fe w ^* ^ ^ °o«W*° a* v< V J .W; ^°^ * A ■*.,., v^ =iW» a>.* ^ ' 4 ^ G , °* *••»• ^ <>y&\ : 'a** Vw ,/\ W. /\ w / \ w . A . •li' a?*v ^1 «-°^ -• » "^ O X ' .0'' '^ *»,-.• AV a5°^ <. •'TVS •' .6** %. •'» - • * A * t . t,a * *b a> V «•""• -a 6 V "oV" ^ * * A C° * ■ ,*> 6 o « o ^ <6 r o V ^o* Ku Q \ o5°^ ^ 'Hi' v^» 'b^ ^■^ «5°^ - V. ° « ° A. w c. .f>~ . » • ^^ ^^' 4.^ « l1* • , ^°^ *b^ - -of aP »i'^* ^ v t * /r .^V/k- ^. a* *^ Wv • ^* & % ^ 6 V «& ^ A* '*.'i^- °o .,**.. i^l-X 4 ..^fc.% >*\«JK>**. d»*..ii&.% ,**•«*-' *f -of ^o*. »+■•-.' / v^->* °^ % ^/ v*^^\^ • \./ .-issfeji **^ .-afe\ \/ .-issfei-. **^ .-aBi\ v *°^ A • 4 .-^>>, ^.c^:.*°o **..•&!.%. /.c^.% Bureau of Mines Information Circular/1988 Surface Testing and Evaluation of the Hopper- Feeder- Bolter By Robert J. Evans, William D. Mayercheck, and Joseph L. Saliunas UNITED STATES DEPARTMENT OF THE INTERIOR , ; ,y WCw .^MA^iU^^ Information Circular 9171 iv A Surface Testing and Evaluation of the Hopper-Feeder-Bolter By Robert J. Evans, William D. Mayercheck, and Joseph L. Saliunas UNITED STATES DEPARTMENT OF THE INTERIOR Donald Paul Hodel, Secretary BUREAU OF MINES David S. Brown, Acting Director -fVlB* Library of Congress Cataloging in Publication Data: Evans, Robert J. Surface testing and evaluation of the hopper-feeder-bolter. (Information circular / United States Department of the Interior, Bureau of Mines ; 9171 ) Bibliography. Supt. of Docs, no.: I 28.27: 9171. 1. Coal-mining machinery— Testing. I. Mayercheck, William D. II. Saliunas, Joseph L. III. Title. IV. Title: Hopper-feeder-bolter. V. Series: Information circular (United States. Bureau of Mines) ; 9 1 7 1 . TN295.U4 622 s [622 '.334 '028] 87-600300 CONTENTS Page Abstract 1 Introduction 2 Description of the HFB 3 Power and control 4 Chassis 6 Bolter module 6 Surface testing 8 Test-program overview 8 Initial checkout 8 Maneuverability 8 Roof-bolter evaluation 9 Place change with roof bolting 11 Place-change time study 13 Rock breaking 14 Tail-boom lifting 16 Coal conveying 16 Dust-collector evaluation 19 Drawbar pull 20 TRS load measurement 21 Noise survey 23 Li ght survey 25 Shuttle-car loading trial 26 Surface test summary 27 Repairs and modifications 29 Mining plans 29 HFB with two-pass continuous miner 29 Bolter-module hazard analyses 33 HFB with continuous haulage 34 Conclusions 35 Appendix A. — HFB deployment 36 Appendix B. — HFB modification summary 37 Appendix C. — HFB repair summary 39 ILLUSTRATIONS 1. HFB overall view * 3 2. Bolter module 3 3. General arrangement of the HFB 4 4. Radio remote control 6 5. HFB outby end view 7 6. Bolting in the MBTS 9 7. Bolter-module stability trial 11 8. Rock-breaking trials 15 9. Breaker-motor's power consumption 15 10. Tail-boom lifting trials 16 11. Coal-conveying trial configuration 17 12. Relocated dust boxes 19 13. Drawbar pull test 21 14. TRS cylinder cross section 22 15. TRS load measurement test configuration 22 16. Typical sound-level data sheet 24 17. Right- and left-side passby noise spectrum 25 18. Top incident light measurements for the hopper feeder 26 11 ILLUSTRATIONS— Continued Page 19. Top incident light measurements for the bolter 26 20. Incident light measurements for the bolter sides 26 21. Incident light measurements for the bolter front and rear 26 22. HFB shuttle-car loading trial 28 23. Spillage during loading trial 28 24. Face-equipment configuration for 10-ft cuts 29 25. Mining plan for 20-ft cuts 31 26. Bolter module positioned for LH miner cut 32 27. Bolter module positioned for RH miner cut 32 28. HFB operator's areas 33 29. Hopper feeder 34 30. Hopper feeder used with MBC 35 31. Hopper feeder MBC interface 35 32. HFB with continuous haulage 35 A-l. HFB deployment 36 TABLES 1. HFB specifications 5 2. Roof-bolter time-study data 10 3. Detailed description of HFB operations 12 4. Place change with roof-bolting time-study summary, minutes and seconds... 13 5. Coal-conveying trial summary 17 6. Coal-conveying trial breakdown log 18 7. Dust-collector airflow measurements 20 8. TRS load-test summary 23 9 . HFB mining rates 30 UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT dc direct current in 3 cubic inch dB decibel in/s inch per second dBA decibel, A-weighted kHz kilohertz °F degree Fahrenheit kW kilowatt fc f ootcandle lb pound fL f ootlambert lb/ft 3 pound per cubic foot ft foot m meter ft 3 cubic foot min minute ft 3 /min cubic foot per minute pet percent ft* lb foot per pound psi pound per square inch ff lbf foot pound (force) r/min revolution per minute f t/min foot per minute s second gal gallon St short ton h hour st/min short ton per minute hp horsepower V ac volt, alternating current Hz hertz V dc volt, direct current in inch SURFACE TESTING AND EVALUATION OF THE HOPPER-FEEDER-BOLTER By Robert J. Evans, 1 William D. Mayercheck, 2 and Joseph L. Saliunas 3 ABSTRACT The Hopper-Feeder-Bolter (HFB) is a prototype multifunctional machine designed to improve productivity by minimizing continuous miner place changes. It is designed primarily to work beside a two-pass continuous miner, bolting on one side and then place changing to bolt the other side while simultaneously providing a surge car and lump breaker located directly behind the continuous miner. Surface testing was conducted at the Bureau of Mines Mine Equipment Test Facility (METF) to evaluate overall system performance and relia- bility. Tests were conducted to evaluate place changing, tramming, lump breaking, roof bolting, drawbar pull, conveying, temporary roof-support (TRS) capacity, lighting, and noise. Surface test results indicate the HFB is ready to be tested and evaluated underground in a production mode. Civil engineer, Pittsburgh Research Center, Bureau of Mines, Pittsburgh, PA. ■^Supervisory physical scientist, Pittsburgh Research Center. ^Project engineer, Boeing Services International, Pittsburgh, PA. INTRODUCTION The HFB is a prototype multifunctional mining machine that was conceived by the Bureau of Mines and designed and fabri- cated by the Engineered System and Devel- opment Corporation under a Bureau con- tract. This machine combines functions typically performed by a roof bolter and a feeder-breaker. It addresses a variety of problems that limit productivity of room-and-pillar mining systems: The maximum instantaneous output of a continuous miner is typically greater than the instantaneous haulage rate of the outby continuous haulage system. The HFB provides compatible surge capacity for the continuous miner output and levels out the coal-rock input for the continuous haulage system. Production delays occur when large pieces of coal or rock must be broken manually before being transported through a continuous haulage system. The HFB provides an onboard lump breaker. Production time is lost when a continu- ous miner and roof bolter place change. Because the HFB can bolt beside the con- tinuous miner, the number of entry-to- entry place changes is decreased; entry- to-entry place changes are replaced with side-to-side equipment changes in place. A continuous mining system using the HFB has some of the productivity advantages of a miner-bolter without the high capi- tal costs. The HFB can be used in various min- ing plans with several face equipment schemes. It can be used with or without the optional bolter module, and it can load into a continuous or intermittent (shuttle-car) haulage system. Scott, F. E. New Technology Improves Roof Control Safety. Coal Mining, v. 22, No. 8, Aug. 1985, pp. 24-28. Chironis, N. P. Bureau Continues to Pour Out Useful Medley of Machines and Ideas. Coal Age, v. 21, No. 2, Feb. 1986, pp. 22-35. Because of the many novel features of the HFB, an extensive surface test eval- uation program was conducted at the Bureau's METF prior to an in-mine trial. The objectives of the surface testing and evaluation program were 1. To "shake down" the HFB and improve performance and reliability based upon observations made under simulated under- ground conditions; 2. To measure HFB performance criteria so that underground performance and oper- ating requirements could be predicted; 3. To determine if the HFB meets its design criteria and is worthy of an in-mine trial; and 4. To prepare the HFB for an in-mine trial, including electrical approval by the Mine Safety and Health Administration (MSHA). The principal advantages of surface testing prior to an in-mine trial are that equipment performance can be proven and improved upon without interfering with production at an operating mine; this is absolutely paramount with face equipment such as the HFB. Even though the HFB has potential advantages, most mines would not risk the installation and operation of unproven face equipment, since any failure would be expensive in terms of operating cost and lost produc- tion. Because of this risk, there is a strong tendency in the mining industry to resist the introduction of novel mining systems or to reject very promising sys- tems after a short term if the in-mine trial does not meet anticipated results. Even though the most rigorous surface test and evaluation program will not sub- ject equipment to all of the harsh con- ditions found in the underground mines, a surface test program significantly increases the probability that problems related to major design deficiencies will be eliminated prior to the initial under- ground trial. DESCRIPTION OF THE HFB The HFB (fig. 1) consists of a crawler- connected to the chassis by a telescoping mounted chassis and a crawler -mounted boom. The chassis has the capacity to bolter-module assembly (fig. 2) that is level out miner coal-rock surges from 12 FIGURE 1.— HFB overall view. FIGURE 2.— Bolter module. to 7 st/min. An onboard lump breaker crushes against a universal chain convey- or. The conveyor on the outby end has a 45° heavy-duty swing tail that transports coal to the next stage of haulage. The bolter is connected to the HFB chassis by a telescoping boom and contains two mast- type bolter assemblies. Specifications for the HFB are presented in table 1. Figure 3 shows the components of the HFB. POWER AND CONTROL The HFB requires three-phase 460-V ac power, which runs four electric motors: a 75-hp 460-V ac motor for the lump breaker; two 21-hp 220-V dc motors for tramming; and a 160-hp, 460-V ac motor to drive a single variable-displacement hy- draulic pump and four fixed-displacement hydraulic pumps. The direct-current (dc) tram motors of the HFB chassis are con- trolled by a solid-state control system using silicon-controlled rectifiers (SCR) to convert the alternating current (ac) to dc power. Use of SCR's also permits variable speed control of the tram motors, allowing a tram speed of to 90 ft/min. Hydraulic power is used for all functions other than breaker operation and tramming the main HFB chassis. A 100-gal-capacity hydraulic reservoir is located on the right side of the main chassis. Dust-suppression water can be circulated through the hydraulic reser- voir heat exchanger to cool the oil. Electrical control components are located in a single, explosion-proof control box located on the left side of the chassis. Intrinsically safe solenoid valves con- trol all hydraulic actuators except the bolting functions and conveyor drive. Five emergency-stop ribbon switches are located on the chassis and four are located on the bolter module. Optionol bolter-module assembly Boom traverse ^Main control panel drive motor Pump motor / ^Hydraulic reservoir Secondary dust-collector r " box and vacuum Dumo /~ ^ onve y° r motor 2-drill-head roof bolter motor Conveyor elevation cylinders Crossover PLAN Breaker motor TRS cylinders ->sz Breaker speed reducer maximum extension ELEVATION FIGURE 3.