com- mercial gears, with a closing force of 214,- 000 lb. Cardwell G-25-A Gear No. 17 in Car B Gear No. 18, or Solid Buffer, in Car A The test gears of this type were, as here- tofore explained, of higher capacity than commercial gears of the same type pre- viously tested. Consequently it required a higher impact velocity (4.05 M.P.H.) to close the two test gears than is to be ex- pected from the average product. But even though of abnormal capacity the Cardwell test gears showed smooth action both as to gears and cars. In fact, for its capacity, it stands in this respect as one of the most satisfactory of the gears. It is not to be expected that any gear of higher capacity will give the ease of car movement and the smoothness of gear action shown by spring gear with and at its lower capacity. But when a friction gear with a closing capacity of 4 M.P.H. and of 2% in. travel or less shows reasonably smooth velocity curves in Draft Gear Tests of the U. S. Railroad Administration 115 these tests, it may be accepted as a satis- factory gear so far as the service perform- ances of the new gear is concerned. The single test gear went solid at 2.97 M.P.H. At 0.92 M.P.H. the combined travel of the two gears was 0.60 in., reflecting the high initial compression of these gears. In the final run the average work done per gear was 17,917 ft. lb., and the average work absorbed 15,534 ft. lb., or a gear absorp- tion of 87 per cent. The total energy loss in this run from all causes was 38,190 ft. lb., or 47 per cent of the original kinetic energy of the striking car. These gears in the run at 4.05 M.P.H. were slightly over- solid. The force peak reached in the run was 368,000 lb., whereas gear No. 17 went solid at 295,000 lb. and gear No. 18 at 315,000 lb. Based upon the average drop test value of this type of gear, a closing speed of 3.86 M.P.H. (143,000 lb. cars) may be expected from two average com- mercial gears, with a closing force of 277,- 000 lb. Westinghouse D-3 Gear No. 2 in Car B Gear No. 3, or Solid Buffer, in Car A In all the runs the Westinghouse D-3 gear showed smooth and regular gear ac- tion and a noticeable absence of shock to cars and lading. The two gears closed at 3.65 M.P.H., and the single gear at 2.68 M.P.H. At 1.13 M.P.H., with two gears, the combined gear closure was 2.44 in., re- flecting the easy initial movement of this gear. The draft gear action, while slightly variable between the two gears in the double gear runs, is exceptionally good. The velocity curves are good for a friction gear of this capacity. In the final run the average work done per gear was 14,667 ft. lb., and the average work absorbed 12,167 ft. lb., or a gear absorption of 83 per cent. The total energy loss in this run from all causes was 29,864 ft. lb., or 46 per cent of the original kinetic energy of the striking car. The final run was just slightly over- solid, as can be seen from the force-closure diagram. The peak of the force curve reached 285,000 lb., gear No. 2 closing at 195,000 lb. and gear No. 3 at 240,000 lb. Based Upon the average drop test value of this type of gear a closing speed of 3.59 M.P.H. (143,000 lb. cars) may be expected from two average commercial gears, with a closing force of 210,000 lb. Gould 175 Gear No. 41 in Car B Gear No. 42, or Solid Buffer, in Car A The Gould gears showed smooth action, but high recoil. The two test gears closed at 3.56 M.P.H. and the single gear at 2.72 M.P.H. At 0.96 M.P.H., with two gears, the combined gear closure was 1.63 in. The velocity curves, while not bad, are yet more irregular than other gears of equal capacity. In the final run the average work done per gear was 13,767 ft. lb., and the average work absorbed 10,100 ft. lb., or a gear absorption of 73 per' cent. The total energy loss in this run from all causes was 24,523 ft. lb., or 39 per cent of the original kinetic energy of the striking car. These gears also were slightly over-solid, the force peak in the run reaching 405,000 lb. ; gear No. 41 closed at 260,000 lb. and gear No. 42 at 230,000 lb. Based upon the aver- age drop test value of this type of gear, a closing speed of 3.59 M.P.H. with 143,000 lb. cars may be expected from two average commercial gears, with a closing force of 249,000 lb. Murray H-25 Gear No. 38 in Car B Gear No. 39, or Solid Buffer, in Car A In the car-impact tests, as in all the tests of the full program, the Murray gear 116 Draft Gear Tests of the U. S. Railroad Administration showed exceptionally smooth and regular action. The car movement curves and velocity curves are among the best, consid- ering the speed of impact, and indicate that there was no violent disturbance of the cars and lading. The two test gears closed at a speed of 3.45 M.P.H. with the 143,000 lb. cars, and the single gear at 2.76 M.P.H. At 0.98 M.P.H. the combined travel of two gears was 0.92 in., reflecting the higher initial resistance of this gear. In the final run the average work done per gear was 13,900 ft. lb., and the average work ab- sorbed 11,584 ft. lb., or a gear absorption of 83 per cent. The total energy loss in this run from all causes was 27,730 ft. lb., or 47 per cent of the original kinetic energy of the striking car. The gears were slightly over-closed, the force of impact finally reaching a peak of 315,000 lb., gear No. 38 closing at 210,000 lb. and gear No. 39 at 130,000 lb. Based upon the average drop test value of this type of gear, a closing speed of 3.52 M.P.H. (143,000 lb. cars) may be expected from two average com- mercial gears, with a closing force of 227,000 lb. Christy Gear No. 52 in Car B Gear No. 53, or Solid Buffer, in Car A This gear, closing at a comparatively low speed, produced irregular and erratic gear closure curves and unsatisfactory car- movement curves'. Even the low speed runs were not smooth and regular as in most gears. The velocity curves indicate a vio- lent disturbance of the cars. The two test gears went solid at an impact velocity of 3.73 M.P.H. and the single gear at 3.56 M.P.H. At 1.06 M.P.H., with two gears, the combined gear closure was 0.84 in. In the final run the average work done per gear was 12,934 ft. lb., and the average work absorbed 10,909 ft. lb., or a gear absorption of 84 per cent. The total energy loss in the run from all causes was 32,026 ft. lb., or 47 per cent of the original kinetic energy of the striking car. The gears were slightly over-solid, as can be seen from the force-closure curves, the force peak reach- ing 370,000 lb. in the run, whereas gear No. 52 closed at 194,000 lb. and No. 53 at 150,000 lb. Based upon the average drop test value of this type, of gear, a closing speed of 3.50 M.P.H. with 143,000 lb. cars may be expected from two average com- mercial gears, with a closing force of 151,000 lb. Miner A-2-S Gear No. 26 in Car B Gear No. 27, or Solid Buffer, in Car A The Miner A-2-S gear showed good ac- tion but rather low capacity in the car- impact tests. Both the car action and gear action were especially smooth and among the most satisfactory in the tests. It is noticeable that in the final run with two gears, the gear in car A closed entirely be- fore the gear in car B began, to compress. The two test gears went solid at an impact velocity of 3.21 M.P.H. and the single gear at 2.47 M.P.H. At 1.07 M.P.H., with two gears, the combined gear closure was 0.81 in., reflecting the high initial resistance of these gears. In the final run the average work done per gear was 10,025 ft. lb. and the average work absorbed 8,417 ft. lb., or a gear absorption of 84 per cent. The total energy loss in the run from all causes was 24,754 ft. lb., or 49 per cent of the original kinetic energy of the striking car. The gears were slightly over-solid, as can be seen from the force-closure curves, the force peak reaching 525,000 lb. in the run, whereas gear No. 26 closed at 105,000 lb. and No. 27 at 68,000 lb. This high force peak, at a very slight excess of energy, re- flects the sturdy nature of the barrel of this gear when called upon to function as a Draft Gear Tests of the U. S. Railroad Administration 117 column in over-solid blows. Based upon the average drop test value of this type of gear, a closing speed of 3.26 M.P.H. with 143,000 lb. cars may be expected from two average commercial gears, with a closing force of 89,000 lb. Waugh Plate Type Gear No. 49 in Car B Gear No. 50, or Solid Buffer, in Car A The Waugh gear showed excellent re- sults in the car-impact tests, although its capacity is limited. The ease with which the standing car is set in motion, considered alone, must commend this gear. Even though showing a high ultimate force, the regularity with which the force is built up eases off the blow and prevents severe shocks and vibrations. The curves show, however, that the action is almost entirely spring action, the absorption being low. The two test gears went solid at an impact velocity of 3.02 M.P.H. and the final run of the single gear was at 1.94 M.P.H. The records from this run show, however, that the single gear was not solid at this speed and that the gear should have been given an impact at 2.20 M.P.H. to fully close the one gear. At 1.06 M.P.H., with two gears, the combined gear closure was 2.34 in., showing a very high yield at this low speed. In the final run the average work done per gear was 9,100 ft. lb., and the average work absorbed 4,117 ft. lb., or a gear absorption of 45 per cent. The total energy loss in the run from all causes was 10,818 ft. lb., or 24 per cent of the original kinetic energy of the striking car. The gears were just closed, as can be seen from the vertical direction of the force-closure curves. The force peak reached 335,000 lb. in the run, and gear No. 49 closed at this point. Gear No. 50 closed at 285,000 lb. Based upon the aver- age drop test value of this type of gear, a closing speed of 2.98 M.P.H. with 143,000 lb. cars may be expected from two average commercial gears, with a closing force of 302,000 lb. Bradford K Gear No. 46 in Car B Gear No. 47, or Solid Buffer, in Car A This gear in the car-impact tests showed the same unsatisfactory conditions as to the development of the design as in the pre- vious laboratory tests. The springs went solid before the housing came together, thus setting up abnormal wedging forces and high ultimate resistance. One of the rockers cracked during these tests. The gears were of low capacity, the curves showing almost entirely spring action with but little friction. This can be readily seen by comparing the compression and release periods of the gear cycle, which are almost equal. The two test gears went solid at an impact velocity of 2.78 M.P.H. and the single gear at 2.04 M.P.H. At 1.12 M.P.H., with two gears, the combined gear closure was 2.67 in., this being the maximum yield obtained from any of the gears in the low speed run. In the final run the average work done per gear was 6,833 ft. lb., and the average work absorbed 2,150 ft. lb., or a gear absorption of 31 per cent. The total energy loss in the run from all causes was 9,835 ft. lb., or 26 per cent of the original kinetic energy of the striking car. While the heads never came together, the gears were slightly over-solid on the springs, the force peak reaching 340,000 lb. in the run, whereas gear No. 46 closed at 270,000 lb. and No. 47 at 220,000 lb. In view of the defective design of this gear it is hardly proper to set values to be expected from the commercial gears from these test re- sults. But following the same methods used for grading all other gears, namely, based upon the average drop test value found for this type of gear, a closing speed 118 Draft Gear Tests of the U. S. Railroad Administration of 2.87 M.P.H. with 143,000 lb. cars may be expected from two average commercial gears, with a closing force of 252,000 lb. Harvey Springs Gear No. 55 in Gar B Gear No. 56, or Solid Buffer, in Car A Two 8 in. x 8 in. Harvey springs, throughout the tests, constituted one gear unit, and in the car-impact tests these springs were applied in twin fashion, one above the other, with a horizontal yoke. The gear action was reasonably smooth, but it is noticeable that most of the yield of the springs had taken place at 1 M.P.H. The car-impact tests of these springs show the same character of compression line as found in the static test and the gear absorp- tion shows furthermore that the high force is the result of friction. The two gears went solid, or reached the previously de- termined statically solid point of travel, at an impact velocity of 2.33 M.P.H. and the single gear at 1.97 M.P.H. At 1.02 M.P.H., with two gears, the combined gear closure was 2.62 in. In the final run the average work done per gear was 4,992 ft. lb., and the average work absorbed 2,709 ft. lb., or a gear absorption of 54 per cent. The total energy loss in the run from all causes was 8,074 ft. lb., or 30 per cent of the original kinetic energy of the striking car. The gears at this run had reached a solid condition, as can be seen from the vertical trend of the force-closure curves, and also from the increasing roughness of the car-movement curves and the irregu- larities at the top of the time-closure curves. The force peak reached 490,000 lb. in the run, whereas gear No. 55 closed at 245,000 lb. and No. 56 at 300,000 lb. Based upon the average drop test value of this type of gear, a closing speed of 2.27 M.P.H. with 143,000 lb. cars may be ex- pected from two commercial gears, with a closing force of 259,000 lb. Class G Coil Springs Gear No. 58 in Car B Gear No. 59, or Solid Buffer, in Car A Two Class G springs, throughout the tests, constituted one gear unit, and in the car-impact tests the springs were applied in twin fashion, one above the other, with a horizontal yoke. The coils were not pro- tected from going solid. The curves ob- tained from these springs represent the best action obtained, both as to gear action and smooth and gradual movement of the cars. From the velocity curves it will be seen that the cars were eased off with no vibrations or disturbance whatsoever. The capacity, however, is extremely limited and the spring recoil almost 100 per cent. It is of especial interest to note that car A came to rest by the time the cars parted, and that car B, at parting, had almost the initial velocity of car A, this indicating practi- cally total recoil of energy. Another point of interest, and also reflecting the absence of gear absorption, is that the time of draft gear release is practically the same as that of draft gear compression. In fact, if the car-movement curve of car A is reversed and laid upon that of car B the two curves will be found to almost coincide. The two test gears went solid at an im- pact velocity of 1.84 M.P.H. and the single gear at 1.45 M.P.H. At 1.07 M.P.H., with two gears, the combined gear closure was 2.00 in. In the final run the average work done per gear was 4,117 ft. lb., and the average work absorbed 450 ft. lb., or a gear absorption of 11 per cent. The total energy loss in the run from all causes was 2,205 ft. lb., or 13 per cent of the original kinetic energy of the striking car. The gears were just solid, as can be seen from the force-closure curves, the force peak Draft Gear Tests of the U. S. Railroad Administration 119 reaching 78,000 lb. in the run, whereas both gears closed at 60,000 lb. Based upon the average drop test value of this type of gear, a closing speed of 1.87 M.P.H. with 143,000 lb. cars may be expected from the use of two Class G springs per car, with a closing force of 62,000 lb. The spring gears were the final ones in the car-impact tests, the Westinghouse D-3 being the first. The excellence of both sets of runs is a check upon the uniform condi- tion of the cars and the instruments throughout the full series of tests. Summary of Car-Impact Tests It will be understood that the car-impact tests were made upon two gears only of each type. The table, Fig. 61, shows in Columns 3 and 4 the drop test values of the two test gears used for this purpose and of two average commercial gears respec- tively. In Columns 5 and 6 are then given the closing speeds of the two test gears and the closing speed that may be expected from two commercial gears. This latter quantity is based upon the relative drop test values of the test gears and the com- mercial gears. The three general tabula- tions, Figs. 62, 63 and 64, have been pre- pared to summarize the actual performance of the test gears in the car-impact tests. In these tabulations the gears appear in the order of the closing speeds of the com- mercial gears and have been classified ac- cording to closing speeds. In studying the performance of the car and the action of the gears there is but little interest in com- paring a low speed gear with a high speed gear. The interest lies in comparing the action of and the results from the use of gears of different types and of approxi- mately equal capacities. The gears have accordingly been grouped in these and suc- ceeding tables into four classes, as follows: Class 1: Gears closing at 5 M.P.H. and over. National Type H-l. Class 2: Gears closing at from 4 to 5 M.P.H. Sessions Type K. Miner Type A-18-S. Westinghouse Type NA-1. National Type M-l. Sessions Jumbo. National Type M-4. Class 3: Gears closing at from 3 to 4 M.P.H. Cardwell Type G-18-A. Cardwell Type G-25-A. Westinghouse Type D-3. Gould Type 175. Christy. Miner Type A-2-S. Class 4: Gears closing at less than 3 M.P.H. Waugh Plate. Bradford Type K. Harvey, two 8 