tof Engine 1 Governors ZU BE ISHING<« Stick Rounad'-Head Wood! Screw FIG. 18. MEASURING SLIDE FOR USE WITH PISTON VALVES Fig. 18 for locating the steam ports in the valve chest. These steam port locations will, as is hereinafter described, be transferred to the steam port templet. The sheet steel head, S, may be of approximately the proportions as spe- cified but, in any case, the dimension L should be at least zg in. less than the width of the engine steam ports. Twe pieces of smooth clear pine, each about 1% in. thick and about 1 in. wide will be required. Both should, at the start, be about the same length as the measuring rod. All faces and ends should be square and true. Remove the valve chest cover and the valve stem stuf- fing box gland. Disconnect and remove the valve from the valve chest. Insert the measuring rod into the valve chest so that one of its index edges is against the further edge of the farthest steam port. With a knife blade, cut a cor- responding line, A on the face of the rod exactly at the 30 level of the valve chest face. Similarly, locate on the measuring rod lines B, C and D, which respectively cor- respond to the other edges of the steam ports. MAKING A PISTON VALVE TEMPLET Now, lay one of the sticks, which was prepared as above, on the measuring rod. With a try square and knife blade transfer the lines from measuring rod to the 1% in. face of the stick. In the illustrations, the width of the sticks is shown exaggerated for clearness. - Draw pencil “hatch” lines on those portions of the stick’s face which do not Steam-Port ,Port Locations. Termpletr Center Line} Piston Valve ,---Valve Face . . ‘ ’ ’ ¢ ’ s Par, A. Round-Heaa Center Lines ¢ AP aster Fr“ On Templets-*,-” 4£-otrap-/ror fs Y Support G *--Crank-End ISS a Port e)<--- Va/ ve a chest Stud ¥\,2 FIG. 20. VALVE TEMPLETS METHOD APPLIED TO A VERTICAL ENGINE lie below the top face of the valve chest when the valve is vertically central in the valve chest in relation to the ports. Now lay off on the valve templet below J a distance JK, which is equal to IJ. Cut the templet off square at K and it will be complete and of correct length. It is necessary, as indicated in Fig 20, to arrange the valve templet on the engine valve chest. This particular arrangement is for a vertical engine but a similar scheme may be used for horizontal engine. The main point to keep in mind is that the port templet must be fixed in some way so that it will not accidentally be moved. The method shown in Fig. 20 is carried out as follows: Bend a piece of strap iron to form a support, G, for the 32 steam-port templet. Drill the short leg of the support to accommodate one of the valve-chest studs and drill the long leg to take three round-head wood screws. Replace and reconnect the valve in the chest. Secure the steam- port templet to the valve chest, with the “H” end of the steam-port templet exactly on a horizontal line with the top face of the steam chest. Now place the valve templet alongside of the steam-port templet with the lower end, K, of the valve templet resting on the upper face of the valve. The end K should always, when the templets are in use, rest on the upper end of the valve. Now, if the templets have been accurately made, they will visibly reproduce, out- side of the steam chest, the invisible events which are occurring within it. To use the templets for valve setting, it is merely nec- essary to measure the valve events which occur from the templets—instead of measuring them directly from the actual valve and ports. In other words the procedure is exactly the same as for a D valve. After the valve has once been set correctly, it may be desirable to label and retain the templets for future use. But, if the proper trammel is made and center-punch reference marks are spotted on the valve stem, the use of the templet for reset- ting will be unnecessary. SETTING SHAFT-GOVERNED VALVES Most engines are rated about 14 cut-off, hence when setting a valve which is driven by a shifting eccentric, the governor should be blocked out to a position that will give that cut off. The operation is then the same as that for the D valve with fixed eccentric, allowing, of course, for the reversal of motion if a reversing rocker is used between eccentric and valve. After the valve is set, the engine should be turned over and the crosshead position noted for cut off at each end. Sometimes it is desirable to adjust for somewhat greater lead for the crank end in order to bring the cut off more nearly equal but the head-end lead should never be cut down so as to show late on the diagram and the lead should never be so large as to cause racing at light loads. If the governor is so made or located that it can