— General arrangement of the HFB. Not to scale TABLE 1. - HFB specifications HFB 48 ft, 8 in long with fully extended boom. 54-in minimum working heights. Chassis 460-V ac power. 4 ft high; 9 ft, 7 in wide; 26 ft, 9 in long. Weight - 49,500 lb. '" Mounted on 2 16- by 84-in crawler tracks. 2 tram motors at 21 hp, 220 V dc. Tram motors SCR controlled for to 90 ft/min tram speed. 1 breaker motor at 75 hp, 460 V ac. 1 pump motor at 100 hp , 460 V ac. 191-ft -capacity hopper. 30 in wide, variable speed and direction, center-strand chain conveyor. Variable elevation tail boom. Variable swing tail boom (45° to the left and right of centerline) . Radio remote control. Bolter module Hydraulic and intrinsically safe power provided by chassis. Height varies from 4 ft (TRS retracted) to 8 ft (TRS fully extended) . 5-ft, 5-in boom extension capability. Weight - 7,000 lb. Mounted on a single, 11- by 36-in crawler track. TRS exerts loads of 12,000 lb at 500 psi. 2 drill heads on 4-ft spacing. Drill torque adjustable to 275 fflbf at 2,000 psi. Drill speed adjustable to 325 r/min. Drill thrust adjustable to 7,000 lb. 3-stage vacuum dust-collection system. Safety 9 emergency stop switches (5 on the chassis, 4 on the bolter module). Fire-suppression water sprays. Dust-suppression water sprays. Components Undercarriage and tram motors from Joy 14 BU loader. Reliance pump and breaker motors. FMC solid-state tram control system. Faulk breaker speed reducer. Fletcher drill boxes. Donaldson dust-collection system. Joy conveyor chain. Eaton and commercial shearing pumps. McJunkin lights. The HFB chassis can be operated from two locations: the control panel on the machine, and the remote control. The main control panel, consisting of a sin- gle row of toggle switches, located on the right side of the HFB, can be used to operate all functions except roof bolting. The remote-control unit (fig. 4) can be used to operate all major HFB functions except bolting. The frequency modulation (FM), a radio remote con- trol, is powered by a specially modified 12-V dc cap-lamp battery. A radio re- ceiver is located in the controller box. Bolter-module controls are located on the inby edge of the bolter-module's bolt tray. CHASSIS The main HFB chassis is mounted on two crawler tracks: each crawler is 16 in wide by 84 in long. A 30-in-wide center- strand chain conveyor runs the full length of the HFB chassis (fig. 5). A 4-3/4-st-capacity surge hopper is located on the front portion of the chassis. The chain conveyor is powered by a variable- displacement hydraulic motor located on the conveyor tail boom, which permits variable conveyor speed from to 200 ft/min in both directions. The conveyor speed can be controlled in manual and automatic (anti-stall) modes. A hand- operated lever is used for manual speed and direction control. An anti-stall switch is used to automatically control the conveyor speed. In the automatic anti-install mode, the conveyor speed is decreased when the breaker motor draws large amounts of current. The conveyor tail boom can pivot 42 in. in both direc- tions from the chassis centerline. It has elevating cylinders and was designed to support and position the inby end of the continuous haulage system. The coal-rock lump breaker is located in the center of the HFB chassis over the chain conveyor. It consists of rows of carbide-tipped conical bits mounted on a shaft that rotates at 90 r/min. A double-strand roller chain connects the breaker shaft to a gear speed reducer driven by the 75-hp breaker motor. FIGURE 4.— Radio remote control. Six 480-V ac sodium vapor lamps are located on the HFB chassis. A single, intrinsically safe fluorescent lamp is located on the inby end of the bolter module. BOLTER MODULE The bolter module is connected to the HFB chassis by means of a nonpowered telescoping boom. The bolter module con- tains two mast-type bolter assemblies on each side of the machine, two sets of bolter operator controls, two TRS cyl- inders, two primary dust-collector boxes, and a single, hydraulically driven 11- in-wide by 36-in-long crawler track. A rotary actuator, located between the operator controls, is capable of rotating the entire bolter module about the end of the telescoping boom. A gooseneck in the boom, directly behind the bolter module, FIGURE 5.— HFB outby end view. enables bolter operators to cross over the boom. A single tilt cylinder, lo- cated between the bolter module and the boom assembly, controls the sideways tilt of the bolter module. The telescoping boom is 7 ft, 7 in long when retracted and is capable of extending to 13 ft. The boom is attached to the HFB chas- sis by a movable sliding bracket, which allows the end of the boom to be located at different positions along the inby end of the chassis. SURFACE TESTING TEST-PROGRAM OVERVIEW Surface tests were divided into sequences that evaluate a particular sub- system or machine function to verify and measure the performance of the HFB. Numerous modifications were made to the HFB during the test program to cor- rect deficiencies noted during surface testing. Important test sequences were recorded on videotapes that are available at the Pittsburgh Research Center (PRC). INITIAL CHECKOUT The assembled HFB was delivered to the METF on April 19, 1983. All safety devices and functions were checked for proper operation, and several minor repairs, adjustments, and modifications were made; all function rates were mea- sured at or close to specifications. MANEUVERABILITY This first test sequence was conducted to measure the HFB tram rate on a dirt floor, along with evaluation of the radio-control capability to determine if the HFB could tram with the bolter module in the extended position. Time-measured trials were made for the HFB to tram through a 48-ft-long entry, turn through a 90° intersection, and tram through a 48-ft-long crosscut (110 ft total). The entry and crosscuts were both 20 ft wide with 90° square corners. The HFB operator, using the handheld, remote-control unit was able to position himself for optimum safety and visibility during the trials. A single cablehandler was used when required. For the first set of maneuverability tests, a pin was installed into the telescoping boom so that the boom length was kept constant at 7-1/2 ft. For the second set of maneuverability tests, the pin was removed from the boom so that the boom was free to telescope between 7-1/2 and 13 ft. Four trials were conducted for each of the two configurations. The average tram time required for both tram- ming configurations (fixed or variable boom length) was 1 min, 25 s; therefore, neither tramming configuration was supe- rior. The average tram speed during these trials was 77 ft/min, which is less than the specified 90 ft/min tram speed; this is attributed to the slower tram rate during the turn into the crosscut and can be compared with the average con- tinuous miner place-change tram speed of 35 ft/min. Maneuverability trials were attempted with the bolter module in the stored position on the HFB. For these trials, the pin in the sliding bracket was removed and the tram drive of the bolter module was used to push the telescoping boom through the sliding bracket and into the hopper of the stationary HFB. The boom hold-down bracket was lowered onto the boom in an attempt to pick the bolter module off the ground; however, the bolter module was too heavy. When this was tried, the rear portion of the main chassis crawler tracks came off the ground. The hold-down bracket was sub- sequently removed from the HFB, since it did not function properly and tramming trials showed that it was not required. The HFB was originally equipped with a hold-down bracket that could store the bolter module clear of the ground. The handheld remote-control unit, which allows the operator to be in a safe position, proved easy to use enabling operators to quickly become adept in maneuvering the HFB. ROOF-BOLTER EVALUATION Roof-drilling trials were conducted to verify proper performance of the bolting system. The drilling-rate parameters for both bolter units were the drill cylinder thrust relief valve was set at 1,000 psi; the drill motor's torque relief valve was set at 1,850 psi; the unloaded drill rotation rate was set at the maximum rate of 1,850 r/min; the unloaded drilling thrust rate was set at 1 in/s. The miner bolter test structure (MBTS) was utilized to support two simulated roof blocks that were used during the roof-bolting trials. The bottom of the roof blocks were 6 ft above ground, and each roof block was 4 ft wide by 6 ft long by 6 ft high. The blocks were constructed from a concrete mixture of 50 pet crushed limestone (3/4-in by 0), 30 pet coarse sand, and 20 pet portland cement. The average compressive strength of four cylinder samples after 28 days was 5,100 psi. Mechanical expansion shell roof bolts, 42-in long and 5/8-in diam, were used during the bolter evaluation; 4-in roof plates were used instead of 6-in roof plates in order to save roof block space. A single, 48-in-long starter steel with 1-1/8-in-square end was used to drill all holes. Carbide-tipped drill bits were used to drill 1-3/8-in-diam holes. Both 36- and 24-in-long drill steel wrenches were used to tighten the roof bolts. A stopwatch was used to continuously record the starting and stopping times for each drill unit. For 44 trials, a 24-in-deep by 1-3/8-in-diam hole was drilled. The vacuum dust-collection boxes located on the bolter module were emptied as required during these tests, and the hydraulic tank temperature was recorded when the dust boxes were emp- tied. Figure 6 shows the HFB bolting into the MBTS roof blocks. Table 2 shows the results of the roof- drilling trials. For 48 ft of drilling, the left bolter had an average drilling rate of 2 ft in 56 s (2.14 ft/min); for *-:!^ FIGURE 6.