in. x 8 in. springs, Coil Springs, two 8 in x 8 in., Class G. In the above classification of gears it will be noticed that while the Cardwell G-25-A test gears actually closed at 4.05 M.P.H., yet from the table, Fig. 61, it will be seen that the average commercial gears of this type properly fall in Class 3, and this gear has accordingly been entered in this class in the general tabulations. Like- wise the test gears of the Waugh type ac- tually required 3.02 M.P.H. to close them, but from the average commercial gear this type belongs in Class 4. Asterisks (*) have been placed opposite these gears in the tables because of this fact. The table, Fig. 62, gives the results of the car-impact tests at the closing speed runs, using a test gear in each car; that of Fig. 63 the results at impact velocities of approximately 1 M.P.H. with a test gear in each car; and that of Fig. 64 the results at the closing speed runs with a test gear in car B only, car A being equipped with a solid steel block instead of a draft gear. These tables need no especial explanation 120 Draft Gear Tests of the U. S. Railroad Administration except that it will again be stated that the results as tabulated are for test gears. The comparative action of average commercial gears, from which gear ratings should be deduced, are shown in a later table, Fig. 67. One of the most noticeable facts brought out by the general action of the gears in the car-impact tests is that draft gears are closed and the maximum force is delivered to the cars before the standing car (car B) has moved any material distance along the track. The maximum distance car B had moved in any of the tests at the instant of maximum force was with the Sessions Jumbo gear, and amounted to 1.59 in. From this it decreased to 0.43 in. with the Harvey springs. This shows that the force between colliding cars is substantially the same, whether the struck car be standing alone or at the head of a draft of cars, as in classification yards. Furthermore, it shows that the force of impact does not extend throughout the sills from end to end, in a horizontal line, but that it is di- vided into many components, the average of which must be directed toward the cen- ter of gravity of the entire mass, and that it gradually decreases in magnitude, due to the fact that each increment of the load re- sists the force in proportion to its own inertia. As a further demonstration of this, a run was made with a test gear in car B only. At an impact speed of 1.98 M.P.H. the gear closed l 1 /^ in. All of the wheels of the standing car (car B) were then blocked, and the run repeated, car A being released from the same station. In this run the impact speed was 2.02 M.P.H. and the draft gear closed 1^- in., or just g 1 ^ in. more than in the preceding run when car B was free to move off. In the second run the wheels of car B slid 1% in. along the track. A point of some interest is with respect to the position of the gears in the cars; whether the gear in the striking car or the standing car tends to close first. A number of double gear runs were made, changing the gears from one car to the other. A number of single gear runs were also made, using a test gear in car B, with the solid buffer in car A, and then placing the same gear in car A and applying the solid buffer to car B. No difference in gear action occurred from these manipulations, and the tests showed conclusively that the loca- tion of the gear, whether in car A or car B, is immaterial. When but one of the two cars is equip- ped with a gear the action is restricted to that gear, and laboratory tests are more nearly reproduced. Throughout the tests the gears used in car B for the single gear runs had been previously tested in the laboratory, and a direct comparison of in- dividual gear action in service and labora- tory operation can thus be made by means of the single gear runs. The time-closure curves show generally that when but one car is equipped with a gear the line of actual gear action corresponds closely with the derived line of gear action (lines B and C, time-closure curves). In the double gear runs, however, where two gears are working in opposition, and one or both of them may operate or stick, it will be seen that almost invariably the closure takes place by a succession of alternating move- ments between the two gears. Another point of interest in comparing these two classes of runs is in connection with the gear capacities, or, in other words, the closing speed when using one gear of the type or using two gears of the type. The table, Fig. 65, has been prepared to show the relative performance of the single gears and double gears of each type. In this table Column 3 gives the actual closing speed when using the two test gears. Col- umn 4 shows the calculated impact speed Draft Gear Tests of the U. S. Railroad Administration 121 MAKE AND TYPE or GEAR % COMBMD DROP TESF WU/EOF T7/ES£TW0 TESFGFAK COMBINEO DROP TEST VALUE OF TWO AVERAGE COAfAfER- CIALGEARS ACTUAL CLOSING SPEED W/TH TWO TEST GEARS M.R. H. CLOSIA/6 SPEED WITH TWO AVERAGE COMMERCIAL SEARS A4. R. H. W (3 © (£ (?) @ WE5T/A/GH U5E D-3 O CAR 4AO " 39.6" 3.65 3.59 s CAR WEST/N6H0U5E NA~/ 7 C/ B R 5/.0 " 52.0 ' 4.16 4.24 QCAR SESS/ON5 A //**" 38./ " 37.6 " 4.37 4.33 /£<%" SESSIONS i/UMSO f4°a R 56./ " 56.2 " 4.30 4.22 IS™ CAPDWELL G-25-A /7«iT 4/. 5 ' 37.8 " 4.05 3.66 /A CAR /O x\ CARDWELL G-/8-A 20%* 36.5 " 39.2 " 3.85 3.89 2I CA » M/NER A-/Q-S 23 c %" 42./ " 39.6 " 4.46 4.33 24 C T M/A/ER A-2S 26 c %* 26.0 " 25.4 " 3.2/ 3.26 21 C * R NAT/ ON A L 29%" 62.0 " 62.4 " 5.07 5.09 30 c £" NATIONAL M-/ 32 c %* 39. / " 38.4 " 4.26 4.22 33 C T NATIONAL M~4 35*%* 45.0 43.0 " 4J2 4.03 36 c «" MURRAY H-25 38 c %" 33.3 34.0 " 3.45 3.52 39 c ** GOULD /7S jjCAR 35.9 " 36.2 " 3.56 3.59 42 C * R BRADFORD A- 45 CAR 20.9 ' 2/.6 ' 2.78 2.67 47°*? WAUGH PLATE 49 car 28.5 ' 27.8 " 3.02 2.98 so c Z" CHR/STY S2 C %" ^ryt «• 39.2 " 3.73 3.50 53 c £" fr*f-.0 HARVEY 2'Q"x8"8PGS. 55 C £ R 20.6 " /9.0 2.33 2.27 S6 c r CO/L SPR/NGS Z-&erCLASS G 5Q CA g //.4 //.6 ' /.S4 /.S7 59 c «r Note*- The above speeds are* for two cor5 y each of /43 t OOO Lbs. total ' we/'gfit Fig. 61 — Tabulation of Closing Speeds of Gears: Car-Impact Tests 122 Draft Gear Tests of the U. S. Railroad Administration S77/syVP0J. 03JJ/W -S-/VV&J. 33VOJ §UV3£>J.JVyO 12 A 9 myn-isy a £>±/j/v3 A 3/V3/D/333 NO/J.GV ~Z> AG 3NOO >/yOM IT. C139V05QV S-3/OOQ hlVD 2T A3 039&099\A\ ■3Qvys SB7 'J. 3 37jadoo &Aiiyna SS07AD&3H3 ^ U % 5 ^ J_DVdhfllV &3H3NI —31dAo ■£>'G BNIiJnOShlVDJO 370ADQ-0 30 7VJLOJ. J.JV&O 30 JA//70WV ^/O J.NIOc/ WO&3 03 HdM90M/3£ kO(V 5-» v yv3 h I* c*K75> ^o 3JAJ. I A & *o K s s V-. c\i ^ Q S-&V39 30 A0/J tfS>/J/SS b" 73 ^^ B X ** M M ^J s*? § ^ ^ M $ <* &$ JSL N § Q-<0 'Wcrh/P- OJ. 'HcTIa/P ^> .Kj ^ JNi. as 1 B "5^ & M CO »0 rvi «vi J7OA0'3'O JO -7VJ.OJ. ® vp cM, CO r CO CO, vO O tjv »M. 39V373& (§) 00 VO (VI CO O 00 10 Csi ? rO CM CO mSMAKD ® cvl vO r- o. vn V© O. (O 5 CVI CO (n O. #0 idV3£>JLJVXO JO J/MOWV * 5 > "to = o «M h @ = o 06 "0 CD «5 "lO "tf> "CO CO 9f>N/0Viy gm (S>) iO CO to 10. vO IV* to to WW3t 1WSIX S< © 10 \0 CO. • O O • CM CM, IVJ cv v» •5Q (Q CO £ VO CO tv. VD vO # k^ IM, ® < cJ M> V0 vn vO q 0: 5 CVJ CO ^ »0 f0 (vj 04 CO CO f0 tO VD en JO 3dAJL ® vl I> 1 Q §* & <0 ^vj 1 SI ft 1 S&V3S> JO VO/JV2W/S>£>V7D Q &3AO O/VV Wc/WJ* Ol W&Wp- < W O w fa3 ^-* H vS O Draft Gear Tests of the U. S. Railroad Administration 125 1^ i CM 2? CVJ 5 (SI rt 00 •VI VO vn o VO »o 8 *o vo *o o 3 5 O c- »o o 00 3 »o CO 05 0} «0 to "? cr» «o* CO ^CO VO • 01 10. ro o o M co to. m CO en. CVI in vO •o M CO o o 00 !2 C- (VI. c^ cvl «VJ s •* *. r- 0. •? (VI CO 00 X »o 52 r- cv| s vfi fO vO J o o 2 £ \£ s o 5 0> fsl *v£ s r4 £ "") in s rvi - 1 fO = S "(fO s. o s co S *vJ »0* ^CO VD "CO s co c6 "o r fO r vb CO' CO CM V£ £ N. i£J £ o CO «o |VJ # s CO • vO • 10 O ro t> 00 ur> «n s. 1- ivl. vO V0 o o cv« f. 00 vD »0 % CO 0D vf> s &. CO CO fO GO CO £ Jo cv* % 5: vD CVJ vO o \0 • O CVJ <« VX) 0\ 00 vD o p I CM S o vO O o CM c~ M ^ CO en CvJ vO CVJ vO »o «0 s? X N <& CO (0 o VO »o en X r I 5 CD p i 1^ 3fcS 1 1 ^3 8* -/-/■dWP OJL 7/c/WP '/Vcy^vT NWJ.S&37 < i— i L «i 126 Draft Gear Tests of the U. S. Railroad Administration S-rr/ShfV^OJL O 3 Jill* -SNb'&J- JOhfOj M CM o P f0 r- r- CM vp 10 AOM3/3/333 A/O/J.&yOS'&V w CO CO CD CD CO 00 «N* CO y\r'3£>J.3VyO A9 3/VOO »i/0M R m 1* f ^ 8 N in -sy-7 'J. j &V3QJ3VdO A9 03»ynl3H A £>U3N3 ® CO »*> rn 1 to CO IT) S VO <0 (9 £ VO 30NV1S/S3& 30\/bt£> 4 2j 3; vD ro in S&7 U3 J7JA0 9'0 9MtjnO S907A9&3A/3 O ro ^4 ^ S M CM % Or ^00 ® O O O £ a 00 ?3 0^ Si VD 8 00 p IM SO 5? 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N cvi % CM — rn O c— «o vO 00 N VO t en *f «o N * r- c- m CM CM CM CM oi CM M CM — — t O O O O s - = o = o X = co =— = iT> = «o "vD = o = o "5 vO JM "i£ JO "cm CM — en — "ob "■* 3 «o *vO "vb E = eo To = v0 "-vV "tn CO r 1 = «M > (0 _ r- - t- N »n to * (M fO — M — CM — m — — — -i * C- CM VO _ CO o m fO * •M »o — - ~~ — — CO 00 et o vO r4 1-7 ra vO VO -*- CVl t N, vn en c^- cn VO £ |S vO S S CM «M CM (Si CM ro CV4 CM O r— 04 CO CM VO vD iO 00 CM ^ f0 ^) CM f « ") »o X X X X X X X >< X X X ft lb (5 ^ gy r 5* 1 3Q ! f ' 5S< to® 4 Jrvj 7V -cr/v -fr oj. y&wr A/yW? W\/H±£S71 o p ^ 128 Draft Gear Tests of the U. S. Railroad Administration at which the single gear in car B should have closed, provided it functioned exactly as in the double gear run, the test gear having been removed from car A. This expected closing speed is based upon the relative work done by the two gears in the double gear runs, the work done by the two car structures being constant. Column 5 gives for comparison the actual speed re- quired to close the single test gear in car B. PIT Hi life B8j ^re^cs West/nghouseL P-3 CAR 3 %* 3.65 2.86 2.68 Wesmnshouse A/A-/ 7 CAR 8 C & R 4J6 3.24 3.06 Sess/o/vs K 1/ 1/2 <% R 4.37 3.62 3.8/ Sess/oass Jumbo 14 C § R WW? 4.30 3J8 3.26 Cardwell S-2S-A W car 'd C 1 R 4.05 2.9/ 297 Cardwell 6-/8-A WW v CAR A 3.85 260 2.79 M/NER A-/8S 23 c i CAR 24 CAR 4.46 3.74 3.57 A1/NER A-2S 2G CAR zft 27 '<%* 3.2/ 2.62 247 Nat/on a l 29 c % CAR $0 C £ R 5.07 318 3.95 Nat/on a l A4-/ \32 c i R W^¥ 4.26 3.36 3.08 Nat/onal M-4 35% CAR 4/2 3.24 3.33 Murray /i-28 38 c i' CAR 39 C 4 R 3.45 259 2.76 Gould /75 356 263 2.72 Bradford 46 K W c i R 2.78 2.28 2.04 Waugh Plate: 3.02 2.23 /S4 Crrasty 3.73 3.37 3.56 Harvey 2-8'k8"spRGs. 55 c § CAR rSPRGS.56^ R Srr/a/gs 58 c j R 233 /.64 /37 O/L 2-8x8°clas$g /84 /3/- /.45 Fig. 65 — Comparison of Double Gear and Single Gear Action. Car-Impact Tests. 143,000-lb. Cars. COMPARISON OF THE DIFFERENT METHODS OF TESTING A study of the performance of the in- dividual gears throughout the several dif- ferent tests can be best made from the tables of Figs. 17 and 66. In most gears a wide difference appears between the static test results and the dynamic results, but in general there is not a wide difference be- tween the drop test results and those in the car-impact tests. Static tests in general are usually made to determine the ultimate re- sistance of the gear, and the work done and work absorbed. It has generally been supposed that the character of the com- pression line was indicated by the static tests. These present tests show that the static test is not a measure, either absolute or comparative, of work done, work ab- sorbed or ultimate resistance. For example, in the static test the Westinghouse D-3 gears averaged 18,550 ft. lb. of work done, while in the drop test the average work done was 15,375 ft. lb., the static capacity being 12 per cent higher than the drop capacity. On the other hand, in the Na- tional M-l gear the static result is 263 per cent higher than that of the drop test. No uniformity whatsoever obtains in this per- centage. An interesting example of static test- ing is in the case of two of the National H-l gears tested after three years' service on the Norfolk & Western Railroad. These two particular gears were first tested in the static machine and showed an ultimate re- sistance of 296,000 lb. and 392,000 lb. respectively. The gears were then drop tested and the total fall of the 9,000 lb. weight required to close them was 17y 2 in. and 16y 2 in. respectively. The building-up test was then made under the 9,000 lb. drop and after an average of 21 blows per gear the total fall had increased to 29i/ 2 in - an( l 241/2 in. respectively. The gears were then retested in the static machine and showed an ultimate resistance of 112,000 lb. and 104,000 lb. respectively. All of these tests were made in a short period of time and under identical conditions. They show most clearly the erratic nature of the static tests. It is found in general, however, that the line of static compression follows the characteristics of the line of dynamic ac- tion, and that the ultimate resistance in the two tests are closely proportional to the work done in the tests. With some few exceptions, the drop test results, as to capacity and absorption, show a fairly uniform relationship to the car- impact results, the latter in general being from 5 per cent to 20 per cent higher than the drop test results. The drop test accord- ingly would appear to be a fair compara- tive measure of draft gears for capacity and absorption. The table, Fig. 66, shows the average capacity results from the gears in the different tests, the quantities being the average of those actually obtained for the two gears of- a type used in the car- impact tests. The following general conclusions are drawn from a comparison of the action of the gears throughout the different tests: 1. That the speed of static testing within the limits of the average testing machine has in general but little influence upon the ultimate resistance of the gear. 2. That gears of a type may vary great- ly in the static test and at the same time be of approximately equal capacity under the drop. 3. That the static capacity of a gear is no indication whatsoever of its dynamic capacity. — 129 130 Draft Gear Tests of the U. S. Railroad Administration 4. That in general, friction gears show greater capacity and higher ultimate re- sistance in the static test than in any other test. 5. That the ratio of ultimate resistance to work done varies but slightly as between different gears of the same type in the static test. 6. That the ultimate resistance in the static test and in the car-impact test is in general closely proportional to the work done by the gear in these two tests. 7. That the ultimate resistance in the car-impact test and the computed ultimate resistance in the drop test (Column 10, Fig. 17) are in reasonably close proportion to the relative amounts of work done by the gear in these two tests. 8. That in the majority of cases the static curve shows the characteristics of the dynamic action of the gear, but that it is not a true measure of its dynamic capacity or ultimate resistance. 9. That the drop test, with a single gear supported upon the solid anvil, is in gen- eral a fair comparative test of gears as to dynamic capacity. 10. That the car-impact results will in general be greater than the drop test re- sults by from 10 per cent to 20 per cent. 11. That the relative recoil of gears may be satisfactorily measured under the 9,000 lb. drop. 12. That neither the drop test, the static test, nor any other test using inelastic means for closing the gear will disclose roughness or irregularity of gear action: That tests upon a resilient body such as a standard car will alone disclose this fea- ture of gear action. The car-impact tests themselves have established and confirmed numerous prin- ciples of gear and car action, among which may be noted: 1. The relative merits of the different methods of draft gear testing. 2. The exact impact velocities at which the various gears will cease to offer further protection to the cars. •3. The production of complete dynamic cards of gear action. 4. The independent and inharmonious action of gears when dynamically closed in opposition to each other. 5. That gear action and car action in practice are not smooth and regular, even with the best friction gears. 6. That a friction gear is necessary for obtaining capacity and for eliminating recoil. 7. That the yield of the car structure and the lading do not afford any material aid in the dissipation of energy, and that fric- tion draft gears in modern cars are essen- tial to avoid high forces and early failure of parts. 8. That preliminary spring action shows no especial value in buffing and that heavy initial gear compression is not disadvanta- geous. 9. That the force developed between cars in buffing is due to the inertia of the cars, and when the slack is not bunched is the same whether the struck car be standing alone or whether it be at the head of a draft of cars; that the force is practically the same whether the struck car be standing with or without the brakes set. 10. That there is a positive displacement of the center sills relative to the side sills of a car, the amount of which is dependent upon the character of the construction tying these members together. 