not be blocked out, the setting may be made with the governor 33 at the innermost position as the division of lead between the ends is not greatly altered by the change in position of the governor and the exact division of lead for best action can be determined by the indicator diagrams. If the governor turns the engine around the shaft to alter the lead as in some of the old time motions, the valve is set the same as the D valve with governor in innermost position. Sertina RIDING CUT-OFF VALVES To set the main valve of an engine with a riding cut- off valve proceed as with the common D valve by equalizing aa Eye SSE ET esse — ff i A TH eM Hi oem aw tile weet eee eee Bata JH | sa = Yor LL | wien, 7 peeri Pomsiee aoe) YY Y a ; =i5 LL G \ —~ Sy H ) WSs a SJ | 2 Gi 7 Gia , Ta} FIG. 21. SETTING MARKS FOR MEYER RIDING CUT-OFF VALVE the lead at the ends so that the valve has about 1/64 in. lead at each end. The main eccentric is then made fast to the shaft, and the setting of the cut-off proceeded with. Different portions of the stroke are laid out along the crosshead slide and from each end of the stroke. With the crosshead in the position at which it is desired that cut-off should take place, the cut-off valve is adjusted so that it just closes the port in the main valve, the governor being blocked out to running position. The engine is then moved to the corresponding position in the return stroke when the cut-off valve should just close the port in the 34 main valve. If the cut-off valve does not close the port in the main valve, the length of the valve rod should be changed and the cut-off is simply shifted until equal cut- off is obtained at both ends. In steam driven compressors built by the Chicago Pneumatic Tool Co. the Meyer cut-off valve is used on duplex compressors of 12-in. stroke and above. In this valve as shown in Fig. 21, the cut-off is adjust- able, allowing the compressor to operate at the most eco- nomical cut-off for the conditions existing. This is effected by means of an adjusting hand wheel which serves to revolve the right and left-hand-threaded valve stem thus drawing the cut-off valves together or spreading them apart. A range of from one-quarter to three-quarters cut- off is available and adjustment can be made while the machine is operating. An index block and scale indicate the points of cut-off. The valve gear consists of double eccentrics, cast inte- gral so that the position of the cut-off eccentric is fixed, once the main valve eccentric is set. INSTRUCTIONS FOR SETTING Piston RIDING CUTOFF Instructions for setting this valve are as follows: Draw the cut-off valves as close together as possible by turning the hand wheel. Set the main valve in the manner described for the plain D slide valve; the main valve eccen- tric should lead the crank by about 112 deg. Set the crank on head end dead center and scribe a ver- tical line on the crosshead and crosshead guide. ‘Then set the crank on crank end center scribing a vertical line on the crosshead guide in extension of the line on the cross- head. Now divide the space between the two lines on the crosshead guide into four equal parts scribing a line to indicate each division. Set the crosshead at half stroke and adjust the cut-off valve until it is just cutting off the port in the main valve. Move crosshead to the correspond- ing position for the other stroke, and the other cut-off valve should just close the port of the main valve. If it does not just close the port, the valve should be moved along on the stem to the correct position. These valves should be set to cut off alike at some pre- determined point, for the valves may be set to cut off alike 35 at any given position but they will not cut off exactly alike for any other position. The cut-off piston valves shown in the illustration are set entirely by tramming, as for a plain piston valve. On the main steam valve rod and the cut-off valve rod will be found shop tram marks with figures, indicating the dis- tance between them, stamped on the rod. When the valve rods are set so that the marks on them are apart the dis- tance stamped on the main valve rod, the cut-off valves are centered in the main valve. Remove the main valve from the chest and determine accurately the distances A, B, C, D, and HE. Replace the valve and connect up the valve gear. Set the main valve eccentric approximately 74 deg. behind the crank. Then with crank on head end center adjust valve stem until the distance from the face of the chest to exhaust ring equals (C+D—A). Place crank on crank end center and, using same reference points as before, check for distance (C+D+E) — (A+B). In case the distances do not agree, take up half of the difference on the