— Bolting in the MBTS. 10 TABLE 2. - Roof-bolter time-study data, minutes and seconds Left bolter Right bolter Oil Test Start Stop Elapsed time Start Stop Elasped time temp , °F 1 2 1:15 3:48 6:45 8:52 32:37 34:55 NA 45:56 NA 0:00 2:35 5:20 7:16 9:32 13:16 15:05 16:37 0:00 2:49 4:42 8:15 12:24 0:00 1:57 6:01 7:52 2:05 4:37 7:32 9:37 33:19 35:36 NA 46:41 NA 1:20 3:42 6:16 8:05 10:24 14:02 15:50 17:25 1:19 4:03 5:53 9:18 13:14 1:10 3:00 6:51 8:42 0:50 0:49 0:47 0:45 0:42 0:41 NA 0:45 NA 1:20 1:07 0:56 0:49 0:52 0:46 0:43 0:48 1:19 1:14 1:11 1:03 1:10 1:10 1:03 0:50 0:50 1:27 3:40 NA 8:44 32:42 35:00 38:45 46:02 48:28 2:06 5:09 6:58 NA 12:55 NA 16:30 19:25 NA 2:49 4:42 8:27 12:24 0:06 4:06 6:01 7:52 2:15 4:25 NA 9:29 33:30 35:50 39:32 46:48 49:16 2:58 6:02 7:49 NA 13:42 NA 17:20 20:23 NA 3:44 5:42 9:11 13:05 0:47 4:48 6:44 8:35 0:48 0:45 NA 0:45 0:48 0:50 0:47 0:46 0:48 0:52 0:53 0:51 NA 0:47 NA 0:50 0:58 NA 0:55 1:00 0:44 0:41 0:41 0:42 0:43 0:43 90° NA 3 NA 4 115° 5 6 95° ( 1 ) 7 ( 2 ) NA 8 9 10 115° 60° 11 12 13 14 NA NA NA NA 15 16 17 18 NA NA 125° 80° 19 20 21 22 23 NA NA ( 2 ) 110° 90° 24 25 NA NA 26 115° NAp NAp 0:56 NAp NAp 0:48 NAp NA Not available. NAp Not applicable. '10/1 2 -Re pi 3 tests. ace right bit. NOTE. —Drill depth was 2 ft. 44 ft of drilling, the right bolter had an average rate of 2 ft in 48 s (2.5 ft/ min). The difference in the drilling rates was assumed to be caused by small changes in the drilling parameters, such as relief-valve settings and flow rates between the left and right modules. The faster drilling rate observed for the right bolter also resulted in a higher bit failure rate. The carbide-tipped bit had to be replaced twice for the right bolter because of carbide chipping; whereas, the left bolter used the same bit for all trials. As the hydraulic oil temperature increased, both right and left bolters showed an increased drilling rate. Table 2 also shows when the dust boxes were emptied. In most cases, they were emptied because of test startup conve- nience, except in the third sequence when the dust collectors were full. Each of the two primary dust-collection boxes on the bolter module had a volume of 680 in 3 , for a total volume of 1,360 in . The secondary dust-collection box and final filter were located on the HFB chassis approximately 35 ft away from the primary boxes; therefore, most cuttings were deposited in the two primary boxes. The exact number of feet to be drilled before emptying the primary dust boxes would depend on the swell factor of the 11 roof material being drilled. During the bolting trials, 24-in-deep by 1-3/8-in- diam holes were drilled for a total vol- ume of 35.6 in of in situ rock per hole. Up to 14 of the 24-in-deep holes were drilled without emptying the primary boxes, for a total volume of 500 in of in situ rock. The primary dust boxes were filled after the 14 holes were drilled, so the capacity of the primary boxes was approximately 28 lineal ft if a 1-3/8-in-diam bit was used. The bolter module was easily posi- tioned at the desired location by using toggle-switch-controlled solenoid valves. Instability of the bolter module was observed while tramming on uneven bottom conditions (fig. 7). Use of the bolter roll cylinder allowed the bolter module to stabilize prior to drilling. PLACE CHANGE WITH ROOF BOLTING Time studies utilizing place changes with roof bolting were conducted to study person-machine configurations and to gather time-study data. Time studies also provide mining-rate data for mine operators so that they can predict min- ing rates for their own operation. For these studies, the HFB chassis was located in the center of the 20-ft-wide entry formed by the MBTS. A Jeffrey 101 two-pass continuous miner was located inby of the HFB at one side of the entry. The HFB bolter module was located at the other side of the entry beside the con- tinuous miner. The movable roof cart of the MBTS was initially centered 10 ft behind the cutterhead of the continu- ous miner. During the trials, both HFB FIGURE 7.— Bolter-module stability trial. 12 bolter operators were able to drill and Drill and install two roof bolts; insert roof bolts into the roof blocks contained by the movable roof cart (fig. Tram the HFB chassis and bolter module 6). After several practice sessions, outby of the continuous miner; four HFB continuous-time studies were conducted with the following sequence, Switch the bolter module from one side which simulated a 12-ft face advance: of the entry to the other; and, Drill and install two roof bolts; Tram the HFB chassis and bolter module inby and repeat. Advance the bolter module 4 ft using local control; Definitions for the time-study events are given in table 3. Several sequences Drill and install two roof bolts; were videotaped for further analysis in the place-change time study. Advance the bolter module and HFB chas- sis 4 ft using local and remote controls; TABLE 3. - Detailed description of HFB operations Drill and bolt: Start First HFB operator starts drilling. Event Enough time for both inside and outside HFB drill opera- tors to each drill a 43-in deep by 1-3/8-in-diam hole using a two-piece drill steel and insert and torque a 42-in-long point anchor mechanical roof bolt. Stop Last HFB operator stops torquing roof bolt. Advance bolter module: Start Last HFB operator stops torquing roof bolt. Event Enough time to lower the TRS; advance the bolter module 4 ft from local position, position the bolter module, and set the TRS. Stop First HFB operator starts drilling. Advance bolter and chassis: Start Last HFB operator stops torquing roof bolt. Event Enough time to lower the TRS, advance the HFB chassis 8 ft using the remote control, position the bolter module, and set the TRS. Stop First HFB operator starts drilling. Place change: Start Last HFB operator stops torquing roof bolt. Event Enough time to lower the TRS, tram the bolter module outby of the miner, switch bolter-module boom to the opposite side, empty the dust box, tram the HFB inby to behind the miner, position the bolter module, and set the TRS. Stop Stop when TRS is set. 13 Four operating personnel were used dur- ing these tests: a miner operator, a miner helper, an "inside" bolter opera- tor, and an "outside" bolter operator. In addition, a roof-cart operator was used to advance the roof-cart position by 4-ft increments to obtain a realistic advancing bolt pattern. The continuous miner was also advanced with the roof cart, so the cutterhead of the miner was always 10 ft in front of the bolter- module drill centerline. Both the miner and HFB power cables for these trials were located along the right side of the MBTS. When the miner was on the left side of the entry and the bolter module was on the right side, the miner power cable was tied to the mine roof (roof cart) with wire ties. The roof-bolter operators used a two- piece drill steel with 1-3/8-in-diam carbide-tipped bits. For all holes, the operators set the TRS , drilled 43-in- deep holes, inserted a 42-in-long point anchor mechanical roof bolt, torqued the bolt to 150 ff lb, and lowered the TRS. A 24-ft total face advance was sim- ulated by drilling and inserting 24 roof bolts in a 4- by 4-ft bolt center pattern, as the HFB bolted beside and exchanged positions "in place" with a two-pass continuous miner. A 12-ft advance was made by the miner before changing positions with the bolter mod- ule. Table 4 is a summary of the time- study results. The time-study events were broken down into elements that could be recombined into different combinations to simulate different cut plans. Twelve "drill-and-bolt" events were timed for an average value of 3 min, 12 s. The drill-and-bolt times will change from mine to mine, depending on the type and length of bolts used and the drilling rate. The average time deter- mined for these trials is valid only for these unique drilling conditions. Four "advance-bolter-module" events were timed for an average of 1 min, 43 s. Four "advance-bolt er-module-and-chass is" events were timed for an average of 2 min, 44 s. Further place-change trials indicated that this event would not be part of the normal mining sequence, since the miner helper needs to continuously advance the HFB's chassis during bolting to keep the HFB's hopper under the miner tail boom. The bolter operators, there- fore, do not need to advance the HFB as a separate operation. Three place-change events were timed for an average value of 5 min, 21 s. This value was decreased in subsequent place-change time-study tri- als, after an improved person-machine movement scheme was used. PLACE-CHANGE TIME STUDY Based upon an analysis of the videotape from early place-change trials, a person- machine movement plan for a face area change was established. This plan, shown in appendix A, was used for six trials to accurately determine the time required for the HFB bolter module to exchange places in a 20-ft-wide entry with a two- pass continuous miner. Four operating personnel were used: a miner operator, TABLE 4. - Place change with roof -bolting time-study summary, minutes and seconds Event Trial 1, 1 8/23 Trial 2, 2 8/23 Trial 3, ' 8/23 Trial 4, ' 9/7 Average 3:21 1:59 2:40 1:55 3:00 4:45 3:04 1:51 2:58 3:07 3:20 5:05 2:37 2:00 2:15 4:05 4:27 NA 3:07 1:01 3:56 1:50 3:37 6:12 3:02 1:43 2:57 2:44 3:36 5:21 17:40 19:25 NAp 19:43 19:23 NA Not available. NAp Not applicable. Bolter module on right, 2 Bolter module on left. 14 a miner helper, the inside bolt operator, and the outside bolter operator. During the time study, time was started when the bolter module TRS lost contact with the roof during lowering. Time was stopped when the TRS was set against the roof after the place change was completed. No face advance was made by the bolter mod- ule during these studies; the final posi- tion of the bolter module was the same distance as the initial position was inby into the entry. The average time required to have the bolter module exchange positions in the entry with the continuous miner was 2 min, 57 s for three right-to-left moves by the bolter module, and 3 min, 21 s for three left-to-right moves. The differ- ence in these times was attributed to the delay of hanging the miner cable during the left-to-right bolter-module move. The average time for both right-to-left and left-to-right moves was 3 min, 9 s. The sequence of person-machine movement for the place-change time-study trials is presented in appendix A. This sequence could be used for any intermittent outby haulage method, such as shuttle cars. A modification to this sequence would be required for use with a continuous outby haulage system. The sequence was de- signed to achieve the following objec- tives: (1) keep personnel from entering under unsupported