11. That in a modern steel car, a force equal to the ultimate resistance of the high- est capacity gear in these tests will be de- veloped between cars, without draft gears, at an impact velocity of iy 2 miles per hour. 12. That if a gear is properly con- structed as to sturdiness it requires but a slight over-solid speed to produce a high Draft Gear Tests of the U. S* Railroad Administration 131 *3a Average Work Done Per Gear. Ft LBs. average Work Absorbed Per Gear. Ft. Lbs. /n STAT/CC TEST i/v PROP TEST IN CAR IMPACT TEST in STATIC TEST /N DROR TEST /N CAR /MPACT TEST © © ® © ® ® © WEST/N6WUSL D-3 /8S50 /537S 74667 /6467 88.7% Z2533 8/6% Z2Z67 83.0% W6ST/N$WUS£ ZVA-Z /7250 79/67 Z47/2 85.4% Z67/7 37.2% Sess/ons 34700 Z4245 79367 32400 93.4% ///64 78.4% Z637S 84.5% UUMBO 47/35 2/773 79025 42725 90.GX /7460 80.3% Z43Z7 750% Cardwell 6-25-A 49550 /S563 Z79/7 475/7 36.0% Z3298 85.4% Z5554 86.6% Cardwell G-/8-A 26250 Z4453 777/7 25000 35.2% /3500 93.5% 75575 30.9% M/NER A-/8S 4/084 75769 787/7 584/7 93.5% Z2244 77.7% Z3334 7/3 X M/NER A-2S 54667 3762 70025 35/67 35.9% 6908 70.3 % 8477 83.8% Nat/onal H-/ 23250 27/84 Z3962 85.7% 20750 76.3% Nat/onal M-/ 53/00 74648 20000 50267 34.7% /2087 82.5% '76784 840% Nat/onal M-4 3/465 /6872 Z8467 29234 33.0% Z4337 85.0% Z58Z7 85.8" Murray H-2S Z8/34 Z2466 Z3900 /6250 89.6% /0002 80.3% ZZ584 83.3% Gould Z75 20/84 73478 73767 /70S0 84.6% 8/42 60.4% zozoo 73.5% Bradford K 6409 7830 6833 /708 26.7% 4340 55.5% 2Z50 3/4% Waugh Plate 8600 /03/3 9/00 44/7 5/4% 45/2 43.8% 4ZZ7 45.2% Chr/^sty 16684 Z2934 Z2623 75.7% Z09/S 84.4% Harvey 2-8x8"5fgs. 3034 7722 4992 4767 52.8% 4448 575% 2709 54.0% Co/lSfr/a/gs Wx8 CLASS G 3800 4279 4ZZ7 43.4 //4% a Z208 28.2% 450 ZO.9% Fig. 66 — Comparison of Work Done and Work Absorbed by Test Gears in Static, Drop and Car-Impact Tests 132 Draft Gear Tests of the U. S. Railroad Administration force peak; conversely, if a gear is not sturdily constructed an over-solid blow may never produce a high force peak, but such over-solid blows will quickly deterio- rate the gear, and so reduce its efficiency that low impact speeds will cause damage to the car.' 13. That the average period of draft gear compression with a friction draft gear is equal to approximately 1/3 of the entire cycle of impact and that the release occu- pies approximately 2/3 of the cycle. The maximum period of impact experienced was approximately y 2 second. 14. That with a spring draft gear the period of compression and of release are approximately equal and that the spring returns practically all of the energy, bring- ing the striking car to complete rest and imparting almost the original velocity of impact to the struck car. 15. That several acceptable draft gears are now available capable of protecting a 57i/2-ton car up to a switching speed of 4 M.P.H. Furthermore, that there is not an occasion for higher switching speeds than 4 M.P.H. General Deductions From the tests as a whole the following general deductions can now be made and are recommended by the Inspection and Test Section of the United States Railroad Administration: 1. That for use on any car a gear should be selected which will not go solid at less than 31/2 M.P.H. nor more than 4% M. P.H. when the weight of the particular car to which it is to be applied is con- sidered together with the complete informa- tion given in this report. 2. That there is no advantage in buffing from preliminary spring action, and that a draft gear should preferably be under some initial friction compression; not only for the increased capacity effected, but also to hold the friction elements in posi- tive engagement at all times, in order to provide a greater latitude of wear and to prevent the deposit of foreign material upon the friction surfaces. 3. That draft gears should have an effec- tive area for receiving over-solid blows slightly greater in extent than the area of the coupler shank; that this area should be presented in direct line with the force and should preferably be relieved of all other draft gear forces. 4. That all gear units should be of in- terchangeable dimensions and of equal travel. That considering the results of the high capacity Miner and National gears of 2y 2 in. travel, both in new condition and after prolonged service, together with the results from the Westinghouse NA-1 gear which is also of high capacity and of 3 in. travel, it is believed that the maximum travel figure of 2% in., as set by the Com- mittee on Standards of the United States Railroad Administration, might well be set as a fixed and required standard travel for all new gears. 5. That from this standpoint of satis- factory operation there is no reason why a draft gear of 2% in. travel should not be designed with an ultimate dynamic resist- ance of 500,000 lb., provided the rate of increase of resistance is uniform through- out the travel of the gear. 6. That no gear should be of a greater capacity at this travel than will close at an impact velocity of 5 M.P.H., with 57%- ton cars, or show a greater drop test ca- pacity than 25,000 ft. lb. Such a gear will close in a 120-ton car at 3% M.P.H. 7. That the expression, "a draft gear of 150,000 lb. capacity," is erroneous and should not be used ; and that the % in. rivet shearing test as used to define the above expression should be abandoned in favor Draft Gear Tests of the U. S. Railroad Administration 133 of regular 9,000 lb. drop tests, or prefer- tion, Section 3, should provide itself, with ably car-impact tests, until such time as a a gravity car testing plant of the general more convenient test for smoothness of character of that used for these tests, gear action can be developed. whereupon to conduct such draft gear and 8. That the American Railroad Associa- car construction tests as may be desired. RESULTS TO BE EXPECTED FROM COMMERCIAL GEARS The table, Fig. 67, has been prepared to show in condensed form the average re- sults that may be expected from new com- mercial gears of the different types. This tabulation embraces all of the different tests and the results in general are based upon the average performance of all of the gears of a type in the tests. This tabulation may be used as the basis for any comparisons desired of average gears. In Fig. 68 are shown energy curves for cars of different weights, the rotative en- ergy or fly-wheel effect of the wheels and axles, which amounts to an addition of ap- proximately 3 per cent, being included. Horizontal lines representing the closing points of the various gears have been lo- cated on this diagram so that the value of any gear upon cars of the different weights may be readily obtained. These horizontal lines for the several gears are based upon the action of the average commercial gear. By means of this diagram the application of the results may be readily converted from a specific case to general cases. In considering the cushioning value or closing speed of a gear it should be remem- bered that the kinetic energy of the striking car should be equal to approximately four times the energy required to close one draft gear. The present report contains much in- formation deduced from the car-impact tests relating to draft gear functioning such as, time of gear cycle, vibrations in car bodies, travel of cars along the track dur- ing the several portions of the gear cycle, instantaneous car velocities, transition and absorption of energy, forces developed, comparison of dynamic and static work dia- grams, car body absorption and other gear characteristics. This is given, in general, for the closing runs with the single gears and for the 1 M.P.H. runs and the closing runs with the double gears. A wide range of further draft gear information is ob- tainable from these tests, especially from the intermediate runs made upon each gear and particularly from those just slightly below the closing point. As a specific ex- ample of what may be done in this respect, the intermediate runs have been worked up for the Westinghouse D-3 gear and sum- mary curves have been developed. These are shown in Fig. 89, where can be seen for various impact velocities: (a) The velocities of the cars at parting. (b) The coefficient of restitution. (c) The energy absorption. (d) The absorption efficiency. (e) The track movement of the cars. (f) The force developed between the cars. (g) The time of the draft gear cycle. (h) The amount of gear closure. The same factors are also expressed in terms of gear closure instead of impact ve- locities in curves j to q inclusive of this same figure. Lack of time has prevented an analysis of all of the gears in this manner, as the immediate effort has been to present suffi- cient information for each of the several gears to properly compare and grade them. It is hoped to make further studies of an analytical character from these tests, the results to be published when completed. From such studies can be established and verified many of the fundamental laws of draft gears which are at present unde- veloped. From the present test data also such studies can be made as: the coeffi- 134 — Draft Gear Tests of the U. S. Railroad Administration 135 cient of friction under a wide range of con- ditions, such as various materials, unit pres- sures and relative velocities of one friction face upon the other; the effect of various spring and friction relationships; angu- larity of friction faces, etc. In short any further work should be the development of the intermediate runs, the production of summary curves, a study of the funda- mentals of gear construction, and the for- mulation therefrom of mathematical laws of draft gear action. 136 Draft Gear Tests of the U. S. Railroad Administration o ca, <1 S -8 C/3 co /V/ U/AS- SO S7T/S- ox bnoH H3d S31/N ^ HO/HM. IV &/7QH *3c/ 9J7W •ff^K? +OOOKW SUVJ-Q 2 9SOTQ 02 xnoH yj^ sj7w H SUSJ{ AOVdM/ MO ® Rx % $ ±DYdH/-#\r) s t: JOJQ O/AXLg ¥ » lDVJU//-d\/J © dOJQ D/2.yj.Q 8 $ J.S31 JLO\/dH/-dVJ 11 2/j.yj.S ® il 1 77^ 7K^C£ © 3U0JLSQ/0L a&7 y ti M eg N l<0 MF/? HOUR. Fig. 68 — Energy Curves for Cars of Various Weights, with Commercial Gear Capacities Indicated GRADING OF AVERAGE COMMERCIAL GEARS Any one familiar with draft gear oper- ation and testing can from the foregoing results, and particularly from table Fig. 66, establish his own rating of the gears. The relative total merits of the types will differ, depending upon the importance at- tached to the several features of gear ac- tion. No one gear excells in all points. One represents the highest capacity ; another the highest percentage of absorption; another the highest degree of smoothness of action. The tabulation, Fig. 69, has been pre- pared on the basis of the following rela- tive weights or percentages for the several phases of gear performance: Capacity 50 points Smoothness of action 15 points Closing pressure 5 points Absorption 15 points Over-solid sturdiness 10 points Workmanship and General operation 5 points Total 100 points The gradings on the above basis are made directly from the test results, except for the last item of 5 points which represents those features that it is impossible to de- note in abstract figures. Capacity In setting percentages as above, gear ca- pacity is unquestionably the prime meas- ure. A gear might excell in all other points and yet properly belong at the bot- tom of the list because of an extremely low closing speed. After a gear is closed it becomes a question of metal to metal for the remainder of the blow, hence the im- portance of continued gear action at higher impact velocities. The grading of the gears as to the capacity is based upon the square of the closing speed of the commercial gear. Smoothness of Action After capacity, the next feature is smoothness of gear and car action. With equal capacities, that gear is the best that will start off the struck car with the least disturbance and vibration of the car struc- ture and the least shifting of the lading. But it is not to be expected that a gear capable of cushioning the blow up to five miles per hour will ease off the cars at its high clos- ing speed like a 2 M.P.H. gear at its lower closing speed. The first gear is doing six times the work of the second gear and doing it in the same limited distance, hence more disturbance is to be expected with this gear at 5 M.P.H. than with the light gear at 2 M.P.H. The grading of the gears for smoothness of action is based upon the relative smoothness of the velocity curves in the closing runs, with the square of the actual impact velocity of the run introduced as a factor. Ultimate Force or Closing Pressure All other things, and particularly ca- pacity, being equal, the gear that puts the least force into the sills at the closing point of the gear is entitled to a credit. This is, however, largely allowed for in the pre- ceding grading of smoothness of gear ac- tion, inasmuch as the lower and more regu- lar force will produce the smoothest ve- locity curves. The closing force of a gear, furthermore, is largely governed by the amount of travel of the gear. But in order that those gears that have a dynamic card of decidedly full area may have credit, a weight of five points has been allowed in addition to the previous allowance of 15 points for smoothness of car action. The ratings for the several gears in this respect are not based directly upon the closing — 139 — 140 Draft Gear Tests of the U. S. Railroad Administration pressure of the gear, as it could not be ex- pected that a 5 M.P.H. gear should close at the same ultimate force as a 2 M.P.H. gear. The grading in this respect is based upon the ultimate force per foot pound of closing capacity. Absorption While energy absorption, contrary to a popular understanding, does not in any manner reduce or absorb the force between two colliding cars, it is of importance as indicating whether the force between the second and third cars will be the same, due to high recoil of the gears and rebound of the cars, or whether the energy of closure will be partly absorbed. These gradings are made on the basis of percentage of ab- sorption instead of absolute absorption, as a certain amount of recoil is necessary for parting of trains and to insure gear re- lease, the amount of which varies accord- ing to the capacities of the gears. A gear with too high a percentage of absorption is likely to stick, especially in train service. The higher the gear capacity the more foot- pounds of energy are needed to insure its release. Hence the percentage of absorp- tion is undoubtedly the fair basis of grad- ing in this respect. In allowing 15 points for absorption it has been borne in mind that the capacity grading alone takes care of absorption in a large measure, for high capacity is impossible except by means of friction, and the introduction of friction at once produces absorption. Hence any gear of high capacity has necessarily a high amount of absorption. Over-Solid Sturdiness It is highly important that gears be sturdy enough to withstand reasonable over-solid impacts. For a good showing in over- solid laboratory testing, it is desirable to have a weakly constructed gear, but for en- durance and life in service it is necessary to have sturdy parts to receive the solid blows. The grading in this report is based upon the number of over-solid blows re- quired to produce visible gear failure. Workmanship and General Operation Under the title of workmanship and gen- eral operation are included not only the finished and workmanlike manner in which the gears are constructed but those facts and impressions which have been gained during the progress of the test. Certain gears are finished articles throughout, well designed mechanically and exhibiting care- ful and accurate manufacturing practices. Other gears are carelessly produced and put together with apparently no thought as to the accurate relationship of the vari- ous parts. Some gears failed in certain de- tails before reaching the solid point in the test. Other gears stood extreme punishment without failure. Five points only have been allowed to cover this large variation be- tween the greatest and the least excellence, and it is conceded that this is not enough to represent these differences. The reason that five points only was chosen is be- cause this one item of workmanship and general operation is to a degree a matter of opinion on the part of the testing en- gineer, and the element of personal opin- ion is thereby reduced to a minimum. Service Performance of Gears It is recognized that the service perform- ance of the gears is one of the most im- portant considerations, but in the absence of positive and uniform service tests for all gears no grading has been made in this respect. Some notes on service tests and service testing appear hereafter. State of Development of Gears It is recognized also that those gears are entitled to credit which have been under de- velopment and in use for a longer period of time. This factor cannot be reduced to abstract figures, but can be best judged by the history of any particular type of gear on the specific railroad. Draft Gear Tests of the U. S. Railroad Administration 141 2 O 5 S MAKE ANO TYPE OF GEAR. £5 ie O m 111 " *' 00 " < a? «i ec r r tf z * - IS TOTAL © © © © © © © © -5 > 'UE National HI 50 7 3 12 10 5 87 X a: N ■ofi < E WCSTlN6H0V*f NA-I 36 15 4 15 3 5 78 Miner A-18-5 38 8 3 13 6 5 73 Nat/onal Ml 36 9 3 13 7 5 73 NATIONAL M4 35 8 5 14 5 5 72 SESSIONS J UMBO 36 9 4 13 3 4 69 Sessions K 38 2 4 13 1 2 60 * a.- CAR DWELL 6-2S-A 30 II 4 15 2 3 65 CARDWELL G-I8-A 30 9 4 15 2 4 64 W£ST>M&H0VJ£ 25 II 4 14 3 5 62 MURRAY K-25 25 IO 4 14 3 4 60 MINER A- 2-5 21 IO 5 14 5 3 60 Gould 17,5 25 8 3 12 3 4 35 CHRISTY 24 5 4 14 6 1 54 d: M < < -i x w H UJ -1 WAUftH PLATE 18 IO 1 8 2 5 44 HARVEY 2-8"*8"5PRiNW 10 5 1 9 3 5 33 Bradford K 16 7 2 5 1 1 32 Coil SPRiw&j 2-ARA- CLASS G 7 4 3 2 2 5 23 (A word of caution is necessary in using this table. While in most cases the statement is made in the chapter on "Selection and Condition of Test Gears," page 24, that the results of the tests are believed to be representative of the action of the commercial product, certain exceptions are noted, namely: Cardwell G-25-A, Murray H-25, Bradford K and Christy. — Editor.) Fig. 69— Grading of Gears, Based Upon Performance of New Commercial Gears SERVICE TESTS It has not been possible during the per- iod of the present test work to begin the comprehensive series of service tests de- sired. It has been planned to equip not less than 20 cars with each type of gear in these tests and to run all of the cars in the same restricted service so that uniform treatment may be accorded each type of gear. The gears are to be inspected, meas- ured, and drop tested before application to the cars and are to be kept under con- tinual observation. Ten cars with each type of gear to have Farlow draft gear at- tachment and ten to have yoke and lug at- tachments. Five cars in turn with each type of attachment are to have the draft gear protected by allowing the coupler horn or the Farlow middle key to strike. The remaining five, with each type of at- tachments are to have the full load de- livered to the sills through the draft gear. The condition of the gears, attachments and cars is to be reported each year and all gears are to be removed for laboratory tests after two years of service. Those worthy of further testing are to be con- tinued in the test for an additional period of two years. It is only in such a careful and comprehensive test that reliable serv- ice information can be obtained. A similar service test embracing five types of gears has been under way on the Norfolk & Western Railway for approxi- mately four years. The United States Railroad Administration Inspection and Test Section was thereby afforded an op- portunity to observe the service action of test gears of several different types. In the Norfolk & Western tests the National H-l and Miner A-18 gears showed the least percentage of depreciation. Gears representative of the average condition of these two types, after three years of service on Norfolk & Western 100-ton coal cars in restricted tide-water-service and aver- aging at least 50 miles per day, were given car-impact tests by this Section. A num- ber of gears of each type in the Norfolk & Western test had been removed and tested under the 9,000 lb. drop. These had been carefully handled from the cars to. the testing machine and the closing point was determined in as few blows as pos- sible without disturbing the foreign ma- terial upon the friction surfaces. Two average gears of the National H-l and the Miner A-18 were also taken to the car- impact test plant at Rochester and tested in the same condition as to friction surfaces. The worn Miner gears closed at an impact speed of 3.48 M.P.H. and the National at 4.21 M.P.H. The capacity of the Na- tional gears averaged 21,000 ft. lb. and the Miner 14,200 ft. lb. The gear action and cushioning were good in both instances and the actual capacity of these gears and the protection being afforded the cars after such a period of service is unexpectedly high. The table, Fig. 37, shows the aver- age condition of the several gears in the Norfolk & Western tests, and shows by means of the drop test, what each type is actually doing in service. The table shows also, by means of the restoration test re- sults, what portion of the depreciation is probably due to wear and what to foreign material upon the friction surfaces. These service tests were made in a careful and exact manner and with uniform conditions for all gears. — 142 TRAIN-OPERATION TESTS It is desirable to make a series of train- operation tests of draft gears before fully determining upon ideal gear characteris- tics. But a complete mathematical an- alysis of the car-impact data contained in this report should be made before begin- ning such road tests. All of the necessary information is at hand in these present re- sults for the accurate calculation and de- termination of the ideal gear for train starting and handling as well as in yard service. After such analysis is made a rational program of train tests can then be formed for confirming the calculated results. This method will not only insure a test program directed straight to the ends sought but will also obviate many un- necessary tests that would otherwise be made in searching for the desired informa- tion. In connection with the Norfolk & Western service tests an opportunity was presented for obtaining some limited in- formation as to the action of draft gears in actual train service. In this test, adjoining cars were equipped with gears of differ- ent capacities and characteristics, and by means of chronographs, each gear was caused to draw a continuous line of gear action upon a moving ribbon of paper. The report of this test, dated November 4, 1918, is appended to the present draft gear report as a matter of general information and record. (See Appendix A.) TESTS OF DRAFT GEAR ATTACHMENTS While testing draft gears, the opportunity was presented for making car-impact tests of draft gear attachments. Two 70-ton United States Railroad Administration low side gondolas were equipped with Farlow two-key draft gear attachments and tested in comparison with United States Railroad Administration standard cast steel yoke and lug attachments. A full report of this test, together with tests of wood car construction with and without metal draft arms, is at- tached to this report as Appendix B. 10 143 — 144 Draft Gear Tests of the U. 5. Railroad Administration MAKE AMD TYPE OF GEAR Car-Movement Curves Velocity Curves Energy Curves Time - Force Curves Tir\AE- Closure Curves Force -Closure Curves Ui*S ui a . (E 5 a i Q — ^ j < 2 ? go* p - J T 2 J)lil j; 2 d 5S1 ' Q a u u b c d € •r 9 h j k J m Tl P /j figure 7in .05 -o/V-/Sec. Gear JO V5 . * ,, n Sec Gear- /?e/ease^ .20 .25 .30- 35 .40 .45 ^^'Compre - 0/ ji Sec. Drcrfj- Gear Cyc/e^ lesf Gear No. 30 in Car A lesf Gear No. 29 in Car 3 impacf Veiocifv — i.20 M.PH .0 5 ./( 1 ./, 5 .2 .2 5 .a .35 .40 .45 0.092 Compress/on Sec. Gear Re/ease. Q26Q OJS8 Sec. Draff- Gear Cycle 7 6 5 lesf Gear No. 30 in Car A lesf Gear No. 29 in Car 3 impacf Veiocifv — S.Q7 M.RH D /' 3 2 _ a f B jf yV ^r 1 P* s- Figure O ^osi£^ t 5 Sear ./O .15 .2 m *,r* Sec. Gear- / J25 .30 .35 .^O .45 Release. 'ss/on. C 3 f^ Sec. Ore ft Gear Wme — Seconds Curve D, determined from superimposed car-movement curves, represents combined draft gear movement and yield of car bodies. Curve C, obtained by eliminating car body yield from curve D, represents true combined movement of both gears. Curve B, traced on small drum, represents movement of gear in Car B. Curve A, derived from curves C and B, represents simul- taneous movement of gear in Car A. Figs. 71n and 71q— Time-Closure Curves, National H-l Gears Draft Gear Tests of the U. 5. Railroad Administration 151 600 1 260- 5o//of Buffer In Car A. 500 Test Gear Na r 29 tn Car B, Impact 'e/oc/ty=3.95 / tPH 420,000 » 400 300 % *o "ft Wi r ^ '/ 'ygure I 7/r £ < i / 1 > 3 I Gear C/osure —/nct?es 9VL 1 2.46 — Test Gear /Vo. 30 //? Car A. 80& Test Gear No. 29 /n Car 3. ! f/r?pact\ Ve/oc/ty=5.07 MPH. \ 700 60& Gear C S50.0L Jasecf i ?0*~~~A 500 1 (7< Test- Sear Ad.// in Car 3 C/c s/ng Sp 6 >ed Car B — 2.64 W/?M sS*/./2M./?H. i r 2 r C3 1 hjr >3 J! c$S (0 b * A O (3 5 | S 1 f < vl 5 /,,,.,— -*"^! i i figure 7ea d OS 5"«>c 6isw ^ Sec. Gear^ Re/ease. 20 25 30 .35 .-40 .45 4 Compression. a£> •c. DrcrPf Geo/" C\yc/e. Fig. 72a — Car-Movement Curves, Superimposed. Sessions K Gears. These Curves Drawn by Cars in Test Draft Gear Tests of the U. S. Railroad Administration 153 TTme — Seconds. r u I Te^y- Gear No./2/n Car A Tes-r Gear No.// tn CarB ao sing Spe ed Can e £9SAt.PH. — Car A l/o s./.t/rrsrn 1 I 1/ (£r | § /^ I •' 5 • .5 -M-A 1 1 f, < D 5 3 1 1 r n u 5 1 f figure 72c Jt OS JO JS 20 .25 • OOSS ^ ec G* ar ' i L -» — ■ "SSec- Gear- ffe/ease. 30 .35 .y **'"" s „'' 7 ' 'SVi! Jjjj 'i ^ /j Ft per sec. 'I I l/l ! l/l I ' / I I TfWlA •/ If i 1 1 I X ! ! ' V L' -/.36 Ft per sec. fTgure 72f Sec ^7«7/- Compress/on *? ./! ? 2 5 30 .35 40 46 7/me— Seconds Dotted lines represent instantaneous car velocities as de- termined from the original car-movement curves. The irregularities are due in general to vibrations of the- car structure induced by draft gear action. Full lines represent the mean velocity curves. Fics. 72d, 72e and 72f— Velocity Curves, Sessions K Gears 60 40 20 20 40 Draft Gear Tests of the U. S. Railroad Administration 155 FtLbs. Sdiicf Buffer in Car A Test Gear No. // ih Car 8 iirpacf Vehctj-y=3. 6/ MPH. -34.247 FtLbs -6J96 Ft. Lbs. ^30735 Ft Lbs. Work Absorbed figure 72g -~O.0G4 Sec. Sear Co/r, 0JS5 Sec Gear Re/east ?0$& Sec. Praft Gear Cyc/e— 25 30 35 40 45 Test Gear No. /2 /h Car A Test Gear No. // /n CarQ Anpact Velocity - — /JO M.RH. Test Gear No. /2 in Car A Test Gear No. // in CarB jhpacf Vetocfty — 437 M.RH. Time — Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Figs. 72g and 72j — Energy Curves, Sessions K Gears Dotted lines represent the energy stored and absorbed luring the draft gear cycle. 156 Draft Gear Tests of the U. S. Railroad Administration 700 So/to* Buffer fn Cor A n Test Gear No. // /nCor 8. t /mpoct Ve/oc/ty=3.d/ MP//. 600 500 400 WO figure 7ek *" .05 JC 7 ./£ .20 25 .30 35 40 4S 1 Sec. "Gear Cor — 0.2/8 repress. (Sec. Draff Gear Cyc/i 300 20C\ Test GeorNo. /2 /r? Cor A. Test GeorNo.// /ru 'est GeorNo./ I mpoct Ve/oc/, ?/i. too -0.075- ^05 JO ./5 .20 0./28 Sec. Gear Re/ease ■ 25 30 35 40 45 Sec. Gear Compress. — ■ 0.203 Sec Draft Sea, Cyc/e- 100 Test Gedr No. /2 /n Car A. Test GeorNo.// /r? Cor B. /mpoct Ve/oaty=437 MP//. 600 500 400 200 /oo figure 7em Sec. Gear Compress/on /0 .£ 5 20 25 .30 35 40 45 -0.282 Sec Draff Gee tr Cyc/e Figs. 72k and 72m— Time-Force Curves, Sessions K Gears Draft Gear Tests of the U. S. Railroad Administration 157 So/id Buffer in Car /I Jesf Sear No. // in Car B /mpac-r Ve/ocrry=3.6/MfiN. 45 % Tesr Sear No./2 in Car A les-r Sear No. // in CarB /mpac-r Veioci-fv = /./M. P.H. 1- j 1 figure 7ep ^ % .OS .n rrr- Sec Gear > JO IS 2i /,,» 5ec. Gear fie/ease. .25 JO 35 * .40 .45 k " ° 7 ° Compression "«*'*•« ■ O "'tfj < ^ ec Drtrfi- Gear Cyc/e 7 6 Test- Sear No./2 in Car A Test- Sear No. ii in CarB /mpac-r \/e/oafv=<4.31MPH. D Sec. DrarT+ Gear Cyc/e. 77me — Seconds Curve D, determined from superimposed car-movement curves, represents combined draft gear movement and yield of car bodies. Curve C, obtained by eliminating car body yield from curve D, represents true combined movement of both gears. Figs. 72n, 72p and 72q — Time-Closure Curves, Sessions K Gears Curve B, traced on small drum, represents movement of gear in Car B. Curve A, derived from curves C and B, represents simul- taneous movement of gear in Car A. 158 Draft Gear Tests of the U. S. Railroad Administration 700 -110 s — Sofia/ Buff er /r? Cor A. 600 Test Gear No // //? Cj?r3. impact, l/e/ocJty-33/ Mm SOO 400 325,000' ^ > ' 300 J y 200 figure 72r 6 / 2 c 6 ear C/osure — /nches 500\ X K400 300 200 /OO W. %sf~Gear Na72 //7 Car A. —Test-Gear-/Vo.-//-/r7-Car-3, I impact Ve/oc}fy=4.57AfP/i. Gear C/osure —Inches Figs. 72r and 72t — Force-Closure Diagrams Sessions K Gears Draft Gear Tests of the U. S. Railroad Administration 159 Softd Buffer in Carsl 7est Gear No. 23 in Car 3 17me — Seconds Fig. 73a— Car-Movement Curves, Superimposed. Miner A-18-S Gears These Curves Drawn by Cars in Test 11 160 Draft Gear Tests of the U. S. Railroad Administration 17me - — Seconds Figs. 73b and 73c— Car-Movement Curves, Superimposed. Miner A-18-S Gears These Curves Drawn by Cars in Test Draft Gear Tests of the U. S. Railroad Administration 161 ■ IS .20 Sec Gear Compression^ 0.207 Sec. Gear Release - : 0.09B ' —0305 Sec. Draft Gear Cycle— T/me^Seconds Dotted lines represent instantaneous car velocities as de- termined from the original car-movement curves. The irregularities are due in general to vibrations of the car structure induced by draft gear action. Full lines represent the mean velocity curves. Figs. 73d, 73e and 73f— Velocity Curves, Miner A-18-S Gears 162 Draft Gear Tests of the U. S. Railroad Administration 80 ^■62.773 Ft Lbs. So//a/ Suffer- /n Car A 7es-r Gear No23/n CarS /mpac-r Ve/oa'fy= 3. S1HPH. W Car A 40 ~-3/.d70 FtLbs. W CarB-^ g~V££92 » FtLbs eac h car FtLbs. "\ 20 i \ mm J2ff222 Ft Lbs. Work Absorbed figure 73g ^3/£3S FtTbs.-tYorA Done 40 .0 062Sec.6earC 0.2 5 ynp V7 JO /S 20+ — O./SS Sec Gear Re/ease — Sec Draft Gear Cyc/e — 2S 30 35 40 4S lesi- Gear No. 24 in Car A Tes-r Gear No. 23 /n CarS ///pact Ve/oci+Y — /OS M.P/i. Test Gear Ma 24//? CarA Test- Gear No. 23 in CarS /mpact Ve/oc/ty — 4.4G M.PH 7/me — Seconds Full lines represent the instantaneous kinetic energy of the Dotted lines represent the energy stored and absorbed moving cars. during the draft gear cycle. Figs. 73c and 73j — Energy Curves, Miner A-18-S Gears Draft Gear Tests of the U. S. Railroad Administration 163 ! Kit Sofia* Buffer /n Car A Test Gear No. 23 m Car B. (maact Ve/oc/tv=3.S7 M.PH. WO 300 400 300 200 AXf figure 73k 0062 — JO JS .20 .25 30 35 40 45 Sec Gear Comi — 0.2H ?/TSSS. 7 Sec. Pr ^Sec. Gear zrfrGear C Re/ease yc/e — 300 Test Gear No. *24 //? Car A Test Gear No. 23 in Cor 3. Impact Ve/oc/tv=/.Q5 MPtf. ZOO zoo 3„ vl<> 05 JO /£ 20 25 30 35 40 45 * Sec. Gear C t 0./73 v o/rfpress. Se Sec Draft Gi c. Gear Re/ease x>r Cyc/e — 9 ' ^WO Test Gear No 24 /n Car A. Test Gear No. 23 /n Car 3. Impact Ve/oc/tv=4.46 MP/t. §600 r J 1 200 I 100 V Figure 73m .05 / 5ec Ge S^3h :ompress ' L 1 -^0305 Se 5 2 0.207 Sec. c. Draft Ge .25 3C Gear /re/ease or Cyc/e m > 3i S 4( 7 .45 Fig. 73k and 73m— Time-Force Curves, Miner A-18-S Gears 164 Draft Gear Tests of the U. S. Railroad Administration s So/td Buffer in Car A Tesf Gear Nb.23in CarB ffrpac-f Vehcif\s-3.S7HPH. 4 o 3 *s £ ___^!^sw« B ei / figure 73n ■OS ./O J5 .20 „ ,,-r- Sec Gear- Re/ease. .25 .30 .35 .40 .45 •° CC ComprVs S ,on. ' WAJO „ M _ _ . ^ -y-, Sec. Draft Gear- Cycle. r 17me — Seconds Curve D, determined from superimposed car-movement curves, represents combined draft gear movement and yield of car bodies. Curve C, obtained by eliminating car body yield from Curve D, represents true combined movement of both gears. Curve B, traced on small drum, represents movement of gear in Car B. Curve A, derived from curves C and B, represents simul- taneous movement of gear in Car A. Figs. 73n, 73p and 73q — Time-Closure Curves, Miner A-18-S Gears Draft Gear Tests of the U. S. Railroad Administration 165 \-2.S4*-~ 300 Sof/of ka/Ter fn Car A Test Gear No. 23 //? (fir 3. 800 /mpact te/ociity=3.57 Af.P/z 700 600 500 300.000%^ 300 (q 200 3 / s J figure & 73r / 2 Gear C/osure — //?c/?es /oo Test G ear No. 24 n' Car A. 600 lest Gear No.^ 23 //? (fir B. Impact Vebc/fy=4.4 6 Mm SOO Geons C/osecf 400 390,1 WO* s 1* 200 h y, l k Test Gear No. 25^, Cor 2?--. — -"^ f ■ * j figure 73t 0/23 Gear C/osure —/nc/ies Figs. 73r and 73t— Force-Closure Diagrams Miner A-18-S Gears 166 Draft Gear Tests of the U. S. Railroad Administration to So//d Buffer /n Car A Tesf Gear A/a 7 in CarB TFme — Seco/7a J s Fig. 74a— Car-Movement Curves, Superimposed. Westinghouse NA-1 Gears. These Curves Drawn by Cars in Test Draft Gear Tests of the U. S. Railroad Administration 167 Test- Gear A/a 6 in Car A lesi- Gear No. 7 /n Car 3 | 1 i A/om/na/ /mpocf- Ve/oc/fy /M.PH. It** Ume Seconds Figs. 74b and 74c— Car-Movement Curves, Superimposed. Westinghouse NA-1 Gears These Curves Drawn by Cars in Test 168 Draft Gear Tests of the U. S. Railroad Administration 6 So/id duffer /r? Cor A. Test Gear No. 7/nCor BY /mpocf Ve/odtv=3.0$ MPH 5 KT— 3.07 Ft per sec. 3 !\ — — 2.23 Ft per sec. 2 A /7.24 Ft per sec. / 3 figure 744 .05 JO 75 .20 25 3V 35 40 *£> Sec. Gear Compress 270 Sec. Draft Time — Seconds Dotted lines represent instantaneous car velocities as de- termined from the original car-movement curves. The irregularities are due in general to vibrations of the car structure induced by draft gear action. Full lines represent the mean velocity curves. Figs. 74d, 74e and 74f — Velocity Curves, Westinghouse NA-1 Gears Draft Gear Tests of the U. S. Railroad Administration 169 60 4S935Fti Lbs. Solid Buffer* in Car A Test Gear No. 7 in CarB Imjoacr Vehdtv*~3.06MPH & ^ 44,22/JFt Work Done Lbs ^40.3/22 rtLbs. Work Absorbea! 1 figure 7S/ .05 JC ^n/C" 1 Sec. Gear » J5 .20 .25 30 ,->->->/ Sec Gear- Re/ease. .35 40 .4, 5 ^"■"' Compression. 335 ^ L Iro-rr Gear Cycle. TTme —Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed during the draft-gear cycle. Figs. 75g and 75j — Energy Curves, National M-l Gears Draft Gear Tests of the U. S. Railroad Administration 177 Solid duffer in Car A. Test Gear No. 32 in Car 3. impact Velocity =3.08 M.PH 45 -0.254 Sec. Draff Gear Cyc/e O fy)0t lest Gear No. 33 in Cor A. Test Gear No. 32 in Car B. Impact Velocity =1.06 MPti. I -0.092- 05 JO J5 .20 0/74 Sec. Gear Re/ease - 30 35 ■40 Sec Gear Compress. 0.266 Sec. Draff Gear Cyc/e - 600- ■45 50O 400 300 200 /00 Test Gear No. 33, in Cor A . Test Gear No. 32 in Car 3. • Impact Velocity =426 6d£tL Time -Seconals Figs. 75k and 75m — Time-Force Curves, National M-l Gears 178 Draft Gear Tests of the U. S. Railroad Administration s So//d Buffer ai Car A 7esf Gear No. 32//? CcrrB /mpacr Ve/oc/i-v=3.Q8M. RH. 4 D c^£ T* 22Sb^^ / figure 7Sn .05 jo /5 .20 2, - .