roof; (2) keep person- nel from passing between moving equipment and the mine rib; (3) keep the bolter module at least 10 ft from the miner cut- terhead; and (4) keep the HFB hopper as close as possible to the miner discharge boom. ROCK BREAKING Rock-breaking trials were conducted to verify proper functioning of the breaker and to record the power consumption of the 75-hp breaker motor during rock- breaking operations. Rock samples used during the rock-breaking trial were competent limestone obtained from the Bureau's Lake Lynn Experimental Mine. The power consumption of the HFB was monitored utilizing a current transformer (C/T) with a ratio of 300:5 on the A and C phases of the HFB power cable. The C/T's, having a factory-stated accuracy of ±1 pet, were connected to a watt transducer that provided a 0- to 10-V dc output for a 0- to 240-kW power span. The watt transducers had a stated accu- racy of ±0.25 pet. Several different test sequences were conducted : During trial A, several small rocks (8- by 10- by 12-in; 8- by 18- by 8-in; and 6- by 16- by 10-in) were dropped together into the HFB hopper. The con- veyor motor was operated at full-speed, anti-stall mode and breaker motor power consumption was recorded during rock- breaking operations. During trial 5, a single 18- by 30- by 24-in boulder was dropped into the HFB hopper. The conveyor motor was operated at full-speed, manual mode, and the breaker motor power consumption was recorded. The conveyor speed was varied by the operator during this sequence. During trial C, a 24- by 16- by 18-in rock and a 12- by 12-in rock were dropped together into the HFB hopper. The con- veyor motor was operated at full-speed, anti-stall mode, and the breaker motor power consumption was recorded. The HFB successfully broke all rock specimens during the rock-breaking tri- als. The breaker contained two rows of three conical bits mounted on a 5-in- diam solid shaft (fig. 8). Power to the breaker was transmitted from a 75-hp electric drive motor through a speed- reducer and roller-chain drive. Figure 9 identifies plots of the breaker motor power consumption during the three rock- breaking trials. During trial A, the plus 6-in rocks were quickly fed through the breaker. The maximum observed power consumption was a peak of 32 kW. 15 :;:.. FIGURE 8.— Rock-breaking trials. 80 64 48 32 16 i i i i — i i i i — i — r~r- 1 — i — i— i — r —Start motor T . . . Trial A ~\ — n — n — r - r i liVJ i Finish breaking i 80 64 Q- § 32 o 16 t — |— i— i — i — i i i i i i i — i — r— n — n—i — i — i — |— i — n — m — i i i i — r Trial B Breaker tripped Reverse conveyor i i i i i i i i i i i i [ I .1 I JL.i .. I..I I ill-i.. > .. .1 I I I I l l l I I I I I I I I I I I I I i i i \. 80 64 48 32 16 -Start motor jyimJ-JjjJJiUl i i i i i i i — i i i i i Trial C —Finish breaking i i I i i i i i i i TIME, min - - FIGURE 9.— Breaker-motor's power consumption. During trial B, the bits gradually- chipped away at the face of a plus 18-in rock until the rock caught under the bits and the circuit breaker controlling the breaker motor tripped. The breaker was reset and the rock was eventually broken. During trial 5, the conveyor speed and direction were manually con- trolled, and for a portion of the tri- al, the rock was reversed away from the breaker. The power-consumption plot of trial B reflects this no-load condi- tion with a power draw were several instances when the power draw went off scale above 80 kW. During trial C, power consump- tion went off scale four times, but the two plus 12-in rocks were broken without difficulty. of 8 kW. There during trial B 16 A unique feature of the HFB is the current transformer connection to the breaker motor power lead. A high-current draw on the breaker motor was expected to decrease the speed on the conveyor when the anti-stall switch was actuated. How- ever, power-consumption data (fig. 9) shows that current draw was high only for short periods of time, and the anti-stall feature was not activated for breaking single rocks. Figure 9 shows breaker operation during the trial C. TAIL-BOOM LIFTING The HFB was designed with a tail boom that is more sturdy than booms on exist- ing continuous miners to enable the HFB to perform either as a tractor or to support the inby end of continuous haul- age systems. To verify the support capa- bility, an 8,000-lb weight was lifted by the tail boom of the HFB. The weight was made by suspending a number of steel plates from a chain sling. Lifting tri- als were conducted with the HFB tail boom on the centerline of the HFB chassis and with the tail boom at maximum left and right swing positions (45° to the left and right of centerline). The HFB tail boom successfully lifted and held an 8,000-lb weight that was suspended from the tail boom, as shown in figure 10. No problems were observed when the tail boom suspended the weight with boom swings to the maximum left and right. COAL CONVEYING Coal-conveying trials were held to verify the surge-handling capability of the HFB and performance of the HFB chain-conveyor system. Surge capacity is essential if the HFB is used with con- tinuous haulage systems. To enable con- tinued HFB conveyor operation, the HFB was arranged in a closed-loop coal-con- veying circuit, as shown in figure 11. The circuit consisted of the HFB with bolter module removed, a 50-ft belt con- veyor, the 12-unit multiple-unit conveyor haulage (MUCH) system, and a 30-ft belt conveyor. To measure the discharge from the HFB, a belt weigh scale was installed on the 50-ft belt conveyor, located immediately outby the HFB. The belt scale consisted of a speed sensor mounted on the belt tail pulley, a weigh bridge that provided FIGURE 10.— Tail-boom lifting trials. 17 FIGURE 11.— Coal-conveying trial configuration. an electric signal proportional to belt loading, and an electronic integrator and readout unit. Before commencing the coal-conveying trial, the belt scale was physically calibrated with calibration weigh chains. A strip-chart recorder was used to record the instantaneous belt- scale output during the coal-conveying trial. Recorder calibration was per- formed prior to each day's testing. At the beginning and end of each testing segment, the belt-scale totalizer dis- play was recorded to determine the total amount of coal transported. Testing commenced when a 1.5-yd -capac- ity front-end loader dumped coal into the HFB hopper, which discharged the coal onto the conveyor of the closed-loop sys- tem. The quick discharge of the front- end loader simulated surge loading by a continuous miner. Coal used during test- ing was wetted to control dust and con- sisted of a mixture of 2-1/2- by 2-in coal, 2- by 1-1/2-in coal, and run-of- mine coal from the Bureau's research mine. The coal was fed to the system until a system malfunction was detected. Table 5 is a summary of the discharge rate of the HFB over the entire trial. The maximum discharge rate was 6 st/min. Total operating time during the trial was 560.6 min. During the trial, a total of 682.1 st of coal was conveyed. The average discharge rate over the entire trial was 1.22 st/min, which was visually averaged from the chart recorder print- out for each run segment. During the test period, there were several HFB fail- ures: the main breaker tripped three times, the conveyor became jammed five times, and hydraulic failures occurred twice. Table 6 is a listing of HFB breakdowns during the trial. Since the coal being handled by the HFB during the trial was wetted to control dust, it is probable that the greater effort required to convey wetted coal increased hydraulic power requirements that contributed to all failures. Following the conveying trial, a cleanout hole was burned in the HFB chassis underneath the front conveyor idler to decrease the frequency of con- veyor jams; subsequent testing verified improved performance. TABLE 5. - Coal-co Average haulage nveying rate, trial T( summary sst time, st/min 1-2 min 197.0 244.2 3 65.0 4 23.9 5 29.0 1.5 560.6 18 TABLE 6. - Coal-conveying trial breakdown log Cumulative Average loading Date run time, min rate, st/min Description 3/14/84 18.0 2 Main breaker tripped out. Breaker was unable to be reset. Problem was diag- nosed as poor connection on source side of breaker. Connections were tightened, resolving the problem. 50.0 2 Main breaker tripped out. Reason unknown. Breaker was reset. 63.1 2 Power center tripped out. Reason unknown. Breaker was reset. 3/29/84 298.0 2 Main breaker tripped out. Problem was poor connection on load side of breaker. Breaker was overheated in that area. Connection was tightened, resolving the tripping problem. 3/30/84 341.0 4 Conveyor hydraulic motor hose failed. The crimp failed, allowing the hose to blow out end of fitting. The crimp-type, staple-lock fitting was replaced. 341.5 4 HFB was jammed. Wet coal overloaded the conveyor system. Hopper was emptied manually. 518.2 3 HFB was jammed. Ran conveyor back and forth to clear hopper. 4/06/84 525.7 3 HFB was jammed. Manually shoveled the system and ran conveyor back and forth to clear system. 531.7 4 HFB was jammed. Manually shoveled the system and ran conveyor back and forth to clear system. Intermediate vehicle 1 also stopped. Reason unknown. 4/09/84 552.2 6 Conveyor hydraulic motor hose blew out of crimp fitting. (This hose was on the opposite port to the hose, which failed on 3/30/84.) Hose was replaced. 4/12/82 554.2 4 HFB was jammed. Ran conveyor back and forth to clear system. 19 The HFB coal-conveying trials were con- ducted with a prototype continuous haul- age system, which limited the HFB evalu- ation. The HFB has a 4-3/4-st capacity hopper with a 28-in-wide by 8-in-deep variable speed conveyor that was designed to limit the discharge rate from the HFB to 6 st/min, even though the discharge rate of a continuous miner loading into the HFB may be much greater for short periods of time. During the trial, a 6-st/min discharge rate was achieved for only 1.5 min out of the 560.6 min total test time. Lack of operating time at 6 st/min is not due to a deficiency in the HFB, but rather to the performance of the HFB and MUCH coal-conveying test loop. It was observed that when the front-end loader discharged into the HFB hopper, the HFB did limit the discharge rate to below 6 st/min without spillage or clogging. DUST-COLLECTOR EVALUATION Initial examination of the HFB indi- cated that the primary dust-collector boxes were located in an undesirable location. The boxes, in their original position between the TRS cylinders on the bolter module, could only be opened by a person standing inby of the TRS. Various alternatives were evaluated, and a deci- sion was made to relocate the primary dust boxes midway on the bolter module boom (fig. 12). The original festooned method of sup- porting the hydraulic hoses and vacuum line was replaced with a takeup config- uration, and a larger bolt tray was installed. The modifications allowed proper functioning of the bolter mod- ule; tramming and steering capabilities were not affected. The bolter opera- tors believed that the increased bolt tray capacity would increase bolting efficiency. Airflow and vacuum pressures were mea- sured to evaluate the performance param- eters of the relocated dust-collection system. A vane anemometer was used to measure airflow in each drill head. The 4-in-diam anemometer was sealed in the end of a bell-type reducer fitting that terminated in a 1-1/8-in square fitting that was seated firmly in the drill head. A vacuum gauge rated at to 30 in of mercury, set in a 1-1/8-in square fit- ting, was used to measure vacuum pressure at the drill head. Prior to the airflow measurements, all dust-collector boxes were completely cleaned, and flow-control FIGURE 12.— Relocated dust boxes. 20 valves were opened. Airflow and vacuum pressures at the drill head were recorded under various operating conditions. Vac- uum pressures between the vacuum pump and the secondary collection box were also recorded under varying conditions. Results of the airflow measurements are presented in table 7. Although airflow values exceeded the minimum MSHA-recom- mended values, this was expected, since only the location of the primary dust- collection boxes and not the schematic diagram of the system was changed. Drilling trials were conducted to ver- ify the performance of the modified system. Observations and timings were recorded as the left and right drills were operated simultaneously and indepen- dently. All dust-collection boxes were thoroughly cleaned prior to drilling. One-piece, 48-in-long drill steels were used to drill 42-in-deep holes. Each steel was fitted with a 1-3/8-in-diam carbide drill bit. Holes were drilled into concrete roof blocks in the MBTS. Ten 42-in-deep, 1-3/8-in-diam holes were drilled before the dust-collection sys- tem became clogged (approximately 35 lineal ft of roof drilling). This is an increase over the 28 ft reported in the roof-bolting trials section of this report. The clog located in the dust hose immediately connected to the drill head was easily removed. The average drilling rate during these trials was 2.25 ft/min. The dust-collection system functioned properly during both indepen- dent and simultaneous drilling operations. DRAWBAR PULL A drawbar pull test was conducted to measure the drawbar pull of the HFB and to observe how the electronically con- trolled tram system would respond to an overload situation. Drawbar pull pro- vides a measure of the power available for towing and tramming up a grade. The drawbar pull of the HFB chassis (with the hopper empty) was measured by pulling against a dynamometer, which was anchored to a 35-st mobile crane, as shown in figure 13. The dynamometer was attached to the HFB chassis by a two-leg sling chain, which was attached to clev- ises mounted directly behind each HFB crawler. The crane parking brakes were used to prevent the crane from moving. A videotape camera and recorder were used to record the dynamometer dial reading and HFB drive sprocket motion as the HFB tried to pull the mobile crane. TABLE 7. - Dust-collector airflow measurements Condition Measurement Right chuck open Vacuum in blocked left chuck = 3.4/in Hg; airflow in left chuck = 25 ft 3 /min. Left chuck open Vacuum in blocked right chuck = 3.4/in Hg; airflow in right chuck = 25 ft 3 /min. Right chuck blocked Vacuum in blocked left chuck = 12.0/in Hg; airflow in left chuck = 40 ft 3 /min. Left chuck blocked Vacuum in blocked right chuck = 11.9/in Hg; airflow in right chuck = 41.5 ft/min. Both chucks blocked Vacuum at pump inlet = 12.5/in Hg. Both chucks open Vacuum at pump inlet = 8.0/in Hg. Right chuck blocked Vacuum at pump inlet = 8.9/in Hg. Left chuck blocked Vacuum at pump inlet = 9.0/in Hg. 21 FIGURE 13.— Drawbar pull test. Prior to the drawbar pull test, the weight of the HFB chassis was measured by freely suspending the chassis from a 50-st-capacity dynamometer, which was attached to the 35-st mobile crane. The observed weight of the HFB chassis was 49,500 lb. The mechanical dynamometer had a resolution of ±500 lb and a fac- tory-stated accuracy of 1/2 pet of full scale. The drawbar pull produced by the HFB on a dry fly ash-clay floor was measured between 25,000 and 38,000 lb. Readings were recorded from the dynamometer dial as the crawlers continuously slipped and jerked forward on the floor over several minutes. Ruts approximately 2 in deep were dug into the floor during this period. The videotape of the sprocket motion revealed that continuous torque was not maintained by the drive sprocket; sprocket relaxation during jerking and after a crawler slip was apparent. The relaxation was caused by the character- istics of the tram control system. A second test was conducted with the floor thoroughly wetted. The drawbar pull produced by the HFB was measured between 30,000 and 32,000 lb during crawler slippage. A dynamometer reading of 24,000 lb was recorded during slippage of the right crawler only. A dynamometer reading of 24,000 lb was also recorded during slippage of the left crawler only. No breaker tripping or erratic opera- tion was observed during the drawbar pull tests. The drawbar pull strength of the HFB is typical for a crawler-mounted vehicle the same weight as the HFB. TRS LOAD MEASUREMENT The objectives of this test were to measure the total load that the TRS sys- tem exerted against the mine roof and to verify proper performance of the TRS sub- system. The function of the TRS was to provide temporary roof support and opera- tor protection during roof bolting. The TRS on the HFB consisted of two, two- stage hydraulic cylinders. The roof end of each cylinder terminated in two arms, each with a plate for roof contact. The TRS cylinders received hydraulic power from a gear pump located on the HFB chas- sis. The main system relief valve pro- tecting the pump was set at 2,250 psi. The pressure to the TRS cylinders was protected by a relief valve located between the two TRS cylinders. The con- tractor recommended a maximum relief valve setting of 1,000 psi. Figure 14 is a diagram of the TRS hydraulic circuit. The test configuration is shown in fig- ure 15. Three 50,000-lb compression load cells were attached to the underside of the miner bolter test-structure roof cart. A 4- by 8- by 1-in steel plate was 22 positioned below the load cells. The HFB bolter module was positioned under the roof cart so that the raised TRS arms would hold the steel plate against the load cell's contact points. A 5,000-psi o m J 1 e TRS flow control Ur 1777777711 annular area-^ annular m2 area VlUlllIt I EZZZZZZ7T 3" L_J Maximum setting, 1,000 psi -28.3- in2 bore area FIGURE 14.— TRS cylinder cross section. pressure transducer was located between the TRS cylinder's load-check valve and the flow-control valve to measure the hydraulic pressure supplied to the TRS cylinders. Bridge amplifiers were used to condition the load cells and pressure transducer signals. Data were recorded on a tape recorder. The data display was generated by a strip chart via tape play- back. Pretest physical calibrations were conducted for all transducers. Two load measurement tests were con- ducted. For both tests the HFB was started, and the TRS was hydraulically powered against the steel plate until the relief-valve pressure setting was reached. The TRS flow-control valve was then closed. The HFB hydraulic pump was shut off 5 min after the TRS was set. The TRS remained in contact with the steel plate for 30 min and was then FIGURE 15.— TRS load measurement test configuration. 23 lowered. Load cell and pressure trans- ducer outputs were recorded continuously during these tests. Test results are shown in table 8. Tests were conducted at two different hydraulic pressure relief settings. For the first test, the pressure at the relief-valve setting was 998 psi. The initial measured load at this pressure was 26,107 lb. The pressure measured by the transducer located between the TRS load-check valve and flow control dropped to psi after the flow-control valve was closed. The load measured 26 min later was 23,871 lb. For the second test, the pressure at the relief-valve setting was 527 psi. The initial measured load at this pressure was 12,682 lb. The load measured 22-min later was 10,304 lb. The data indicate that the TRS can hold loads without major leak -off. TABLE 8. - TRS load-test summary Test Pres- sure, Load cell, lb Total number 1 2 3 force, psi lb 1 998 11,445 8,212 6,450 26,107 il X • • • ♦ 10,396 7,309 6,166 23,871 2 527 5,050 4,265 3,367 12,682 2 4,071 3,433 2,800 10,304 26.67 min later. The load exerted by the TRS against the mine roof cannot be considered the capac- ity of the TRS. Should the roof exert a load greater than the set load, the pressure inside the TRS cylinder will increase until the cylinder fails. The cylinder has a pressure rating of 5,000 psi that corresponds to a hydraulic capacity of 125,000 lb. NOISE SURVEY The objective of the noise survey was to evaluate the noise level at the HFB operator stations in various modes of operation. The noise survey was con- ducted for stationary and mobile opera- tion of the HFB. The stationary noise survey consisted of 14 measurement loca- tions, 4 geometries, and 2 operating modes. Figure 16 is a plan view of the HFB that defines the stationary measure- ment locations. The measurement geome- tries were bolter fully retracted and full left; bolter fully retracted and full right; bolter fully extended and full left; bolter fully extended and full right. The two operating modes were only pump operational; pump, conveyor, and breaker operational. A calibrated sound-level meter was used to measure sound levels. The microphone frequency response was set to frontal for all measurements. Octave band A weighted measurements were taken via the fil- ter set attached to the meter. The ini- tial set of measurements consisted of background levels with the unit nonope rational. A total of eight static tests were gen- erated for the staionary tests. Posi- tions 11, 12, 13, and 14 were at the operator stations of the bolter module and moved relative to the main body of the machine as the bolter boom was posi- tioned. Positions 5 and 7 also moved relative to boom position. For the stationary tests, background noise had no effect on the measured data, since the background noise levels were 15 to 20 dB below measured noise lev- els. Positions 8 and 9 exceeded 90 dBA for operation of the machine in the pump- only mode. These measurements were 1 m from the side of the machine at a 1.2-m elevation. The 1-m distance was chosen because this would be the typical dis- tance at which an observer would be standing. The pump motor appeared to be the primary source of noise with the 1-kHz octave band dominating. All other measurement locations were below 90 dBA for pump-only operation of the machine. 