-.. Gee. Gear- Re/ease. 5 30 35 40 <5 ' xA - Kl Compression — 025 j Sec Ora-ff Gear Cyc/e. , Test- Sear No. 33 fn Car A Jes-f Gear No. 32 /n CarB /mpacf Ve/oc/ty=*/.06 M.PH .05 /S 20 25 30 35 4V 45 Curve D, determined from superimposed car-movement curves, represents combined draft-gear movement and yield of car bodies. Curve C, obtained by eliminating car-body yield from curve D, represents true combined movement of both gears. 77me — Seconds Curve B, traced on small drum, represents movement of gear in Car B. Curve A, derived from curves C and B, represents simul- taneous movement of gear in Car A. Fics. 75n and 75q— Time-Closure Curves, National M-l Gears Draft Gear Tests of the U. S. Railroad Administration 179 4UU • __., \So//cf puffer |//7 Car A. 3/aooo* 300 Test Sear No. 32 /n £ar 3. Impact Ve/oafy=30$MPH 100 y ^ Figure 7Sr 700\ Gear C/o&ure — /nch&s 600 <0 soo I ^ 400 ^300 -2.6/ A Test Sear No. 33 //? Car A. lest Sear No. 32 //? CarB. 1 H / mpact l/e/oc/t/=426 MP/i. 2 Gear C/osure—/nct?es Figs. 75r and 75t— Force-Closure Diagrams, National Ml Gears 180 Draft Gear Tests of the U. S. Railroad Administration 77/ne — Seconds Fig. 76a — Car-Movement Curves, Superimposed. Sessions Jumbo Gears. These Curves Drawn by Cars in Test Draft Gear Tests of the U. S. Railroad Administration 181 TTme — Seconds Figs. 76b and 76c — Car-Movement Curves, Superimposed. Sessions Jumbo Gears These Curves Drawn by Cars 1 in Test 182 Draft Gear Tests of the U. S. Railroad Administration 77/77e—Seconc/s Dotted lines represent instantaneous car velocities as de- termined from the original car-movement curves. The irregularities are due in general to vibrations of the car structure induced by draft-gear action. Full lines represent the mean velocity curves. Figs. 76d, 76e and 76f— Velocity Curves, Sessions Jumbo Gears Draft Gear Tests of the U. S. Railroad Administration 183 Soiid Buffer in Car A Tesf Gear No.i4 in CarB impact VeiocJty= 326 M&H 80 60 9Q740FtL bs. Test Gear No. /S in Car A lest Gear Afo. /4 in CarB irrpacf Vefocitv — 430 M.RH. CarrV^ ' 20 ^^S .300 Ft Lbs. CarB^ *~5,030Ft L bs. \ V \ K figure 76/ 40 •^ Work ?FtLbs. Done. 35,660 Ft Lbs. Work Absorbed 1 .05 ./O Tj0/ -y Sbc Goar Compression J5 .20 .35 .30 .3 m /lo o^» Sec Gear Re/ease. 5 40 45 D347^ Sec. Draff- Gear Cyc/t. - —J Itme — Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed during the draft-gear cycle. Figs. 76g and 76j — Energy Curves, Sessions Jumbo Gears 184 Draft Gear Tests of the U. S. Railroad Administration 600 500 400 3C0 200 300r * 200- 7est Gear No. /S /n Car A. Test Gear No. /4 /r? Car 3. impact Ve/oc/tv±/.Q5 MPfi. iog- .05 -0.097- Cor, JO Sec Gear Compress/on .15 .20 -0./93 -Sec. Gear Pe/sase- .25 30 35 40 0290 Sec. Draff Gear Cyc/e- '700 45 £ Test Gear No. /S /n Cor A. Test Gear No. /4 /n Car 3 fmpact Ve/oc/ty=430 MPti. T/me —Seconals Figs. 76k and 76m— Time-Force Curves, Sessions Jumbo Gears Draft Gear Tests of the U. S. Railroad Administration 185 SoM Buffer in Car A Test Gear No. 14 in Car 3. impact Veiocity3.24HPH .45 0246 4 lest Gear A/a i.5 in Car A lest Gear A/a/4 in CarB /mpact Ve/ocitv=i.OS HPH. 2 / figure 86p .05 ./< .nno7 Sec - Gear ? JS .20 .25 . r>/o3 Stc- Gean Re lease. .30 .35 40 .45 -0.097 c lest Gear MxiS/n Car A lest Gear No./4 in CarB impact Ve/ocitv^AZOMPH. °y , J rt ^h' ' / jU ZL >f -*r "\- M 4 ""^^S^ r A N xS. figure 76a .05 ./O m Q/-*f ^ ec Gear Compress/on. 9 JS .20 .25 .30 .3 _ /•» ■*->£■ Sec. Gear Re/ease 5 .40 .45 • 0347 Sec ~ Dra "ft~ Gear Cyc/e. ITme — Seconds Curve D, determined from superimposed car-movement curves, represents combined draft-gear movement and yield of car bodies. Curve C, obtained by eliminating car-body yield from curve D, represents true combined movement of both gears. Curve B, traced on small drum, represents movement of gear in Car B. Curve A, derived from curves C and B, represents simul- taneous movement of gear in Car A. Figs. 76n, 76p and 76q— Time-Closure Curves, Sessions Jumbo Gears 186 Draft Gear Tests of the U. S. Railroad Administration 600 -2AS"— — So//cf Buffer //? Car A. 600 7est Gear No. f4 triCarB. /mpact Ve/oc/ty =3.2(± ->MP/i. 400 377,000* » 300 100 too Figure 76r i f » 1 J \ Gear C/osure — //ycfies 60C 3.00- 283- 1 1 7est Gear No. 15 /n Car A. £00 Test Gear No. /4 /n Ozr 3. > Impact Ve/oc/7y=4.3G M.PN. 300 t 200 GearC/osed U37000#-^ , 1 TesT bear Mo. f4 l^~2* Car 3 — r*-f too -->- ~^Z~%st Gear No: /S figure ^-*—~ Car A p^S-""^ let C ) / 1 > c \ (Gear C/osure —focfres Figs. 76r and 76t — Force-Closure Diacrams Sessions Jumbo Gears Draft Gear Tests of the U. S. Railroad Administration 187 TFme— Seconds Fig. 77a — Car-Movement Curves, Superimposed. National M-4 Gears These Curves Drawn by Cars in Test 188 Draft Gear Tests of the U. S. Railroad Administration &W (5 lesr Gear No.3G/n Car A lesi- Gear A/o.3S /n Car B 17me — Seconds Figs. 77b and 77c — Car-Movement Curves, Superimposed. National M-4 Gears These Curves Drawn by Cars in Test Draft Gear Tests of the U. S. Railroad Administration 189 5o//d Buffer //? Cor A. Tesf Gear No. 35 /r? Cor 3. im pact \/e/oc/ty=3S8 Mm as. JO ./£ .20 ' — 0.055 -4— 0./59 Sec. Gear Re/ease Sec. Sear Conipress. ■ 0.7/4 Sec Draff Gear Cyc/e 25 45 0.355 Sec Draft Gear Cyc/e 7/me —Seconds Dotted lines represent instantaneous car velocities as de- termined from the original car-movement curves. The irregularities are due in general to vibrations of the car structure induced by draft-gear action. Full lines represent the mean velocity curves. Figs. 77d, 77e and 77f — Velocity Curves, National M-4 Gears 190 Draft Gear Tests of the U. S. Railroad Administration So//d Buffer in Car A lesir Gear No.3Sin CarB /mpact Velocit y 336 MPH JO ./5T 20 Q--- Q Sec. G&ar /Pg/eose. 3$904rtLbs. Work Absorbed .30 figure 77g *o m lest Gear Ato. 36 in CarA Test Gear No. 35 in Car 3 Time — Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed during draft-gear cycle. Figs. 77g and 77j — Energy Curves, National M-4 Gears Draft Gear Tests of the U. S. Railroad Administration 191 600 500 400 300 5o//d Suffer in Car A. 200 /oo figure 77k ./O /5 .20 0./S9 Sec- Gear Re/ease Sec. Gear Cbmjpress. 0.214 Sec. Draft Gear C/c/e • .23 30 .35 40 45 I 300 200 /OO Test Gear No. 36 /a Cor A. Test Gear No. 35 in Cor B. Impact Ve/ocNv=/.06MPft .05 -0.035- ./0 ./5 .20 .25 -0/82 Sec. Gear Re/ease Sec Gear Compress. 0.275 Sec. Draff Gear Cyc/e- 30 35 40 45 i' M Test Gear No. 36 h Cor A. 600 500 300 figure 77h? ? JO Compression J5 20 25 30 3i J 4( 45 — 0.35B Sec Drot 7 Gear Cy cJe T/me —Seconds Figs. 77k and 77m — Time-Force Curves, National M-4 Gears 13 192 Draft Gear Tests of the. (J. S. Railroad Administration i 7es"f Gear No. 36 Ai Car A lesi- Gear No. 35 /n CarB firpocf Ve/ocitv =/.0S M.RH. .0 5 /< ? A 5 a A 5 .3 .35 .40 45 7esi- Gear No. 36 /n CarA 7esi- Gear No. 3*5 in Car 3 fotpaef Ve/oc/i-Y = 4./2 M.&H. ^D^ y C "*^^ / - /y^\^ B \ _ r* Y fc *" V M- / > x: ^ ^ lr_ \ V^-~— LX figure 77q .05 /O *ni!/ Sec Gear Compression. J5 .20 .25 30 .3. m ~ ->s,* Sec. Gear- r?e/eaee. 5" 4 45 0.355-^ Drafr Gt Bar Cyc/e. If me — Seconds Curve D, determined from superimposed car-movement curves, represents combined draft gear movement and yield of car bodies. Curve C, obtained by eliminating car body yield from curve D, represents true combined movement of both gears. small drum, represents movement of Curve B, traced gear in Car B. Curve A, derived from curves C and B, represents simul- taneous movement of gear in Car A. Figs. 77n and 77q— Time-Closure Curves, National M-4 Gears Draft Gear Tests of the U. S. Railroad Administration 193 70C So// of {Buffer /n QarA. , 60C Test (Bear No. 35 /n Car @. /mpoct Vq/oc yfy=3 Q8M.&H SOC (A400 362.00$ Nl 1 ^00 J 40 200 ! <0 /oo 5 s F/gure £ — ** 77r 1^500 / 2 Sear C/osure — /nc/ies i j 2SS- 1 ! — 242" ! ^ G /est Gear No. 136//7 C lest Ge^^ Mn s^jn^y arA. or 3 400 Impact Ve/oaty=4/Z MP//. i 300 1 i i I 200 >ar-/Vch4, l~f(s$Q %*Z CarB~* f*a& \gr* /OO -== Pc %st Geo Zar-A— rNo.36 V { i i * figure lit ' Gear C/osure— /ncties Figs. 77r and 77t — Force-Closure Diagrams National M-4 Gears 194 Draft Gear Tests of the U. S. Railroad Administration /a So/id Buffer /n Car A lest Gear No.20 in Car 3 ■ /o C/os/ny tyeed CarB /.0SAt/?A /^^^ ^< Car A ^~Q83M.f?H. c^ J » ^V 1 ,0 1 \ <*> yi c5 .5 1 1 ° 1 1 3 <*> t 11 figure 16a w ¥ .05 ./C .^ mi Sec. Gear Compress^ ./£ 0.23t On .20 .25 SO _, Sec Gear Re/ease. .35 .40 .45 - O.c ?37~ Sec Tff Gear Cyc/e. Time — Seconds Figs. 78a and 78b— Car-Movement Curves, Superimposed. Cardwell G-18-A Gears These Curves Drawn by Cars in Test Draft Gear Tests of the U. S. Railroad Administration 195 "Time — Seconds Fig. 78c — Car-Movement Curves, Superimposed. Cardwell G-18-A Gears These Curves Drawn by Cars in Test 196 Draft Gear Tests of the U. S. Railroad Administration .05 JO /5 20 .25 30 ■O.J44 Sec. Gear Compress. — -J— *— - — 0.358 Sec. Gear /?e/ea~se -0.502 Sec. Draft Gear Cyc/e- 7?me— Seconds Dotted lines represent instantaneous car velocities as de- termined from the original car-movement curves. The irregularities are due in general to vibrations of the car structure induced by draft gear action. Full lines represent the mean velocity curves. Figs. 78d, 78e and 78f — Velocity Curves, Cardwell G-18-A Gears Draft Gear Tests of the U. S. Railroad Administration 197 So/a? BufTer /h Cor A TesTs Gear Ato.eo /n CarB Jhn pocT Vetoc/iy 2.7SMS?H. 9.4/9 Ft Lbs -/6.484 Ft Lbs -3.36/ Ft Lbs. 13.479 Ft Lbs ^Wor/r Done Worn Absorbea 78.472 Ft Lbs. figure 78g .05 -0/0/ -See Gear Comp. /5 -0.236 20 .25 •Sec Gear Re/ease- 30 35 40 45 0.337 Sec Draft Gear Cyc/e- too 7esi~ Gear No. 2/ Jh CarA Tesi- Gear Ato. SO ki CarB Jtopact Ve/ocrtv — 385 M.&H. ^72)930 Fi L Lbs ^-Car A - 3C 1 SOS Ft Lbs ^ 30 Car 3± , J ^IJ850Fi 'Lbs «s 46 Ft Lbs. — ' 20 ""< \ ^ ---< 31.230 FtL WorA Don*. bs ~ wm M M mi M M . ^^m SS.476FtLbs. HbrA Absorbed. -^, 05 ./O » nuist Sec. Gear Compression. '5 .20 2* 5- *0 .40 45 n & 35Q Sec Goar ' G&SBB^ fa ~U/44 r~ °* - . , c ' - I Time *- Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed during the draft gear cycle. Figs. 78c and 78j — Energy Curves, Cardwell G-18-A Gears 198 Draft Gear Tests of the U. S. Railroad Administration 600 Soi/d Buffer //? Cor A. Test Gear No. 20 in Car 3. impact [/eiocitv=2.73MP/f. 300 1 400 300 100 /GO figure 78k .05 ./C 0/0/ Sec. Gear Compress » /5 2< ~ 0.236 Sec. Gea, .25 30 .35 40 .45 300 200 & /OO O .05 ./O -0.//9Sec. Gear Compress: ./3 .20 .25 .30 -0.280 Sec. Gear Re/ease — .35 43 -0.399 Sec. Draff Gear Cyc/e- >600 \ Test Gear No. 2/ in Car A. Test Geor No. 20 in Cor 3. impact l/eiocitv=3.85MPH 700 600 SOO 400 300 200 /OO figure 76m ' 05 /O /. -0./44 Sec. Gear Compression -+• 5 20 25 .30 .35 45 .50 - 0.358 -Sec. Gear f?e/eose * » 0.502 Sec. Draft Geor Cyc/e — m Time —Seconds Figs. 78k and 78m — Time-Force Curves, Cardwell G-18-A Gears Draft Gear Tests of the U. S. Railroad Administration 199 6 So/id Buffer- /n Car A Test Gear No. 20 tn Car 3 /mpac-r Ve/oci-fv—273 M.RH. c^r ■ O 2 JT^ B Figure 76n .OS A ^nj^/Seo Gear* Comaress. ? ./S .20 .25 .30 /i? v Sec. Gear fte/ea&e. .35 .40 45 -0.3^ ~>-j Sec Dt-o ■f? Gear Cyc/e- Test- Gear No. 2/ in Car/1 Test Gear No. 20 /n Car 3 /mpacf Ve/oa+v=f.09 M.RH 3 / & 5" .k 7 A S 2 o .2 S 3 .35 40 .45 TesT Gear No. 2/ /n Car A lesi- Gear No. 20 /h Car 3 hpocf \Ze/ocity=3.6S M.RH 7T/7?e — Seconds Curve D, determined from superimposed car-movement curves, represents combined draft gear movement and yield of car bodies. Curve C, obtained by eliminating car body yield from curve D, represents true combined movement of both gears. Curve B, traced on small drum, represents movement of gear in Car B. Curve A, derived from curves C and taneous movement of gear in Car A. represents sinu Fics. 78n and 78q— Time-Closure Curves, Cardwell G-18-A Gears 200 Draft Gear Tests of the U. S. Railroad Administration 500 So/id Buffer /n Ca rA. Test Gear A/q. 20 //? CorB. /mpocr Ve/oc fty=ZJ9AtPH. ** ynn 255,000** i Nj 200 1 \ ^^*t >J /OO ( — =- Gear C/osure —/nches Figs. 78r and 78t — Force-Closure Diagrams Cardwell G-18-A Gears Draft Gear Tests of the U. S. Railroad Administration 201 Test Gear No. /6 in Cor A lest Gear M>. il in Car 3 C/osing Speed Ifrno — 9/ooono(9 Fig. 79a — Car-Movement Curves, Superimposed. Cardwell G-25-A These Curves Drawn by Cars in Tests 202 Draft Gear Tests of the U. S. Railroad Administration 1^ Test Gear No./6/n Car A Test Gear A/o./7/nCarB A/o/nina/ Impact Vetoc/ty 1 M.PH 0.203 Time-Seconds Curve S/ctended to Comp/eje Draft Gear Cyc/e Beyond Range of Recording Device Test Gear No. /d tn Car A Test Gear A/o./T m CarB C/os/ng Speed CarB figure 79c Time —Seconds Figs. 79b and 79c — Car-Movement Curves, Superimposed. Cardwell G-25-A Gears These Curves Drawn by Cars in Tests Draft Gear Tests of the U. S. Railroad Administration 203 Test Gear No. 18 in Car A Test Gear No. 17 in Cor B. impact Velocity =032 M.PH I: i -1.34 Ft. per sec. §53 Ft. per sec •^-.867 Ft per sec. 2/-.3G9 Ft per sec. figure 79e 10 .15 Sec. Gear Release 0.131 0. 203 Sec Draft Gear Cycler- mi 5939 * t per Sec. Test Gear No. 18 in Car A. Test Gear No. IT in Car B. Impact Veloci ty-4.05 M PH W^%L ± '"*\ \ S\. J-w A '-Car A /» V "VA^ ^■ f - "'Vy- ■^ v " "V» ' »' ^3 92. F t per sec r\3 i 1 * St 2 ** ^Cara^" Ft. per sec. 0V X i • e — 1.19 Ft}. 76 r aac s**&"^ fS*^ figure 73-T Sec Gear C § 10 fP/Tjpre&s/o'n IS .20 25 30 3S 40 4-5 ■> 0.396 Sec : Draft Gear Cycle Dotted lines represent instantaneous car velocities as de- termined from the original car-movement curves. The irregularities are due in general to vibrations of the car structures induced by draft gear action. Full lines represent the mean velocity curves. Figs. 79d, 79e and 79f — Velocity Curves, Cardwell G-25-A Gears 204 Draft Gear Tests of the U. S. Railroad Administration €0 35 AO 45 * — 0.256 Sec Draft Gear Cycle ' Test Gear No. 18 in Car A. Test Gear No. 17 in Cor B. Impact Velocity=0.92 M y PH. Car A y- 4.075 Ft Lbs. O I ' ■Ul._. Car B b £ r~ 976 Ft Lbs, each ■2123 Ft. Lbs. Work. Done ■17/5 Ft Lbs. -.311 Ft. Lbs. -2049 Ft. Lbs. Work Absorbed figure 79h -55 45 -m Sec. Gear Compress. -0.072- 1 -35 Sec Gear Re/ease -0./3F 0.203 Sec. Draft Gear Cycle—* ■5 100 80 60 40 | tr-80.638 Ft Lbs. Test Gear No. 18 in Car A. Test Gear No. 17 in Car B. Impact Velocity =405 M.RH. s^-CorA Ft. Lbs. each 35.13/ Ft Lbs. 20 CarB^^^ 7,3/7 Ft. Lbs. 1 20 ""**s 38.190 Ft. Lbs ■>rk Absorbed ^-40J54b Ft. Lbs. Work Done kv .0 Sec Gear « ( 5 .10 Compression .15 20 .25 30 35 Sec Gear Release 40 AS f/gure $ Sec Draft Gear Cycle- ~~ 79/ ' Time— Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed during the draft gear cycle. Figs. 79g, 79h and 79j — Energy Curves, Cardwell G-25-A Gears Draft Gear Tests of the U. S. Railroad Administration 205 soc So/id Buffer in Car A. Test Gear No. 17 in Car B. Impact Ve/ocity-2.97 M./?/i. 400 / 300 / / I \ ^ figure 79k SecGegrCgmpressiof A ? iS 20 2£ ■30 35 AO 45 * 0073 «- —0.1 *SS SecDrai f Gear Cycle. > lest Gear No. /8 in Car A. Test Gear No. /7 in Car 3. Impact Velocity- 0.92 M. PH. I ^100 —0/3/ Sec. Gear Be/ease- 0.203 Sec Draft Gear Cyc/e - figure 79/ -w 45 700 ♦- "Test Gear No. /8 in Car A. Test Gear No, /7 in Car B. frnpact Velocity »4.Q5 M.PH. sot 400 30C A f , 100 J V V figure 79m JOS JO Sec. Gear Compression JS 2( 9 A 0280 Sec C s zsb Js 4 45 Q^r «5 * J' / 1 i \ a .5 / / X 1 | £ t 1 / <3 < i ». 1 V 3 i y figure 80c to! . ,•>,,•> Sec CH< -8427 Ft Lbs. each car *r2.666 Ft Lbs. -Cor B r /6J00 Ft. ^Lbs. ? Work Absorbed 18.454 Ft Lbi Work Done \ figure 80& .05 Sec. Gear Compression .10 *5 .20 Sec. Gear defease .2 5 .30 35 4 7 45 'ec Draft Gecu . Test Gear No. 3 in Car A Test Gear No. 2 in Car B. Impact Velocity =1.13 M.FH ■6.150 Ft Lbs. CarA- 735B Ft Lbs, each car ■Car B 3.129 Ft. Lbs.-^ 3440 Ft Lbs. Work Done 2.919 Ft. Lbs. Work Absorbed 102 Ft L t 5 .05 iO JS 0/73 Sec. Geor Compress/on ' 0.247 Sec. Gear Release S 0.420 Sec. Draff Gear Cycle 45 figure 80h 80 GO 40 4SZ-65437 Ft Lbs. Test Gear No. 3 in Car A. Test Gear No. 2 in Car 3. Impact ; Ve/ocity =3. 65 MJPrt. ^\fCar / \ 0~ w 2 / Figure SOr? t 'secGtpJ. impress. /O /5 20 25 30 35 40 45 - 0/66 Sec. Gear &e/ease A -0.25 Sec. Draft Gear Cyc/e- 0.347 Sec Draft Gear Cyc/e- 7/me — Seconds Curve D, determined from superimposed car-movement curves, represents combined draft gear movement and yield of car bodies. Curve C, obtained by eliminating car body yield from curve D, represents true combined movement of both gears. represents movement of Curve B, traced on small dru gear in Car B. Curve A, derived from curves C and B, represents simul taneous movement of gear in Car A. Fics. 80n, 80p and 80q— Time-Closure Curves, Westinghouse D-3 Gears 214 Draft Gear Tests of the U. S. Railroad Administration 40C So/id Buffer in Car/4 Test Gear Na2 in CarB Impact l/e/ocifv=ze6MP* { o^n" 46 too % -17Q000* Gear A/a 2 Car- B t^/oo * figure A/a v? ' Can W , Gear Closure — Inches. Figs. 80r, 80s and 80t— Force-Closure Diagrams, Westinghouse D-3 Gears Draft Gear Tests of the U. S. Railroad Administration 215 0. 220 Sec Draft Gear Cyc/e — 77 me — SeconcTs Fig. 81a— Car-Movement Curves, Superimposed, Gould No. 175 Gears These Curves Drawn by Cars in Test 216 Draft Gear Tests of the U. S. Railroad Administration Test Gear No. 4Z in Car A 7est Gear No. 4/ in Car B Nomina/ impac-f Ve/ocity ■ = l m.ph. figure 6/6 lime — Seconds. Tesi- lesi- Gear No. 42 /n Cor A Gear No. 41 in Car B C/osing Speed Car 266 M.PHT^^y 1, ^CarA 0.797M.PH. 5 ° 1 * b h' y^ 4! 