24 LEGEND • I Measurement position Positions I - 10- At 4 -ft elevation Positions 5~ 7- Move with bolter boom Positions l|-|4 : At 5-ft elevation A-WEIGHTED SOUND PRESSURE LEVELS, dB (RE 20 flPd) Measure- ment position Octave band center frequency, Hz Overall, 31.5 63.0 125.0 250.0 5000 IK 2K 4K 8K 16 K 20-20,000 Hz 1 20.7 35.3 53.6 68.0 67.4 69.4 71.6 64.2 470 30.0 75.7 2 23.0 38.7 52.9 66.6 64.0 69.9 71.6 64.4 46.8 30.5 74.6 3 24.3 40.8 56.2 65.9 68.5 71.3 73.4 68.2 48.5 30.4 76.5 4 25.0 41.0 56.5 71.0 72.6 76.7 72.5 70.1 52.0 34.2 80.4 5 23.5 40.4 55.8 69.7 71.3 725 72.2 68.2 51.4 37.4 77.5 6 23.2 38.1 53.1 59.0 69.0 72.7 71.3 67.8 49.0 30.4 76.0 7 22.5 39.0 53.5 68.1 7Z5 78.0 76.7 72.3 54.1 38.4 81.8 8 45.0 45.3 597 726 81.1 88.5 88.0 842 66.8 50.2 92.9 9 46.7 45.5 605 778 83.2 90.3 87.8 83.2 67.2 51.6 93.6 10 25.4 41.8 56.6 73.6 77.1 83.2 81.1 78.6 60.5 42.4 86.6 II 23.4 41.3 54.7 70.3 703 74.1 72.9 69.7 52.3 34.7 78.8 12 20.7 39.6 54.1 68.8 70.2 73.7 73.1 68.2 52.2 32.9 78.2 FIGURE 16.— Typical sound-level data sheet. 25 Activation of the conveyor and breaker, in addition to the pump, resulted in positions 1, 4, 8, 9, and 10 being equal to or exceeding 90 dBA. The 1- and 2-kHz octave bandwidths dominated for these measurement locations. The bolter-opera- tor measurements locations did not exceed 90 dBA. Pass-by noise measurements were con- ducted for the right and left sides of the HFB. These measurements were taken at a 1-m distance from the outermost edge of the machine. The sound-level meter had peak hold capability, which measured the overall weighted noise level recorded as the machine trammed past the observer. Elevation of the measurement was 1.2 m. Following the pass-by tests, the ac output of the sound-level meter was input to the HP spectrum analyzer. The ana- lyzer accumulated spectral data in the peak hold mode, which allowed qualifi- cation of the noise into the frequency domain as the machine trammed past the sound-level meter. The analyzer then generated a spectral plot of the X-Y recorder. Pass-by tests were conducted with the conveyor and breaker inoperative. The right side of the machine had a 97.5-dBA peak reading at 1 m for the pass-by; the left side had 89.7 dBA. Figure 17 shows the peak hold spectrum generated by the machine during the pass-by. The spectrum for the right side (17.4) shows that most of the noise is between 800 to 2,000 Hz, and correlates with the pump motor. The left-side (175) spectrum shows no domi- nating noise source, since the spectrum has no dominating peaks. The pump motor is a major noise source on the HFB. Several measurement loca- tions exceeded 90 dBA primarily from pump-motor noise. Most of the pump noise lies in the 1- and 1-kHz octave bands. Since MSHA uses exposure criteria to establish noise limits, ^ it is unlikely that an operator would be stationed con- tinuously (8 h) in areas around a machine that showed sound levels over 90 dBA, especially if the operator uses the radio remote control. 100 < CD •a LU > LU UJ CC 13 CO CO LU ce 0_ o to 12 3 4 5 FREQUENCY, kHz FIGURE 17.— Right- and left-side passby noise spectrum. LIGHT SURVEY The objective of this test was to con- duct a light survey of the HFB to eval- uate incident light levels around the machine when used in an 18- by 6-ft entry. MSHA^ requires that the luminous intensity (surface brightness) of sur- faces in a miner's normal field of vision and of work areas required to be lighted be no less than 0.60 fL. All measurements were made at night with the HFB located 80 ft south of the north wall inside the test building. A Panlux electronic light meter was used to measure incident light at designated locations on an imaginary box over the machine. Two survey rods were used to locate measurement locations. The imagi- nary box was scaled to simulate an 18- by 6-ft entry. MSHA has different requirements for illumination on different types of equip- ment. Since the HFB is a hybrid machine and has no distinct classification, mea- surements were taken as if the machine 5 CFR Title 30.70.502. 5 CFR Title 30.75.1719-1. 26 were a hopper feeder, and then as a bolter separately. When the chassis was considered as a hopper feeder, measure- ments were taken in a plane 10 ft forward of the front of the chassis and 5 ft to the rear. When the bolter module was considered a bolter, measurements were taken in planes 6 ft from the bolter- operator's station. Figure 18 shows mea- surement locations when the machine func- tioned as a hopper feeder. Figure 19 shows the measurement locations when the machine was considered a bolter. The light meter was held parallel to imagi- nary planes for all measurements. Footcandle Light loss measurement factor (0.77) Reflectance of x underground >0.06 fL surface (0.04) Locotion Light, fc Tl 1.0 T2 2.0 T3 3.2 T4 5.7 T5 1.3 T6 1.7 T7 5.0 T8 1.4 T9 15.0 T 10 2.8 T II 1.5 T 12 6.5 T 13 1.6 T 14 2.3 T 15 2.7 TI6 .8 TI7 2.6 T 18 ai 7 19 4.4 T20 .7 •TI6 •TI7 'TI8 •TI9 T20« TI5« FIGURE 1 8.— Top incident light measurements for the hopper feeder. T1 measurement location (6-ft elevation). BTIO BTIl BTI2 • • • — BT7 BT8 BT9 BT4 4'T ' BT5 BT6 BTI BT2 BT3 12' FIGURE 19.— Top incident light measurements for the bolter. BT1 measurement location (6-ft elevation). Location Light, fc BTI 0.3 BT2 .8 BT3 .45 BT4 1. 5 BT5 .9 BT6 1. 6 BT7 I.6 BT8 1. 2 BT9 2.5 BTIO .95 BTIl .8 BTI2 1. 8 From this equation, the minimum allow- able incident light for the floor, ribs, and ceiling of a given entry size is equal to 2.0 fc. Figure 18 tabulates the incident light measurements when the machine is consid- ered a hopper feeder. Several of the readings are below 2 fc, but since no ceiling or physical walls were available for reflection, it is assumed that the lighting would be adequate underground. Figures 20 and 21 tabulate the incident light measurements when the machine is assumed to be a bolter. The bolter has insufficient light to meet MSHA require- ments; however, since the bolter will be operating next to a continuous miner with proper lighting, it is assumed that the work area would be lighted sufficiently. SHUTTLE-CAR LOADING TRIAL In some mining situations, it is possi- ble for the HFB (with the bolter module removed) to be directly loaded by a shut- tle car. To evaluate this configuration, the HFB was loaded by a National Mine Service Model MC36-24S shuttle car with an extra-wide chain conveyor and boom. B5 B6 B7 B8 Bl £X^ B2 B3 12'- Location Light, fc Right Left Bl B2 B3 B4 B5 B6 B7 B8 0.7 .6 1.0 1.4 .8 1.2 .8 1.7 0.3 .25 .25 .4 .45 .2 .3 .3 B4 H FIGURE 20.— Incident light measurements for the bolter sides. B1 measurement location (6-ft elevation). M'H Location Light, fc Front Rear Bl B2 B3 B4 B5 B6 2.0 3.7 1. 7 2.0 2.7 1. 6 0.I5 .1 .15 .1 .1 .1 FIGURE 21 .—Incident light measurements for the bolter front and rear. B1 measurement location (6-ft elevation). 27 The shuttle car has an overall width of 11 ft and a discharge conveyor width of 5 ft, 6 in. The shuttle car was loaded with a mixture of coal and dirt; the shuttle-car boom was raised and centered over the HFB hopper. Figure 22 shows the relationship of the shuttle-car boom to the HFB during the loading trial. The HFB breaker and conveyor were started, and the shuttle-car operator activated the shuttle-car conveyor intermittently to minimize spillage at the front of the HFB hopper. During the trial, there was spillage over the sides and front of the HFB hopper (fig. 23). To make the units more compatible, it is recommended that the inby end of the HFB be modified to better interface with the discharge end of a shuttle car. SURFACE TEST SUMMARY Surface testing and evaluation indi- cates the HFB is worthy of an in-mine trial. Specific achievements derived from the surface test program are as follows : The HFB can be easily trammed using the radio remote control unit. The average tram rate when maneuvering through cross- cuts with the extended bolter module was 77 ft/min. The HFB bolter units and the three- stage dust-collection system perform effectively. During a bolter evaluation, each unit drilled through 5,000 psi compressive-strength concrete mix without a problem. Time-study data were gathered when the HFB was operated in a simulated produc- tion mode with a two-pass continuous miner while advancing 24 ft with roof bolting and position changing. A plan for "in-place" entry position changing of the HFB and a continuous miner was established. Several time studies were conducted with this plan, and the average time required for an in-place position change was 3 min, 9s. The HFB was successful in breaking rocks up to 18 by 30 by 24-in. The HFB successfully held an 8,000-lb weight that was suspended from the tail boom. During a coal-conveying trial, the HFB loaded 680 st of coal during 560 min of operating time. There were 10 minor failures that could be partially attrib- uted to conveying wetted coal. The HFB discharge rate was always below 6 st/min. Airflow and performance measurements taken on the modified dust-collection system were consistent with MSHA recom- mendations. The primary dust-collector boxes have an approximate capacity to hold the dust produced from 35 lineal ft of 1-3/8-in-diam holes. The maximum drawbar pull of the HFB chassis was 38,000 lb on a dry, com- pacted, clay-fly ash floor; the maximum drawbar pull on wetted ground was 32,000 lb. The TRS load tests determined that with relief pressures of 998 and 527 psi, the TRS-generated roof loads were 26,107 and 12,682 lb, respectively. The TRS main- tained these loads effectively without major leak-off. Noise survey tests indicate that the major noise source on the HFB is the electric motor driving the main hydrau- lic pump. Noise levels measured at vari- ous operator positions while the machine was operated in different modes indi- cate that the HFB will comply with MSHA regulations. Light survey tests show that the HFB has adequate lighting to meet MSHA requirements if the chassis is consid- ered a hopper feeder. Lighting is inade- quate if the machine is considered a bolter; however, illumination may be ade- quate when the bolter module is located beside a continuous miner. The HFB is a hybrid machine with no distinct MSHA classification. The HFB can be operated as a hopper feeder, with the bolter module removed, inby of a continuous face haulage system. 28 FIGURE 22.— HFB shuttle-car loading trial. FIGURE 23.— Spillage during loading trial. REPAIRS AND MODIFICATIONS 29 Numerous repairs and modifications were made to the HFB to correct deficien- cies observed during surface testing: MINING PLANS Appendix B is a listing of major modifi- cations; the repairs are presented in appendix C. The HFB machine concept is adaptable to a variety of mining plans. It can bolt beside a two-pass continuous miner, load into either a continuous haulage system, or intermittent (shuttle-car) haulage system. There are substantial benefits using the HFB to bolt beside a two-pass contin- uous miner: Tram time between cuts is minimized because entry-to-entry place changes between the continuous miner and roof bolter are replaced with side-to- side equipment changes between the con- tinuous miner and HFB bolter module. Supervision of the face crew is improved, since the foreman can simultaneously observe both mining and bolting. There are several benefits to using the HFB as a surge car-breaker inby of a continuous haulage system: The HFB can level the instantaneous surges produced by the continuous miner, thereby allowing use of smaller sized continuous haulage systems; the HFB can support the inby end of the continuous haulage system, thereby allowing a faster miner place change and cleanup rate; and the breaker on the HFB eliminates jamming in the face haulage system and the need for a feeder-breaker on the section belt. HFB WITH TWO-PASS CONTINUOUS MINER The HFB can be used to bolt beside a two-pass continuous miner. Figure 24 shows the configurations of the HFB and miner through 10-ft-deep right- (RH) and left-hand (LH) cuts. At the start of the RH cut, the HFB bolter was 10 ft from the face and 10 ft from the miner cutterhead. During a 10-ft-deep RH box cut, the bolter module places six roof bolts on the left side of the entry. At the completion of a RH cut, ventila- tion is advanced into the box cut, and the bolter module and continuous miner exchange places within the entry. During a 10-ft-deep LH open cut, the bolter module places six roof bolts on the right side of the entry. At the completion of a box and open-cut sequence, roof bolts are installed to within 10 ft of the face. An additional roof bolter should be kept on the section to bolt cross- cuts. Because of the difficulties in providing sufficient clean air for the bolter operators, 20-ft-deep cuts are not recommended. Start RH cut Complete RH cut Place change and advance ventilation 'fi W 11 ' Start LH cut Complete LH cut Place change and advance ventilation KEY — - Airflow ~-~» Brattice '. Roof bolts FIGURE 24.— Face-equipment configuration for 10-ft cuts. 30 Mining rates for the HFB continuous miner system can be estimated by tabu- lating time-study data obtained during surface testing. Table 9 presents HFB rates for 8- and 12-ft bolter advances. Bolter-module activities were divided into three elements: drill and bolt, advance bolter module, and place change. The advance-bolter-module time (1 min, 43 s) and the place-change time (3 min, 9 s) may not vary much for different mining conditions. However, drill-and-bolt time will vary depending on the roof-bolt type and drilling conditions. The drill-and- bolt time during surface testing was 3 min, 12 s for 42-in-long, 1-3/8-diam mechanical roof bolts. However, under the same conditions, the drill-and-bolt time for an experienced underground crew can be as low as 2 min, 30 s assuming two bolts are installed simultaneously. 7 Suboleski, S. C. (A. T. Massey Coal Co., Inc.). Private communication, 1986; available upon request from R. J. Evans, BuMines, Pittsburgh, PA, 2 pp. TABLE 9. - HFB mining rates 1 Number of Time, events min:s 8 -ft BOLTER-MODULE ADVANCE 4 12:48 Advance bolter module . 2 3:26 2 6: 18 Total 22: 32 2:49 12-ft BOLTER-MODULE ADVANCE 6 19:12 Advance bolter module . 4 6:52 2 6: 18 Total 32:22 2:42 Rates assume that 4 roof bol ts are installed across width of entry. Average event time is 3: 12, from table 3. Average event time is 1: «, from table 3. Average event time is 3: 09, from Therefore, a 12-ft advance could be com- pleted by an experienced crew in 9 min, not counting a "place change." Assuming the place change takes roughly 3 min, the 12-ft advance for an experienced crew will take a total time of 12 min. Depending on the drilling condition, crew experience, and roof-bolt type, a table can be developed, as shown in table 9, to aid in estimating productivity. For example, in table 9 a 12-ft face advance, as determined from surface test- ing, takes 32 min, 22 s. Assuming a 20- ft-wide entry, 6-ft-high roof, 4- by 4-in bolting pattern, approximately 2 ft/min drilling rate, 360-min production time- shift, 80-lb/ft 3 coal density and a 12- ft-deep cut, the following formula could be used to estimate run of mine (ROM) coal production using the HFB: 360 min x 1 cut x 20- by 12- by 6-ft 1 shift 32.4 min 80-lb coal X = X ft 3 640 st — ■ ■ ■ ■ • shift 1 cut 1 st 2,000 lb (1) place-change time study. When using 12 min for a 12-ft deep cut, which represents the best time for an experienced crew, the estimated produc- tion derived using the above formula is 1,728 st per shift. Other mining rates could be estimated by changing the equation variables. For example, changing the roof height to 4.5 ft and keeping the other variables con- stant, ROM production can be estimated at 480 st per shift. In using this formula, caution should be observed. This formula does not include the extra time required for place changing between entries and other mine-specific delays. The depths of cut for the continuous miner and bolter-module advance are related. Assuming that roof bolts are installed on 4-ft centers and the depth of cut is 10 ft, bolter-module advance will alternate between 8 and 12 ft. 31 Figure 25 shows a proposed mining plan for two-pass break-to-break mining with the HFB using 10-ft cuts. Tram time between entries is required only when an entry is driven the length of one breakthrough. Not all cuts can be easily bolted by the bolter module: The start of turnouts would be difficult to bolt because of limited room. It would also be ineffi- cient for the HFB to bolt the 10 ft of roof at the completion of an entry, because the HFB should be moved with the miner to allow mining in another entry. Areas that are difficult to bolt with the HFB will be bolted by a separate bolter maintained on the section. A minimum of four personnel is required for the HFB continuous miner face crew: a miner operator, an inside bolter opera- tor, an outside bolter operator, and an HFB chassis operator. Figure 26 shows the positions of all four operators during a LH miner cut. Figure 27 shows the positions during a RH miner cut. Appendix A more fully explains the positions and responsibilities of each machine operator during a box- and open- cut mining sequence. When the HFB is used to bolt beside a miner, the following mining plan is recommended: The maximum entry width with a 4-ft bolting pattern is 20 ft. The minimum entry width should be 18 ft. A 20-ft entry width should be maintained, if pos- sible, to maximize the bolter-operator's working area. The cut plan should be designed to keep the bolter operators in fresh air. The 10-ft cut plan, shown in figure 26, is recommended. A staggered 20-ft cut plan is not recommended, since the bolter operators must work directly in return air. LEGEND 2 Entry sequence CS Cut sequence Section belt Not to scale FIGURE 25.— Mining plan for 20-ft cuts. MSHA requires that face areas be rock- dusted to within 40 ft of the working faces. 8 Provisions should be made to incorporate rock dusting in the break-to- break cut and in-place change sequence. Panic-bar or other type emergency stop switches should be installed along both sides of the continuous miner from the cutterhead pivot point to the rear of the chassis for additional bolter-operator protection. A single-boom roof bolter should be available on the same section as the HFB. Turnouts will be difficult to bolt with the HFB. Also, the HFB should not be used to bolt extremely bad roof beside an operating miner. Because of the previously discussed bolter-operator hazards, the bolter oper- ators should be thoroughly trained to properly operate the bolter prior to pro- duction use. 8 CFR Title 30 Part 75.402. 32 FIGURE 26.— Bolter module positioned for LH miner cut. FIGURE 27.— Bolter module positioned for RH miner cut. 33 An adequate supply of spare parts should be available at the mine site to minimize downtime. BOLTER-MODULE HAZARD ANALYSES Although productivity benefits are pos- sible by using the HFB to bolt beside a two-pass continuous miner, the operators may be exposed to more hazards than conventional roof-bolter operators. The hazards are primarily caused by the prox- imity of the HFB bolter operators to the operating continuous miner. Figure 28 shows operator locations for the HFB bolting beside a two-pass continuous miner in a 20-ft-wide entry. The inside bolter operator must work in a 3-ft-wide area between the continuous miner and the bolter module. The outside bolter opera- tor must work in a 4-ft^wide area between the bolter module and the coal rib. Both bolter operators are typically located 12 ft from the front of the continu- ous miner cutterhead. The following are potential bolter-operator hazards: /////A ^~ Right bolter- ^Z^zli operator's station Walkway -Left.bolter- > operator s station rMiner cable hung on mine roof Roof bolts installed on 4- ft centers FIGURE 28.— HFB operators' areas. 1. Sideways continuous miner movement Although the inside bolter operator is within good view of the continuous miner operator, sideways movement of the con- tinuous miner during cutting could pinch the inside bolter operator between the miner and the bolter module. Miner move- ment could be caused by unintentional activation of the miner crawler controls causing the miner to pivot or by cutting hard material. Continuous miner cable handlers who are sometimes positioned between the continuous miner and the coal rib can avoid these hazards because they constantly watch the miner and its cable. The inside bolter operator must con- centrate on roof-bolting operations and therefore may not be aware of continuous miner movement. To minimize this hazard, panic-bar or other types of emergency stop switches could be installed along both sides of the continuous miner to de-energize the miner, should it come too close to the bolter operator. 2. Unintentional bolter-module movement Unintentional activation or "sticking" of the solenoid-controlled bolter-module tram motor or rotary actuator could pinch the bolter operator between the bolter module and the miner or coal rib. This can be controlled by effective train- ing to assure proper positioning of the bolter operators during bolter-module tramming. The bolter-tram and rotary- actuator rates can also be reduced to slower safe speeds. 