1 * I * a I / 1 ■> 8 5 ~kz 1 l' 5 1 f, ^ / 4 / > figure 6/c 4 f OS JO , q/j4 Sec Gear Compression % .1 S ZO .25 JO .JS 40 .45 Sec Draff- Gear Cve/e. 4, «„. Time — Seconds. Figs. 81b and 81c — Car-Movement Curves, Superimposed. Gould No. 175 Gears These Curves Drawn by Cars in Test Draft Gear Tests of the U. S. Railroad Administration 217 0720Ssc. Draft Gear Cyc/e Tesf Gear No. 42 //? Car A. Test Gear No. 4/ /n Car 3 Impact ]fc/oc/ty=356km idftk i ^sOTrfxat TV ZarA 'V^'V ^-3.8i 9 Ft per sec CorS-xf S *^ W ^-^ a -j *-//7 Ft per^ec. T figure 6/f as /b Sec Gear Compress/on ■15 2t 1 2i Sec Gear £ Gear Cyc/e -, 30 35 40 45 * 0//4 * ■ •* 0.327 Sec Draft 7/me— Seconds Dotted lines represent instantaneous car velocities as de- termined from the original car-movement curves. The irregularities are due in general to vibrations of the car structure induced by draft gear action. Full lines represent the mean velocity curves. Figs. 81d, 81e and 81f — Velocity Curves, Gould No. 175 Gears 218 Draft Gear Tests of the U. S. Railroad Administration -0327 Sec. Draff Gear Cyc/e~ 7/me- -Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed during the draft gear cycle. Figs. 81c, 81h and 81j — Energy Curves, Gould No. 175 Gears Draft Gear Tests of the U. S. Railroad Administration 219 Test Gear No. 42 /n Cor A. lest Gear No. 4/ /n Car a. impact Ve/odty=0.96 MPfi. /o — — 0/43 Sec Gear Compress/on - -0.244 Sec. Gear f?e/ease- 0.392 Sec. Draft Gear Cyc/e- figure 8/1 45 05 10 Sec Gear Compress/on « 0.//4 MGear No. 42 /n car, Gear No. 4/ /nCar 1 ... ?ct ye/oaty=3.S6 . 0327 Sec. Draff Gear Cyc/e- T/me—Seconcts Figs. 81k, 81l and 81m— Time-Force Curves, Gould No. 175 Gears 220 Draft Gear Tests of the U. S. Railroad Administration 4 So/id Buffer //? Cor A ' lest Gear No. 4/ in Cor B /mpact Ve/ocitv - 2.72 MPH \C y B figure 6/n o OS Sec. Geor Compression .K> .IS JO ~.*~ Sec. Gear /?e/eose. ■ZS .30 .3S .<*o .*. *-0.O74 \—Ufr 0.22L ■s Sec. Drvry- Gear Cyc/e. „ Test Gear No. 42 in Cor A Test Gear No. 4/ in Car B //rpoct Ve/ocify=.S6 MPH. O 302 Sec - Dnafi i~ Ge<»" Cyc/e. <5 Test Gear No 42 fn Cor A Test Gear No. 4/ in Car B //npact Ve/oc/tv = 35S MPH O / V ^ ... -\ \ \ ^ V /B B **N ^ ^v\ //^~^ A ^ K figure 8/q ■OS 10 O f/4 Sec Gear Coi>V>ression.„ IS .20 ZS .30 n ii? Sec. Gear Re/ease. 3S -fO .4i O 321 Sec Drcr + Geon Cvc/e. 71/ 7?e — Secot 70S. Curve D, determined from superimposed car-movement curves, represents combined draft gear movement and yield of car bodies. Curve C, obtained by eliminating car body yield from curve D, represents true combined movement of both gears. Curve B, traced on small drum, represents movement of gear in Car B. Curve A, derived from curves C and taneous movement of gear in Car A. B, represents simul- Figs. 81n, 81p and 81q — Time-Closure Curves, Gould No. 175 Gears Draft Gear Tests of the U. S. Railroad Administration 221 600 Sp/tf BufYbr /n Cor A. Z3 Z 500 /mpocr \fe/oc/ry=272 M.P/i. 400 GOQOOO 1 * 300 200 figure <0 6/r si / 7 3 Gear C/osure — /nches 500 400 300 § 200 f i /oo tsf Gear No. 42 /n Cor A. , s/ Gear No. 4/ in Cor Sr- /mpocT ife/oc/ty=0 .96 Mrfi figure 8/s r W. ^PC4Q000# ^ feS&g^fc W No. 4Q Car A / 2 Gear Closure — /nches Gear C/osure — /aches Figs. 81r, 8ls and 81t — Force-Closure Diagrams, Gould No. 175 Gears 222 Draft Gear Tests of the U. S. Railroad Administration 1 1 ■ So/id Buffer in Cor A. Test Gear No.38 in Car B. Time— Seconds Fic. 82a — Car-Movement Curves, Superimposed. Murray H-25 Gears These Curves Drawn ry Cars in Tests Draft Gear Tests of the U. S. Railroad Administration 223 Time- 5econd5 Test Gear No. 39 in Car A Test Gear No.3£> in Car B Time-5econd5 /ygure 62c Figs. 82b and 82c— Car-Movement Curves, Superimposed. Murray H-25 Gears These Curves Drawn by Cars in Tests 15 224 Draft Gear Tests of the U. S. Railroad Administration /•Aoeft per set, Solid Buffer /h Car A. Test Gear No 38 //? Cor B. Impact Ve/ocity=2.76MPff -^ *~CarA Do ,-—£5- ■■r-.'V.i, 23? ft. per sec )""'» f*n* 7M H-, vSec-fl 6;F~ ■23961 FT LbS Work Done Two Gears QV 874 Ft Lbs. Work Absorbed Two Gears /vgure 82h ^ Compression ).7S7 Sec Gear ee/ease- -0.3S3 Sac. Draft Gear Oyc/e- o 397 Sec. Draft Gear Cycle - Time— Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed during the draft gear cycle. Figs. 82c, 82h and 82j — Energy Curves, Murray H-25 Gears 226 Draft Gear Tests of the U. S. Railroad Administration 6C0 Solid Buffer in Car A. Test Gear No. 38 in Car B. impact Velocity =216 M.Prt. 400 300 2C0f 100 figure 62k ■05 Sec Gear Comgrtssior, ■10 .15 .20 25 .30 35 40 4i . Draff Gear Cy Test Gear No. 39 in Car A. Test Gear No. 38 /n Car B. Impact Velocity =0.98 MRU. figure 621 ■OS .10 0J26 Sec. Gear Compression- -0.257 Sec. Gear Release -0.383 Sec Draft Gear Cycle- 600 Test Gear No. 39 in -Car A. Test Gear No. 38 in Car B. Impact Velocity = 3.4G M.PH. 100 1 figure 82m OS ft ■ — 0JZ7 Sec Gear Compress/c ) 15 .20 2 5 .3. Gear &eleas Draft Gear C 3S A 45 "-"-" ~""' y^lc Time — 'Seconds Figs. 82k, 82l and 82m— Time-Force Curves, Murray H-25 Gears Draft Gear Tests of the U. S. Railroad Administration 227 5o//c/ Suffer in Car /9. Test Gear No. 35 in Car 3. Impact Velocity -Z7GM.RH. c x~ h-Jf figure S2n 1 .OS 10 15 ZO . ,^-,sec. Gear Release ZS .50 35 .40 .45 « Q ...jSec. Praft6ear Cycle Test Gear No. 39 in Car A. Test Gear No. 38 in carB. Impact Velocity =0.38 M. P. H. 1 ~~*di*c ^ —H. Time — Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed during the draft gear cycle. Figs. 83c and 83j — Energy Curves, Christy Gears Draft Gear Tests of the U. S. Railroad Administration 233 600] soo 3 Sear C/osc/ne — /nches 600\ 300 -2.23- -ZQ7- 7&st Gear No. £3 in 'Car A. lest Gear No. 5 2 /n Car 3 impact Ve/od/ty=373 M.Pti 0/23 Gear C/osure — //?c/?e3 Figs. 83r and 83t — Force-Closure Diagrams, Christy Gears 236 Draft Gear Tests of the U. S. Railroad Administration 4S 0.237 77me — Seconds Fig. 84a — Car-Movement Curves, Superimposed. Miner A-2-S Gears These Curves Drawn by Cars in Test Draft Gear Tests of the U. S. Railroad Administration 237 cfjft t<>1 fi* 1 Tesi- Gear Na21in Cor A Test Gear Na26in Car B Nomina/ /mpoc-f Ve/oc/fy /MPH Compression ^^ Sec Dr . Qft Geon C yc/e 17me — Seconds Figs. 84b and 84c — Car-Movemi vr Ci rves, Superimposed. Miner A-2-S Gears These Curves Drawn by Cars in Test 238 Draft Gear Tests of the U. S. Railroad Administration Test Gear No. 27 /n Car A lest Gear No. 26 /n Car 3. Impact Ve/oc/ty=/.07Mr°N -/.S7 Ft per sec ■Car A 0.98 Ft per er sec T" /-Cor A >v /V 3/ f Ft. per .sac.^ } 232 Ftp ?r sec ; •- ^S^ k ***»^^ /.2A Ft oe, l~zT' "C-Sr B figure S4f \ Sec. Geo S /O r Compress/on & 20 2*5 30 35 40 „,<,., Sec. Gear Re/ease 45 I '■ 0.425 Sec 7. Draft Get ?/- Cyc/e — lime — Seconals Dotted lines represent instantaneous car velocities as de- The irregularities are due in general to vibrations of the termined from the original car-movement curves. car structure induced by draft gear action. Full lines represent the mean velocity curves. Figs. 84d, 84e and 84f — Velocity Curves, Miner A-2-S Gears Draft Gear Tests of the U. 5. Railroad Administration 239 60 So//d Buffer *? Car A 7est Gear No. 36 in CarB /mpoc-f Ve/octtv 2.47MPH ^JQ/OSfrLbs ^J 20 k At '6 56 ft Lbs Idl 7407rtLbs. r2,/67rtLb&. O < ^ i -« «n»_™ 1 - J ~/3 l 287FrLbs. Wor/c Absorb*?. 40 JS295rt.Lbs Work Done 1 fvgure 64g 05 JO /S 20 25 m „ or . Set? Gear' .1 n , Q -, Seo. Gear- /do/ease. JO 35 40 46 0SS Corrpress/on ' Q/9 ^ Q "S7 S *° Draft Gear Cycfa. oS /o • Q/33 ^ 9C ( ^ ear Compression. lesf Gear No. 27 /h Car/I 7esf Gear No. 26 /h CarB Jepacr Ve/oc/fY~32/ M.RH. Q.4C5 SifCr ° rcrfi ' Goay ~ C Y C, ° Wme — Seconds Full liru-s represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed during the draft gear cycle. Figs. 84c and 84j— Energy Curves, Miner A-2-S Gears 16 240 Draft Gear Tests of the U. S. Railroad Administration 600 4O0 300 So//d Buffer //? Cor A TesT Gear No. 26 //? Car B. Impact Ve/ocitv=247MJ?N .05 0.035 Sec Gear Compress 45 20 25 0./S2 Sec Gear Re/ease 0.287 Sec Draff Gear Cyc/e- 45 400 3*» lest 6 ear No. 27 /n Car A Test Gear No. 26 //pGorB. fmpact Ve/oc/tv^Q7/^Pr/ j> Sec. Gear- &e/eose. -S\ 5 .30 .35 .40 -as ?"""" Compress/on - 0. 2 ,-, S* c. Drcrry- ( ?st//~ Cyc/e. „ Tes-f Gear No.81 in Car A Tesf- Gear No.26 tn CarB /rnpaci- Ve/ocfj-y~=3.2l M.PH. 0-425 "TTme — Seconds Curvf I), determined from superimposed car-movement curves, represents combined draft gear movement and yield of car bqdies. Curve C, obtained by eliminating car body yield from curve D, represents true combined movement of both gears. Curve B, traced on small drum, represents movement of gear in Car B. Curve A, derived from curves C and B, represents simul- taneous movement of gear in Car A. Fics. 84n, 84p and 84q — Time-Closure Curves, Miner A-2-S Gears 242 Draft Gear Tests of the U. S. Railroad Administration i I l 400 300 200 /OO 600 500 400 300 20fr /OO So//of Buffer /n Car A. -2,50- Test Gea r No. 26 /n CarB. impact , Ye/oc/ty=247 MPtf. T/35,000* / 2 Gear C/asure — /nc/?e$ Figure 84r ■'-„ -2S9" — t <~'*r i i Test Gear No. $7 In Cor A. 1 Test Gear No. 26 //? Car B. ^ K fmpact Vebc/ty=32/ Af.P/i. \ to 1 : i JCVJ < i k 1 II ■\ Gear C '/osecf . |J5> /ub.uuv**-—^; LGeor C/osed WO* [r T r-— J rigor eS4t (Gear C/osure - /rcft^s Figs. 84r and 84t — Force-Closure Diagrams, Miner A-2-S Gears Draft Gear Tests of the U. S. Railroad Administration 243 77me — Seconds Figs. 85a, 85b and 85c— Car-Movement Curves, Superimposed. Waugh Plate Gears These Curves Drawn by Cars in Test 244 Draft Gear Tests of the U. S. Railroad Administration 5o//d Buffer /n Cor A Test Geor No. 49 /n Car 3. /mpact Ye/oc/?v=/.e4MP/i. s~234Ftt o&r sec in ^s^-QjrA \L -—/.4/ Ft per sec CarB^ '^^ 0S5_Ff per sec figure OS 10 is 20 Sec Gear Compress. \—Sec. Gear Re/eose 0/35 ^^ 0.230 Sea Draff Geor Cycle - 25 30 35 40 -4S T/me— Seconds Dotted lines represent instantaneous car velocities as de- determined from the original car-movement curves. The irregularities are due in general to vibrations of the car structure induced by draft gear action. Full lines represent the mean velocity curves. Figs. 85d, 85e and 85f— Velocity Curves, Waugh Plate Gears Draft Gear Tests of the U. S. Railroad Administration 245 So/id Buffer /n Can A lest Gear No. 49 th Car B /rnpacf Ve/oc/f y=/.94 M.f>H /2/t3drtU>e. ^S.729 Ft Lbs. Work Absorbed figure 85g .25 30 JS 40 •<*d 7est Gear No. SO/n Cor A Test Gear No. 49 in Car 3 /mpacf \Se/oafY=3.Q2 M.PH. 05 /O j,,~ Sec Gear Compress/on. t \ m Sec Draft- Caar Time —Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed luring the draft gear cycle. Figs. 85c and 85j — Energy Curves, Wauch Plate Gears 246 Draft Gear Tests of the U. S. Railroad Administration 600\ 400 Bsf Geor No. 50 /n Cor A. Test Geor No. 49 /n Car 3. import Ve/oc/tv=/.06 A/JW \goc uoo \ .05 JO JS .20 2 5 .3 1 Sec. Geo .35 40 45 1 -0.4/9 Sec. Draft Geo> $ -0292 Sec. Draft Geor Cyc/e- T/rr?e —Seconds Figs. 85k and 85m— Time-Force Curves, Waugh Plate Gears Draft Gear Tests of the U. S. Railroad Administration 247 s So//d Buffer /n Car A lesi~ Gear Na49/n Car B /mpac-f Ve/odi-v=f.34MPH 4- 3 C , D 2 S^ / figure 6Sn .05 J J5 .20 ,-,/-,- Sec. Gear- Re/ease. .25 .30 .35 .40 .45 ■°°^Compre ss/on. 0.23C Sec. Draff Gear- Cyc/e. Test Gear NaSOin Car A les-f Gear A/o.49/n CarB //n paci" Ve/oc/-fy*=/.OGMPH a Test Gear /VaSO/r? Car A lesr Gear No.49 /n CarB /mpacf Ve/ocii-v=3.02MPH 6 5 4 3 / 00 40U 300 ZOU JOO figure 66k .05 Sec. Gear Compress^ — °^- 0. 235 /O J5 .20 Q/36 Sec. Geor /rb/eose-^ •Sec. Draft Gear Cyc/e- — .25 .30 .35 40 45 0.323 Sec. Draft Geor Cyc/e 7/me Seconds Figs. 86k and 86m — Time-Force Curves, Bradford K Gears Draft Gear Tests of the U. S. Railroad Administration 253 +> J S *., <5 So//d Buffer in Car A lest Gear Na46in CarB //ryaaci- Ve/oc/-rv-2.04MPH C^^T- O ^^ B ^^^ ^r figure sen .05 Jt ) JS .20 . -,.,- Sec Gear- Re/ease. u .25 .30 .35 .40 .45 " uajU Compress/on. r- 0.2 -,,- Sec Dr-crff- Gear- Cyc/e M 7T/ne — Seconals Curve D, determined from superimposed car-movement Curve B, traced on a small drum, represents movement of curves, represents combined draft gear movement and yield gear in Car B. of car bodies. Curve A, derived from curves C and B, represents simul- Curve C, obtained by eliminating car body yield from taneous movement of gear in Car A. curve D, represents true combined movement of both gears. Fig. 86n, 86p and 860 — Time-Closure Curves, Bradford K Gears 254 Draft Gear Tests of the U. S. Railroad Administration 400 300 200 So/fof Buffer /r? Car A. -2.45' Test Gear No. 46 '//? Car 3. /mpact ^ \fe/ocity=2.04 MP/i 207000*i %soo Gear • C/osure — /nc/?es m i - ^400 | Test 6 i — *f^ — t — ?ctr No. 47 //? Car A. Test Gear/va *to /n uar o. Impact Ve/oc/t\/=2J5MPff. Q) D 300 k 200 Gear C 270.00 :/OSeaf » i ^1 x_ Gear f 2?OL SSr" i\ ,i =. 66t Gear C/osure —/nc/iee Figs. 86r and 86t — Force-Closure Diagrams, Bradford K Gears Draft Gear Tests of the U. S. Railroad Administration 255 A So//d Buffer /n Car A Test Gear No.SS/n CarB Car B /.54M.PH 1 C/os/ng Speed Cor/H 0.35MRH. Mr- 1 1' / vj. "sir fvL V (0 1 figure 67a k M .OS - OD7~' ^ ec Gear m JO ./S .20 .2S .30 .35 40 #£ _ n/i>£> Sec Gear /Pe/eose. F ^"""Co/7pr-esston ~~ j~Sec Draft Gear Cyc/e, TTme — Seconcte Figs. 87a, 87b and 87c — Car-Movement Curves, Superimposed, Harvey Springs These Curves Drawn by Cars in Tests 1? 256 Draft Gear Tests of the U. S. Railroad Administration Solid Buffer /n Car A. Test Gear No. 55 /n Car 3. Import Ve/oc/ty=l.97 M.Prf. 2.26 Ft per sec. ■ — 0.5/ Ft per sec figure TS7c/ OS Sec. 6eor Compress. - —0.077— ./O V5 Sec. Gear Re/ease 0/26 0.203 Sec. Draft Gear Cyc/e- 25 30 35 40 45 45 0.296 Sec. Draff Geor Cyc/e 7/me— Seconds Dotted lines represent instantaneous car velocities as determined from the original car-movement curves. The irregularities are due in general to vibrations of the car structure induced by draft gear action. Full lines represent the mean velocity curves. Figs. 87d, 87e and 87f — Velocity Curves, Harvey Springs Draft Gear Tests of the U. S. Railroad Administration 257 Sofia/ Buffer in Car A Test Gear No. 55 in Car 8 impact Velocit y —i.S7 M.RN -/(705 TfrLbs. i 6Q/r*Lbs. ~e.s69rf-.ibs. Hbrk Absorbed. F/gure 87g 25 .30 .35 40 45 Test Gear No. 56 in Car A lest Gear No. 55 in Car 8 impact- l/e/ocity = i.02 M.RH. /OO- 80 .05 JO , q //7 Sec. Gear- Carrpress/on. 7est Gear No, 5€in CarA 7est- Gear No. 55 in Car B impact Veiocity=a.33 MPH. 20 ^S Gear &o/eose. 4S - 0. 29G ^ ec Draff Gear Cyc/e TTme — Seconds Full lines represent the instantaneous kinetic energy of the moving cars. Dotted lines represent the energy stored and absorbed during the draft gear cycle. Figs. 87c and 87j — Energy Curves, Harvey Springs 258 Draft Gear Tests of the U. S. Railroad Administration 600[ T/me— ^Seconds Figs. 87k and 87m — Time-Force Curves, Harvey Springs Draft Gear Tests of the U. S. Railroad Administration 259 6 So/td Buffer tn Car A Test Gear A/o. SStn Car 3 /mpact Ve/oc/tv—/.S7MfiH J V P_ figure 87n .OS ./ J5 .20 .25 -30 .-35 ftO .-45 f->Q Sec. Gear- Releas^ )2Q3§*c Qr-eff- Gear- ^ Cyc/e. ' oo7-r Compress . oA . » Test Sear No.SC/n Car A 7est Sear Mo.5S/n Car 8 Jrnpac-f Ve/oc/f y =*/.0 2M.PH (5 Test- Sear NaSStn Car A Test Sear No.SSin Car 3 /mpoc-r Ve/oc/+ y=2. 33M.PH. 45 ITme — Seconds Curve D, determined from superimposed car-movement curves, represents combined draft gear movement and yield of car bodies. Curve C, obtained by eliminating car body yield from curve D, represents true combined movement of both gears. Curve B, traced on small drum, represents movement of gear in Car B. Curve A, derived from curves C and B, represents simul- taneous movement of gear in Car A. Figs. 87n, 87p and 87q — Time-Closure Curves, Harvey Springs 260 Draft Gear Tests of the U. S. Railroad Administration 400 300 So/taf Test Gear No. 55 ' /r ? Car 3. 200 too -1.76"- ^uffer //? Car A /mpact ]/e/oc/ry=/.37 MrVf. 243,000* / 2 Gear C/osure—//?c/?e$ 600 500 400 300 200 /00 -/.76'± 7esf (jear A/b. 56 //? Car A\. Test Gear No. 55 A cj?r]s. /mpact l/e/oc/ty=233 M$ff. 245,000* Gear C/ osed Car B- Test Gedr~No. Car B- Si? -300,000**- . I ^-Gear C/oseaf lest Gear A/oTt56' Car A Figure 87t Gear C/osure —/nc/ies Figs. 87r and 87t — Force-Closure Diagrams, Harvey Springs Draft Gear Tests of the U. S. Railroad Administration 261 6 5 4 \ t 1 3-t CarB Q98HPH 3 Sec Gear Compress/on 1 * or, L .25 30 35 40 t4i> T „ Sec. Gear- Re /ease. **• Q/64 ^ \-crrr Gear- Cyc/e. /*" t t < i 3 5 \ S3 9 * /T&t/re 86c / .Off //-»« Sec. Goon Re/ease. 5 40 .46 - — 0. 342 Se c. Drcrfr Gear- Cyc/» 77me — Seconds Curve D, determined from superimposed car-movement curves, represents combined draft gear movement and yield of car bodies. Curve C, obtained by eliminating car body yield from curve D, represents true combined movement of both gears. represents movement of Curve B, traced on small drum, gear in Car B. Curve A, derived from curves C and B, represents simul- taneous movement of gear in Car A. Figs 88p and -Time-Closure Curves, A. R. A. Class G Springs Draft Gear Tests of the U. S. Railroad Administration 265 soo 400 -/.94 1 Test Gear No. 5^ 7/7 Car A. Test Gear No. 58 /n Car 3. 300 fmpact , Ve/oc/fy=/86 'MP//. 200 /oo figure -60.000* oac '-Test Gear No}S8-CbrB / 2 3 Gear C/osure —/nche& Fig. 88t — Force-Closure Diagram, A. R. A. Class G Springs 266 Draft Gear Tests of the U. 5. Railroad Administration '*■? -x Nsi S^TZ .£> *SN 4 \l ^ i ^\ */ ■*? SaL a>\iyo ^V -cS ^ ^v ^/ s ^v -±-\ Q?/Z ^ \T5^ [O 1 ^\ ^t *W °Y c\_\A AiA ■"o\ X 4 x3 ■7" *r\ v\% «\ ^\ &C UA\\ <^" f*\ ,V/ Iv > \ \ s V \ \ > \ V - fcl \ X i- *tv V s !- P \_V *^r N'- 'iV *S\ *J V ^L . \ °\ XL A \ «> ft 4--\ \r -v-\ A <: 3 v^ -^] iU< o\ kl o-\ X" 31 ^ — \ .«J_ coe \ .