3. High noise levels The bolter operators must work in a high-noise area; therefore, hearing pro- tection may be required to comply with MSHA standards. The high noise level limits the ability of the bolter opera- tors to hear noise generated by unstable roof and the ability of the face person- nel to communicate. 34 4. Projectiles Although it is unlikely, the bolter operators typically located 12 ft from the front of the continuous miner cutter- head could be struck by projectiles gen- erated by cutting operations. 5. Ventilation The bolter operators will be subject to some of the dust generated by the contin- uous miner at the coal face. It is rec- ommended that dust respirators be worn by the bolter operators. 6. Mine cable handling As shown in figure 29, bolting on the right side of the miner requires that the continuous miner trailing cable be sus- pended over the bolter module. The con- tinuous miner cable must be hung from the roof during every LH cut, which creates a potential for back injuries and electri- cal hazards. In the current bolter-module design, roof bolts are installed manually by two bolter operators. A future concept design can be envisioned that would fea- ture remotely controlled or completely automated roof control without the need for bolter operators to work near the face area. The design and evaluation of this future concept is not included within this scope of work. HFB WITH CONTINUOUS HAULAGE The HFB can be used with or without the bolter module as a surge-car-breaker inby of a continuous face haulage system. With the bolter module removed (fig. 29), the hopper feeder can be used in a con- ventional place-changing mine plan. The hopper feeder is compatible with a vari- ety of continuous face haulage systems. FIGURE 29.— Hopper feeder. 35 Miner operator Hopper -feeder operator FIGURE 30.— Hopper feeder used with MBC. '////////////////// //////////////////////// ////////////////////////////////////A Hopper-feeder tail boom- opper of inby MBC unit //////nii))/i/i////>//i///////////////n////////'i//jH////////////i/ii>i/i/ii 3' takeup FIGURE 31.— Hopper feeder MBC interface. It can support the inby end of a haulage system, or it can operate independently of the haulage system. Figure 30 shows the hopper between a continuous miner and the Bureau's monorail bridge conveyor (MBC). Four face personnel would be required: a miner operator, a hopper- feeder operator, a cable handler, and a (MBC) continuous haulage operator. The tail boom of the hopper-feeder (fig. 31) can be used to support the inby end of a continuous haulage system. Takeup capa- bility between the two units would be required, since the two systems will most likely have different tramming rates. Figure 32 shows a mine plan for the hopper-feeder used with continuous haulage. Not to scale Section belt FIGURE 32.— HFB with continuous haulage. Numbers indicate cut sequence. CONCLUSIONS The HFB is a prototype multifunctional machine that was designed to increase productivity and improve safety by elimi- nating place changing between the contin- uous miner and the roof bolter. Exten- sive surface testing was conducted at the Bureau's METF to evaluate criteria and to identify and make necessary modifica- tions before making an underground trial. Numerous modifications were made to improve system performance and reliabil- ity during surface testing. Successful test results under simulated mine condi- tions indicate this innovative system has the potential to increase productivity by combining functions typically performed by a roof bolter, surge car, and feeder breaker. Mining plans were developed for a two-pass continuous miner and a contin- uous haulage system. An in-mine trial is scheduled to be conducted at an under- ground coal mine using the hopper-feeder (without the bolter) in conjunction with a continuous face haulage system. 36 APPENDIX A.—HFB DEPLOYMENT Figure A-l shows the operating sequences of the HFB beside a two-pass continuous miner (CM). tubing or '/ brattice-ft 4 Nv\\\v. cm; HFB B If. CM HFB Vh KEY 1^ Unbolted roof • Inside bolter operator ■ Miner operator A Outside bolter operator ♦ HFB chassis operator HFB HFB HFB H FIGURE A.1— HFB deployment. 37 APPENDIX B.—HFB MODIFICATION SUMMARY Date Modification 4/83 A variable flow-control valve was installed in parallel with the bolter module tram motor. 4/83 The left inby light bracket was moved 6 in farther outby on the chassis. 5/83 A frame was installed to capture the bolter vacuum hoses. 10/83 The inby edges of the hopper were trimmed back and stiffened. 10/83 Belt "skirting" was installed under the inby edge of the hopper. 11/83 Belt "skirting" was installed under the upper edge of the sideboards on the left side of the HFB. 12/83 The bolter-module's hold-down bar was removed and cover plates were installed. 1/84 The solenoid-controlled hydraulic valves for the bolter-module tram and bolter- module rotary actuator pilot circuits were relocated between the TRS cylin- ders (into the space previously occu- pied by the primary dust-collection boxes) . 6/84 The bolt tray on the bolter module was enlarged from 20 by 56 in to 36 by 56 in. An additional rack for storing bolts was added to the bolt tray. 6/84 The primary dust-collection boxes were relocated to underhung positions beneath the bolt tray. 6/84 The hydraulic hoses, vacuum hose, and control cable to the bolter module were rerouted for a takeup extension arrangement. Reason The valve was required to vary the bolter module tram rate. The light bracket interfered with boom traverse. The hoses would catch on bolter hardware during mast movement. This change would allow greater access to the hopper by a miner discharge boom. The skirting would keep material from accumulating on the exposed hydraulic components. The belting provided an effective guard for the breaker roller chain. Initial tests showed that the hold-down bar was not required. This relocation improved access to the numerous hydraulic valves on the bolter module. The increased area on the bolt tray was desirable for storage of extra supplies. The original positions of the pri- mary dust-collection boxes were between the TRS cylinders. This was undesirable since the door to the boxes was inby the TRS. The original festooned extension arrangement would not work with the relocated dust boxes. 38 Date Modification Reason 1/85 A pressure-relief valve was installed in the TRS circuit. The valve was specified in the hydraulic schematic but never installed on the HFB. 2/85 The two diagonally oriented fluorescent luminaires on the inby end of the bolter module were replaced with one horizontally oriented luminaire. 2/85 The two sodium-vapor luminaries on the tail boom were changed from a vertical to a horizontal orientation. The existing power supply was insufficient to power two luminaires. The luminaire entry glands were prone to damage in the vertical orientation. 6/85 The adjustable mercury tube overloads between the output side of the SCR controllers and the dc tram motors were adjusted to trip at 300 A dc. The initial setting for the right overload was 290 A dc. The ini- tial setting for the left over- load was greater than 350 A dc. The right overload caused fre- quent tripping of the main breaker. 6/85 The valve of the shunt resistors con- nected across the line current trans- formers was decreased from an equiva- lent value of 83 D to 80 D. The change decreased the value of the feedback voltage supplied to the current trip and current limit logic circuits. This was required to eliminate frequent logic tripping in the tram con- trol circuit. 8/85 The value of the capacitor (4 on ESD drawing No. 5152954) was changed from 250° to 470° F. This change decreased the accel- eration rate of the acceleration ramp generator in the tram- control circuit, thereby decreas- ing current overshoot and resul- tant tripping. 39 APPENDIX C.—HFB REPAIR SUMMARY Date Modification 4/83 The weld between the TRS hydraulic cylinder and the base of the TRS was rewelded. Reason The original weld cracked, causing hydraulic oil to leak from the TRS. 5/83 The left bolter torque relief valve was replaced and relocated. 6/83 A reversing SCR and three integrated circuit chips in tram logic cards were replaced. The pump motor power leads were retaped. The original relief valve was struck by the rotary actuator assembly. A ground short of one phase of the three-phase pump motor caused the voltage potential of the other two phases to increase. This increased potential caused the failure of the solid-state devices. 10/83 The pipe nipple connecting the pump motor to the pump motor's junction box was replaced. The pump-motor's junction box broke from the pump motor. Only one set of threads on the pipe nipple was engaged into the pump motor. 11/83 The return spring on the solenoid- controlled bolter tram-pilot circuit was replaced. 5/84 A broken lead on the pulse transformer board of the left crawler-reversing SCR was repaired. 12/84 The left bolter thrust cylinder was sent to Fletcher Co. and repaired. The valve would occasionally stick in the open position, requiring emergency shutdown of the HFB. The HFB would not tram. A pinhole leak was found in the intermediate cylinder. Oil would shoot out during cylinder retraction. 5/85 Two 5/8-in-diam bolts that hold the bolter module boom onto the boom traverse bracket were replaced. The bolts failed during tramming in rough bottom conditions and caused the bolter module to tip over. 11/85 The conveyor's flexible sideboards were replaced. The original sideboards were dam- aged by the addition of welded extensions. U.S. GOVERNMENT PRINTING OFFICE: 1988 — 505-016/80,010 INT.-BU.OF MINES,PGH.,PA. 28634 U.S. Department of the Interior Bureau of Mines— Prod, and Dtstr. Cochrane Mill Road P.O. Box 18070 Pittsburgh, Pa. 15236 AN EQUAL OPPORTUNITY EMPLOYER OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, WOO "2 Do not wish to receive this material, please remove from your mailing list* "2 Address change. Please correct as indicated* 6**563 88 \— 4. V o V . *^ 0* o i» O 4V * """ -V * W> /«-% /d--X A''^'" % • A V «t*. - V-tf 5 <* *<..«* .0 S°* . P* .*l^ •> cx <'/> > • ^ >v ^O^ ^ %. "•' * aV -K ■ ^ ^ AT "^ a v ^ : ai^° ^^ £mM$» aV^ ^^r £r ^ JP^ A ^ A* • fife ' ^ > &'"^ WMW A A ' ^ J .®iiS* .«? ^; ^ A^ •fife* ' 9 \^ iP^K 4 CU 4> x» **te A^ * *^ A* .9* »''°'. *» V .« %/ .• V *5- *o . k * A :. >o a •i? »'fta'. "^ i,. V **-»^*- ^ A^ O- * * .»1^% ^°o v ..i^Lv «i ~l~ - < • < J^ ^°«* 'o^^^.o 5?"^ * ^ V ^ •••'• A " e ^ A*' **«* ^ £°* *o. <£■> * * A'"\> ■• l o*'' "*^. 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