^rz "A'S. $1 u\_ *o V ^/ o\ -^ (°ji ~^r\ *l Vjl \ \ \\ t>v \ \\ \ \\ x> \ V ^>V \ \ V"\ \ V I \ ' ^ u £ 'H'd'H fy'.3°l*A ^ 00 ^> '9q-j 'JJ 9pUD£-nOL/J_ -fifijdUJ Draft Gear Tests of the U. S. Railroad Administration 267 -Is — l £ ^~- c- c Note: This curve represents the peaks of forces developed at the different speeds p c. •S I § s $ X- £l %1 H h ■fvS "~o\ "^A ^\ ^s j£\ VI *\ i ^S m ^ c $Sr <=»> Si -\ ^ \< ■& — o l^N^ 1 o^ -\— V £ y Kh I i_ \ \&- ■v 1 I o 1 ^r |j 1 W 1 <> A V "> ■J.U3J Jdfj ^ 00 ^ 'S-9tJDU/-/dj1DJJ_ CvJ o4 <• *^ '9qj/0 S-pUJOS-nOLJJ_ -BOJOJ 4? H~. ts 0) Note: This curve represents fhe pea of forces developed af fhe different speeds • 1 "§ ^L__ tfl S^ A \ C.1 \ \ m .Q . _V o\ :§ 1' \ v> ts\ c s\ <»\ ^ o\ § °\ c^ G| *3 S^ ■^. kfc ^\ o ctt .3 °\ a x\_ 1 l£j\_ ^ ^.\ o\ ^\ £ H-' *t **^ \ «j ^C ^\^ -*5 C °QL «o\ k.^- V:C ^V ^ r\ \ *> < o ^l ^ i\ 1) ^5p\ H ^n cA H ^v «^L o *\ til £1 °y v Y 00 V£> OJ •J.U30 Jdd ?dcjDuj-idAnjj_ *> * -s-g-fjo rpurts-noyx _ aouioj 268 Draft Gear Tests of the U. S. Railroad Administration ] <5* ■ / <>/ \yz ,VJ / w^ t $t •* ^ 1 ^?t *M P^t ^\ tt ^ ft Jt *< 4 - o - *a &t ^ J?t K / > ^t u A' ^/ isl 7 t * ^ ^ CM 2 <5> -C -»| k L/O//. DJJ. dU3(j JOQ i / | / f ' 1 1 i L_ 1 / I \ F \? I ' s \ - S S ' Al s ca \ *•* "4 s £ \ o — \ S of ^^ y IV H5 3 { X 5. - V .J r\ ^ o\_ VJ I \\ ^~^A>^- '"3^ F "I >^\ -■"> tvE / o\ zj ^X / "^L / -Sl\ v-\ ^ vl Cl -°\_ ^-\ ^\ VI I vi (VJ^ o J, ^ ^ *> cvi TdL/OU/ - 3JS7S-0/J JOBS) APPENDIX A REPORT OF DRAFT GEAR TEST MADE ON NORFOLK & WESTERN RAILROAD, NOVEMBER 4, 1918 Object of Test This test was conducted for the purpose of determining the relative amount of draft gear movement when a car having a draft gear with an easy compression curve is coupled to a car having a draft gear with a relatively stiff compression curve, and to determine the probable number of foot pounds of work done by each when shocks occur. The test was made on the Norfolk & Western Railroad in a freight run from West Roanoke, Va., to Vicker, Va., a dis- tance of 38 miles. The test was conducted jointly by the Engineer of Tests of the Nor- folk & Western Railroad, and the Section of Inspection and Tests of the United States Railroad Administration, a representative of the National Malleable Castings Com- pany being present to assist in the handling of the recording instruments, which were loaned by that company for the purpose of making the test. Equipment Used The train consisted of 44 miscellaneous cars, the tonnage being 1,748 tons. From West Roanoke to Elliston, over an un- dulating grade, it was handled by Norfolk & Western locomotives 422 and 1477 on the head end, the first of these being a Class M of 40,000 lb. tractive effort, and the second being a Mallet, Class Zla, of 73,000 lb. tractive effort. At Elliston, the foot of an ascending grade of 1.32 per cent, the Class M locomotive was put on the rear end to act as a pusher, and at Christiansburg, the top of the grade, the Class M was cut off entirely. From Christ- iansburg to Vicker is a descending grade. The cars from which the records were made were Norfolk & Western 100-ton gondolas, empty, being the first and second cars in the train. The rear end of the first car, Norfolk & Western 100,147, was equipped with a Sessions type K draft gear, and the coupled head end of the second car, Norfolk & Western 101,534, was equipped with a National type H-l draft gear. Both cars had experimental M.C.B. type C couplers, No. 5 contour, and the draft gears were especially prepared for the test. All slack was eliminated from the draft gear attachments. The Sessions K gear as it was applied to the car had T 5 g in. initial compression, the National type H-l gear being applied with but enough initial compression to take out all slack. Holes were cut in the floors of the cars for the ap- plication of the recording devices and for observing the action of the draft gears. Preparation of Draft Gears The Sessions type K gear used was re- moved from a Norfolk & Western cabin car and was in practically new condition, the friction surfaces being worn to a smooth bearing, but not enough to remove all of the irregularities of manufacture. The friction faces were wiped off and the gear set up in the 200,000 lb. testing machine of the Norfolk & Western Railroad, and an attempt made to close it. Repeated sticking and bombardment of the gear led to the application of a thin coat of tallow on the center friction block to enable the closing of it in this machine without the — 269 — 270 Draft Gear Tests of the U. S. Railroad Administration necessity of sledging the gear. The clos- ing speed was T \ in. per minute. This treatment of the gear was necessary also to give the easier compression line desired for the purpose of the test, since as pre- viously stated the primary purpose of the test was to observe the action of a stiff gear when coupled with an easy 'gear. The greased center friction block did not en- tirely eliminate sticking of the gear, the compression curve shown in Fig. A-2 being plotted directly from the readings taken from the beam of the static machine after a number of preliminary compressions to insure uniform action. The dotted com- pression line indicated on this curve is worked to in this report as the probable compression line in a quick closing of the gear. The National type H-l gear was removed from the same car, No. 101,534, to which it was reapplied for the test, and after wip- ing off the friction wedges to remove coal dust which had fallen over the gear while cutting the hole in the car floor, the gear was run down as far as the 200,000 lb. ma- chine would compress it for a number of times. The compression curve shown in Fig. A-l for this gear was plotted directly from the readings taken from the beam of the testing machine. It should be noted that whereas this gear is designed for a total movement of 2% in., it could only be compressed to .93 in. in this 200,000 lb. machine. The action of this gear in the static machine was smooth and regular. Recording Apparatus The records of coupler or draft gear movement were made upon a moving rib- bon of paper, one pencil being arranged to draw a datum line on the paper and with provisions for indenting this datum line when desired, as for marking off time increments. The pencil recording the draft gear action was caused to move to one or the other side of the datum line responsive to draft gear action in pulling or buffing, the recording arm being attached to the butt end of the coupler. The original con- tinuous records made in this test are on file in the office of the Engineer of Tests of the Norfolk & Western Railroad, points of interest being abstracted as Figs. A-3 to A-ll inclusive of this report. The connection between the coupler butt and the recording pencil was through a reducing mechanism, so that the following scale should be used for measuring draft gear movement on the cards. 3 3 2 in. offset on record = a /4 in. coupler movement 5 5 sin. " " = y 2 in. " &in. " " =1 in. M in. " « = l%'in. Hin. " " =2 in. The following tabulation gives the rela- tive resistance of the two gears used for various amounts of travel, the loads being those obtained in the static tests and proper allowance being made for the initial com- pression of the Sessions gear. Coupler Sessions K Gear with Movement Greased Center Friction Block National HI Gear % in. 10,400 lbs. 10,400 lbs. Mjin. 20,850 lbs. 37,850 lbs. % in. 44,000 lbs. 116,750 lbs. .93 in. 54,000 lbs. 200,000 lbs. 1 in. 59,000 lbs. Capacity of testing machine reached at .93 in. lV 2 in. 87,000 lbs. travel of National HI gear. 1% in. 108,000 lbs. gear solid Draft Gear Tests of the U. S. Railroad Administration 271 The compression curves, Figs. A-l and A-2, and the above tabulation, are not to be considered as a comparison of the normal action of the two gears, as it has already been explained that the capacity of the Sessions K gear was purposely re- duced for the purpose of the test. Discussion of Cards The portion of the record reproduced as Fig. A-3 shows the action of the two gears, beginning with the train moving on level track and showing the draft gear movements when the train was slowed down for orders and then accelerated. The rec- ord, which should be read from right to left, starts with the Sessions K gear com- pressed 1 in., the National gear at the same time showing % in. of compression. After building up the speed again the Sessions gear stood at % in. compression and the National at % in. In Fig. A-4, with the train moving on a slight ascending grade, the train was brought to a stop for a red signal, the Ses- sions gear moving % in. and the National % in. On the succeeding start, the Ses- sions gear went to 1% in. and the National to 1 in. movement. The Sessions gear stuck and bombarded at two points during this pulling compression. The influence of the bombardment of the Sessions gear is manifested in the diagram of the National gear. The card, Fig. A-5, was made when the train was slowed down for orders, the Ses- sions gear moving % in. and the National gear 1 in. The Sessions gear was sticking during this part of the diagram. On start- ing, the Sessions gear, after sticking one time, went to IVi in. and the National to % in. From the static cards there were required 2,000 ft. lb. of energy to close the Sessions gear this 1*4 in., and 2,053 ft. lb. to close the National gear the % in. at the same time. The card, Fig. A-6, was produced when a stop was made from a slow speed. The card, Fig. A-8, was obtained when the train passed through a dip in the track (Balls Hole) and shows several compres- sions of the gears due to the slack running in and shows also a quick pulling compres- sion of both gears as the locomotive started the train up the grade. As the slack ran in, the Sessions gear was compressed % in. while the National gear was compressed if in. It is presumed that the greater movement of the National gear was due to the Sessions gear sticking. On the suc- ceeding pull the Sessions moved 14 in., while the National moved % in. On the succeeding start, after sticking, the Ses- sions gear moved to 1% in., while the Na- tional gear stood at 1% in. The card, Fig. A-10, was obtained when a sudden stop was made with the pusher on the rear end of the train, the pusher running in the slack against the front en- gine. The Sessions' gear went solid, the movement being 1% in., while the Na- tional gear moved 1^ in. On the suc- ceeding start, which was made on the as- cending grade, the National gear responded immediately to the amount of 1 in. move- ment, while the Sessions gear lagged in action and finally bombarded to iy 2 in. movement. Fig. A-ll shows a typical section of record obtained going up the hill from Elliston to Christiansburg, on a steady pull and at comparatively uniform speed. Both gears stood at 1% in. movement. General The National gear used appeared in gen- eral to be quicker in movement and more responsive to impulses than this particu- lar Sessions gear. In pulling, it is almost invariably the case that the National gear compressed uniformly and gradually, while in most instances the Sessions gear 18 272 Draft Gear Tests of the U. S. Railroad Administration obtained its final position after one or more bombardments. In release both gears re- sponded almost instantly, and in the ma- jority of cases a quick buff produced har- monious action in both gears. It is notice- able, however, that on a quick buff the National gear, even though having a stiff er resistance curve in the static machine, fre- quently shows more travel than the Ses- sions gear. With a slow buff as in Fig. A-5 the Sessions acted through a succession of bombardments. In a continued steady pull, such as repre- sented by the lines in Fig. A- 11 the ab- sence of see-saw movements of any extent was noticeable in both gears. Draft Gear Tests of the U. S. Railroad Administration 273 f z / / £ / •1 / / z > / Fk* A 1 •> r / Sta-ti« Dmo^M NATIONAL HI S^AH, h f IN Thai*- Actio* Tfsrs rv.et w. fW. u t - £ _ = *" 3 SCAR. CLOJURE Fi 6. AE 14 Q z Sl -AT C I 5lA< rRA FA oual *£"* V 1.1 o P.M. >-SESSio*3 66AR Stock — ff — "" , Start Start J vT>?aiij Standing > Brake appc For Stop Datum Lime Matiokal G-ea* _ 1 _ Start p _ Fi*.A7 -— ^ ■DATum Line /SE9li<>N> SCAR Stuck NATIOHAI- GeAi<. F1&A8 Datum Line m) «q ~^ f SLACW j NStACK RUUNIH6 >H /ActionS /At Foot «f Grade, V JV / Datum LiwE N'^^^BSr »" Batuiw LinC STARTi RG.A9 I SgSStOMS GEAR Brake appl S-Runnin* For STOP I P>q-ru m l ^TMjnoMAjC^ ^ea^ Fig.AIO I DATUIVV LlNt. rtf" 4 -■2*" Fie.AII I Chronographic Records of Draft Gear Action in Train Service, Norfolk & Western Railway APPENDIX B TESTS OF CAR CONSTRUCTION In accordance with recommendations of the Committee on Standards, high speed impact tests of car construction were made by the Inspection and Test Section of the United States Railroad Administration at the car impact plant of the T. H. Syming- ton Company at Rochester, New York, February 25 and 26, 1920. The following were present during all or a portion of these tests : B. W. Kadel, assistant engineer, Inspec- tion and Test Section, U.S.R.A. E. M. Richards, special engineer, Inspec- tion and Test Section, U.S.R.A. L. H. Schlatter, representing Draft Gear Committee, A.R.A. J. A. Pilcher, W. J. Robider and John McMullen, sub-committee of Car Construc- tion Committee, A.R.A. J. R. Onderdonk, B. & 0. Railroad. L. H. West, Merchants Dispatch Trans- portation Company. B. B. Milner, New York Central Rail- road. D. S. Barrows and I. 0. Wright, repre- senting the T. H. Symington Company. A total of four tests were made: Tests 1 and 2 to determine the value of the ap- plication of metal draft arms for the rein- forcement of wood center sills. Tests 3 and 4 to show the performance of U.S.R.A. cars at high impact velocities and to determine the relative value, in buffing, of U.S.R.A. draft gear attachments having the separate rear draft lugs, and of draft gear attach- ments having the central back stop casting for distributing the impact force to the car sills. Test No. 1 — Wood Draft Sills The first test was of 40-ton box cars with wood center sills, using N.Y.C. Car No. 214,423 as car A (striking car) and N.Y.C. car No. 226,768 as car B (struck car). The opposing ends of these cars were fitted with wood draft sills. These cars have two 5 in. x 8 in. center sills, two 4!/2 in. x 8 in. side sills and four 4>y 2 in. x 8 in. intermediate sills, with one-piece cast steel body bolsters beneath the sills. The draft sills extend from be- neath an 8 in. x 8 in. oak end sill back to the body bolster, where they abut suit- able pads cast to the body bolster. The draft sills are doweled and bolted vertically to the center sills and end sill. Malleable iron tandem cheek plates are bolted to the center sills and draft sills, and have lugs gained into both the draft sills and the center sills. Sub-sills extend from bolster to bolster beneath the main center sills and these abut suitable pads cast on the body bolster. The cars were equipped with tan- dem spring draft gears with 5 in. x 7 in. old-standard couplers and wrought steel riveted yokes. The coupler horn was allowed to strike a heavy cast steel striking plate, which was bolted to the face of the 8 in. x 8 in. oak end sill, the buffing force on the draft sills thus being limited to the resistance of the two Class G springs, viz., 60,000 lb. The cars had been fitted with new sills throughout for the tests, and the steel ends had just been applied. The cars were loaded with sand to give a total gross weight of 123,000 lb. per car, the sand being partly frozen in the cars. 275 276 Draft Gear Tests of the U. S. Railroad Administration These cars were given tests at successive impact speeds of 4 5, 7, 8, 10, 12 and 14 miles per hour. At 7 M.P.H. the coupler heads began to scale and continued scaling throughout the tests. At 8 M.P.H. the end at the struck end of car B began to bulge out and the one at the opposite end of car B began to bulge in. At 10 M.P.H. the ends of car A began to bulge. This bulging increased throughout the test for both cars. A slip- page of ^ in. could be detected between the draft sills and center sills at 5 M.P.H., but this did not increase during the re- mainder of the test. A slippage of -^ in. occurred between the cheek plates and the draft sills at 7 M.P.H., but this also did not increase as the test proceeded. At the conclusion of the test, the strik- ing end of car A had bulged 1% m - an d the struck end of car B 3% in. The draft sills were shattered where they abut the bolster, but no breakage of either draft sills or center sills occurred. The bolsters slip- ped back % m - during the tests and the striking castings moved % in. each. The coupler carrier irons bent down % in. The coupler horns were not noticeably injured except for some scaling and the striking castings were in good condition. The ends of the center sills, after the test, were dropped approximately 1 in. each, but as this measurement was not checked in ad- vance, it is not definitely known that this occurred during the test. The ends, how- ever, scaled along the bottom edge, which indicates that these ends were straightening out and allowing the center sills to droop. Except for the bulged ends, no particular damage to these cars was apparent and they were fit for service. Test No. 2 — Metal Draft Arms The same box cars were then shifted so as to bring the opposite ends together and test No. 2 made, N.Y.C. car No. 214,423 now being car B and N.Y.C. car No. 226,- 768 car A. The opposing ends of the cars were equipped with metal draft arms, which were built up of angles and channels proportioned to just meet A.R.A. re- quirements. The design was made by the Inspection and Test Section and does not represent the particular details of any pro- prietary device. The metal arm did not abut the bolsters, but a gusset plate was riveted to the top flange of the bolster and to the bottom flange of the draft sill angle, these angles extending back 5 ft. over the bolster towards the center of the car. The tandem cheek plates were riveted to a channel below the main draft arm angles, there being no stop lugs on these cheek plates. The coupler horn was allowed to strike as in the previous test, the striking casting, however, being of malleable iron instead of cast steel. The load on the draft arms at the center line of the coupler was thus limited, as before, to the resistance of the two Class G springs. These cars were given tests at successive speeds of 5, 6, 10, 12, 14 and 16 miles per hour. At 10 M.P.H. the coupler heads were scaling and this scaling continued through- out the test. At 10 M.P.H. also the ends of the center sills began to droop slightly and at the end of the tests had drooped % in. on car A and % in. on car B. No bulging of the ends occurred during this test, al- though the drooping of the sills appeared to result from a straightening of the trans- verse corrugations of the ends. At the 16 M.P.H. run one of the cast steel body bolsters was broken transversely, one center sill was broken an car B and both center sills broken on car A. The center sill breakage in each instance oc- curred over the bolster, the crack develop- ing from the top of the sill. No slippage of cheek plates occurred, but the draft arms as a whole moved an average of % Draft Gear Tests of the U. S. Railroad Administration 277 in. with respect to the center sills. The coupler carrier irons were bent down ■£$ in. and the striking castings moved T 3 g in. on the draft arms. The performance of the cars in both the foregoing tests was unexpectedly good. In each instance after the 14 M.P.H. test both cars were fit for service, the breakage of sills and bolster occurring at the 16 M.P.H. run. The fitting up of the wood draft sills was an especially good job and it is quite probable that extended service would pro- duce looseness, which would not be the case with metal draft arms. In the limited number of tests made it was observed that neither type of construction had an especial advantage over the other. No pulling tests were made, nor was it practical to make a considerable number of lower speed im- pacts, which unquestionably would have produced failure. The comparative merits of the two types of construction, however, are believed to be indicated by these tests at regularly increasing speeds. The results of these tests show the fol- lowing: 1. That metal draft arms do not offer any noticeable advantage, in buffing, over properly applied wood draft arms if the latter are kept tight. 2. It should be observed that the sill breakage occurred in each instance over the body bolster, although the application of the present A.R.A. rule would indicate that the unreinforced wood center sill be- tween the bolsters is of less value than the same sills reinforced over the bolster. 3. That it is permissible to allow the coupler horn to strike in wood car con- struction and probably so in steel cars with wood end sills. 4. That there is a pronounced downward force at the coupler carry iron and an up- ward force at the bolster which may result in deformation or breakage at both points. As both these forces must be added to the static load, cars should be constructed with bolsters rigid enough to resist the upward tendency, and the end sill and carry iron should be securely tied to the end of the car. Test No. 3 — Draft Attachments with Central Stop Casting For this test two 70-ton U.S.R.A. low side gondola cars were used, P. & R. car 7378 being car A and P. & R. car 7379 being car B. These cars have fish belly center sills with steel sides, steel plates, drop ends and wooden floor. Each car was loaded with sand to give a total gross load of 184,000 lb. per car, the sand being partly frozen in the cars. The cars were new and had been equip- ped with Farlow 2-key draft gear attach- ments, T. H. Symington Company's Print F-2437. Flat face dummy couplers' were used instead of the regular couplers. There being no coupler horns, the entire blow was taken through the draft gear attachments. Steel blocks of 54 sq. in. cross section were used instead of draft gears, the full load being taken through this block and being delivered upon the back stop casting through the intervening parts of the at- tachments. The second key had % in - clearance in the cheek plate key slot. The coupler shanks were made of an extra heavy design so as to reduce as far as prac- ticable the deformation and failure of this part. The net areas of the several parts in buffing are as follows: Dummy coupler shank, back of head, 24 sq. in. cast steel. Dummy coupler shank at key slot, 171/2 sq. in. cast steel. (Note — For reference, the type D coupler has an area of 16.9 sq. in. back of the head, and 13.4 sq. in. at key slot.) Front follower block, 17*4 sq. in. mal- leable iron. 278 Draft Gear Tests of the U. S. Railroad Administration Rear follower block, 17% sq. in. mal- leable iron. Yoke, I14 in. x 5% in. (section), 33% sq. in. bearing area against back stop. Back stop casting, 19% SC I- in., cast steel. Back stop casting, 38 rivets through center sills and 4 rivets through bottom bolster tie plate, all rivets % in., total of 25.2 sq. in. in shear. Keys, 1% i n « x 6 in. Malleable iron cheek plates, fourteen % in. rivets each. The cars were given tests at successive speeds of 4, 5, 6, 8, 10, 12 and 14 miles per hour. At 6 M.P.H. the couplers started to scale and deform at the key slots, this deforma- tion continuing throughout the test. At 8 M.P.H. the front portions of the back stop castings showed slight scaling. At 10 M.P.H. this scaling became pronounced and continued throughout the remainder of the test. At 10 M.P.H., also, three rivets at one diagonal brace sheared off and others of these rivets had loosened. At the conclusion of these tests the fol- lowing conditions were found: Condition of Cars The opposing drop ends of the cars had bulged out, both at the top and bottom. In car A the bulging amounted to 3% in. at the top and 2% in. at the bottom. In car B it amounted to 1% in. at the top and % in. at the bottom. On both cars the corner posts, which are formed of heavy bent plates and serve as stops for the ends, were bent from the impact of the load. The up- standing legs of the end sill angles were also bent out from this same force. On both cars the body bolsters at the opposing ends of the cars were bent down at the ends, equivalent to the centers of the bolsters being forced upward. In car A the center sills were also bent slightly from this same condition. The entire ends of the cars were down 1 T % in. for car A and T 5 e in. for car B. The end sill of car A was bowed inward % in. and that of car B, 1 in. Neither of the end sills were bowed down. On car B one of the diagonal braces was sheared and torn loose and all diagonal braces were either scaling or had loose rivets. The floor boards of both cars had shifted 1% in. and the floor clips were dis- placed. These floor clips began to drop off early in the test and do not appear to be a satisfactory type of construction. The floor boards of both cars were crushed at the bolsters and at the end sills from shifting. One intermediate wood sill of car A was shattered from the same cause. At two points on the bolsters of car A cracks developed at rivet holes through the flanged bolster webs. These cracks re- sulted from the horizontal bending of the bolster when the sides of the car attempted to run ahead of the center sill. No spread- ing of the center sills occurred. Condition of Coupler and Draft Attachments Dummy Couplers, cast steel — Shank bent both vertically and laterally, and upset and deformed at key slots. Short- ened an average of % in. each. Cheek Plates, malleable iron — No fail- ure or injury of any kind. Second key had been bearing slightly, indicating momen- tary elastic compression of parts. Back Stop Castings, cast steel — Slipped on rivets 3/64 in. Front end upset 7/64 in. Not injured perceptibly and removal or repairs unnecessary, except that two rivet heads jumped off at the final run. Yokes, wrought steel— No failure or in- jury of any kind. Coupler Keys, wrought steel — Not bent or injured. Draft Gear Tests of the U. S. Railroad Administration 279 Second Keys, wrought steel — Bent an average of 3 \ in. each. Serviceable with- out repairs. Front Follower Blocks, malleable iron — Shortened ■£■$ in. Not injured perceptibly. No repairs necessary. Rear Follower Blocks, malleable iron — Shortened 3V in. Not injured perceptibly. No repairs necessary. In this test the cars suffered more than the draft gear attachments. It is noticeable that not a single part of the attachments was damaged to an extent requiring re- moval or repairs during this test, and that the draft gear pockets had elongated but r /V in. each. The car damage was greater to car A (striking car) than to car B (standing car). The back stop castings of the attach- ments first beginning to scale at 8 M.P.H. this point is taken as the comparative crit- ical speed for these attachments, and a value of 64, or the square of 8, is accord- ingly set for these attachments. Test No. 4 — Attachments with Sep- arate and Independent Draft Lugs Two of the U.S.R.A. 70-ton low side gondolas were used for this test, the cars being new and having the regular U.S.R.A. cast steel yoke and draft gear attachments. P. & R. car 7381 was used as car A and P. & R. car 7380 as car B. Each car was loaded with sand to give a total gross load of 184,000 lb. per car, the sand being partly frozen in the cars. These cars have the regular front and rear cast steel draft lugs riveted to the cen- ter sills, the rear lugs each having twelve % in. rivets and the front lugs ten % in. rivets, and three % in. rivets each. The rear draft lugs, from the drawings, extend to within *4 in. of the bolster center cast- ing, which has twelve % in. rivets through the center sills and four % in. rivets through the bottom bolster tie plate. The same steel blocks of 54 sq. in. cross section were used instead of draft gears, as in the previous test, there being the regular 2 1 / 4z in. followers in front of and behind these blocks, bearing upon the stop faces of the draft lugs. The net bearing area of the followers upon the two lugs, in buffing, is 50 sq. in. The lugs are ribbed to support this bearing surface. A tie plate extends across the bottom flanges of the center sills beneath the draft lugs to reduce the spread- ing tendency of the sills from the eccentric loading upon the lugs. Dummy couplers with flat buffing faces were used in these tests, these being duplicates in every re- spect of those used in test No. 3. The full buffing force was delivered as before, through the steel block to the rear stops. The cars were given tests at successive speeds of 4, 5, 6, 8, 10, 12 and 14 miles per hour. At 6 M.P.H. the dummy couplers began to scale at the key slots, and scaling and deformation at this point continued throughout the tests. At 8 M.P.H. the op- posing ends of the cars were bulged. At 10 M.P.H. the body bolsters were bent slightly. At 5 M.P.H. the rear lugs had slipped Yg in. on the sills and the stop faces had begun to deform. At 6 M.P.H. the lugs had bent and pulled away from the center sills % in. and the draft gear pockets had elongated ■£$ in. This bending and defor- mation of the draft lugs increased as the test proceeded, and at the 14 M.P.H. run both of the lugs of car A, and also the bolster center casting, were sheared off and driven back between the sills; the truck center pin also sheared off. From this failure the dummy coupler of car A was also driven back, bending the carrier iron and carrier iron bolt, and breaking the striking casting. The coupler key was bent and the front draft lugs broken away, the key being driven back through the webs 280 Draft Gear Tests of the U. S. Railroad Administration of the center sills for 3y 2 in. On car B one of the rear draft lugs broke at the 12 M.P.H. run, but these lugs were not sheared off, although they slipped on the rivets % in. each. At 8 M.P.H. the rear followers had bent 14 in. each, bending the draft lug faces also and slightly deforming the webs of the center sills. At the conclusion of the tests the follow- ing conditions were found: Condition of Cars The drop ends at the opposing ends of the cars were bulged, that of car A being bulged 3 in. at the top and 2% in. at the bottom. In car B this bulging amounted to 4 in. at the top and 1% in. at the bottom. The corner posts were bent as in test No. 3, as well as the upstanding legs of the end sill angles. The ends of the bolsters were bent downward % in. in car A and •(§ in. in car B. The sills were slightly bent in front of the bolster, the effect being as though the center of the bolster was forced upward. On car A the bolster center cast- ing was driven back and on car B it had slipped y 8 in. on the rivets. The end sills were not bowed downward, but were bowed inward an average of % in. The center sills were pushed through the cars an average of -f-Q in., the diagonal braces being in bet- ter condition than in test No. 3, although they showed evidence of failure and loose rivets. The floor boards shifted as in the previous test and the floor clips loosened. The center sills of car B were buckled % in. at the bottom flange near the rear draft lugs, those of car A being buckled % in. -The sills were spread an average of ^ in. at the rear draft lugs. The bending of the body bolsters reduced the total side bearing clearance of each of the trucks at the opposing ends of the cars by ■£$ in. During the test the draft gear pocket of car B was elongated % in. and that of car A was entirely destroyed. Condition of Coupler and Attachments Dummy Couplers, cast steel — Shanks bent both vertically and laterally, and upset and deformed at key slots. Short- ened an average of % in. each. Front Draft Lugs — Destroyed in car A. Not injured in car B. Rear Draft Lugs — Destroyed in both cars. Cast Steel Yokes — Not injured. (Note — These yokes do not come into action in buffing.) Coupler Keys — Badly bent in car A; re- quired to be burnt out. Not injured in car B. Front Followers — Not injured. Rear Followers — Bent % in. in car B. Badly bent in car A. Can be repaired. Bolster Center Casting — On car B slip- ped y 8 in. on rivets. On car A sheared off and bent. Can be straightened and reap- plied. Truck Center Pin — Sheared off. Cannot be used. Striking Plate — Broken. Can be used. Carrier Iron — Bent. Can be used. Carrier Iron Bolt — Bent. Cannot be used. In test No. 4 the greatest injury was to the draft gear attachments, the majority of parts requiring removal and renewal. Both cars were in bad order after the tests. The damage to the attachments was greater for car A than for car B, while the car damage was probably greater for car B. The rear lugs of this form of attachment having begun to deform at 5 M.P.H. and to actually bend away from the sills at 6 M.P.H., the greatest critical speed that can be set for them is 6 M.P.H., or a relative value of 36, as compared with 64 for the Farlow attachments used in test No. 3. In basing relative values upon the square of the speeds, it should be remembered that the energy is proportional to the square of the speed, or, in other words, that a car Draft Gear Tests of the U. S. Railroad Administration 281 moving at ten miles per hour will roll four times as far as one moving at five miles per hour. An experienced car rider has an in- stinctive knowledge of this fact in its rela- tion to the kinetic energy of the car, as exhibited by the force with which he ap- plied the brakes under varying speeds. In these tests, as in tests Nos. 1 and 2, it is unquestionable that a repetition of im- pacts at lower speeds would have produced failure, but, as before, it is believed the results obtained in these tests represent the comparative value of the two forms of at- tachments, namely, that the Farlow attach- ments as tested showed approximately twice the buffing value of the cast steel yoke and lug attachments: From the results of the test it is apparent : 1. That the buffing force should be dis- tributed to the car sills through a back stop casting bridging between the sills, rather than upon independent draft lugs riveted to each sill. 2. That if the draft gear is to be pro- tected by allowing a front key to strike, there should be substantial members on the sills for stopping the key. 3. That in car construction it is neces- sary to. give consideration to the results of impact when designing the body bolster for vertical loads. 4. That it is important properly to anchor the car floor and superstructure to the center sills in order properly to impart motion to the lading from the center sills. 5. That in cars with wood floors, or open type floors such as hopper cars, particular attention should be given to the diagonal braces in order that the car sides and center sills may be held from independent move- ment. \ : .^ J <. 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