valve stem and the other half by moving the eccentric. Continue in this manner until the lead at both ends is equal. The index block will be correct as it is correctly adjusted before leaving the factory. The method of setting the valve by allowing steam to blow through the cylinder with cut-off at various points should be used, and where possible the cylinders should be indicated. CHAPTER IV CORLISS VALVE SETTING HEN the various parts of a Corliss valve gear are in proper adjustment, the reach rod and the eccentric rod should be of such length that the rocker arm and the wrist plate will be plumb when the eccentric is vertical. Manufacturers of Corliss engines usually place a mark A, such as shown in Fig. 22, on the hub of the wrist plate FIG. 22. MARKING USUALLY FOUND ON WRIST PLATE OF CORLISS VALVE GEAR and three marks D, B and C on the wrist plate stud. When A coincides with B the wrist plate is in its central posi- tion and in this position the rocker arm and the eccentric should be vertical. When A coincides with B the wrist plate is at one extreme of its travel and the eccentric is on its dead center and when A coincides with C the wrist plate is at the other extreme of its travel, and the eccentric is on its other dead center. If the marks A, B, C and D are not on the wrist plate and stud, they should be placed on with a chisel, A and B being marked when the eccentric is vertical and the rocker arm and wrist plate are plumb, and D and C being marked opposite A when the eccentric is on its dead center. 37 SETTING SINGLE Port CoRLISS VALVE In order to show the method to follow in setting valves of the Corliss type an example will be taken of a valve of single port type, Fig. 23, with single eccentric. First, turn the engine over and see that the wrist plate travels equal distances each side of the central position. If not, make it do so by adjusting the eccentric rod when the gear is in one of the extreme positions as indicated by the marks on the hub. After this is done, the work of setting the valves pro- ceeds. The releasing mechanism for a valve of this type is shown in Fig. 6, Chapter I. Raise the hook rod and place 1 ; LAP OF VALVES 5 STEAM /EXHAUST LAP LAP % LE l MLL Le LL My T= ge) q (LIED addenda bidiiiddatiuu.2tn220..Qtunacnrx.rdncccQnnncccrnn ey WWM, FIG. 23. SINGLE-PORTED CORLISS VALVES the wrist plate in central position. Then remove the valve covers at the back side of the cylinder and a chisel mark will be found on the end of each valve. This mark is in line with the cutting edge of the valve and another chisel mark on the end of the counter bore, is in line with the edge of the cylinder port. With the hook on the steam arm engaging with the block on the dash-pot arm, the valve should be placed as shown in the sectional view of the cylinder in Fig. 23, having the steam lap and exhaust lap corresponding to the amount given in the table of Fig. 23 for the size of cylinder. The rods connecting the wrist- plate with the valve arms have right hand threads on one end and left hand threads on the other so that the length of the connection can be made greater or less by turning the rod one way or the other. In this way the cutting edge of each valve can be placed in the proper relation to the corresponding port edge of the cylinder as given by the table. 38 When valves are set the engine crank should be placed on one of the dead centers, say the one nearest the cylinder. The piston is then at the end of the stroke towards the head end of the cylinder. Move the wrist plate until the hook rod drops into place on the driving pin. Then examine the steam valve on the head end of the cylinder. The mark on the valve should be 344 in. nearer the center of the cylinder than the line on the cylinder corresponding to the edge of the port, this 4g in. opening being called steam lead. If it is much more or less than + in., loosen ra = wl = @ o w 2 Hi My VE MM Yj WT ace ibgudisddbbissideda Wh FIG. 24. DOUBLE-PORTED CORLISS VALVE the set screws in the eccentric and move the eccentric on the shaft one way or the other until the valve is in the correct lead position. When the correct position of the eccentric is found, mark the eccentric and shaft to cor- respond in such a way that it can be detected later, should the eccentric slip from its correct position. Then fix the eccentric on the shaft and replace the back valve covers and the engine should be ready to operate. SETTING DOUBLE-PorRT CoRLISS VALVES For setting valves of Corliss engines with double eccen- trics and double-ported valves as shown in Fig. 24, the Bates Machine Co. gives the following instructions: On the hub of the wrist plate, or of the steam valve crank where no steam wrist plate is used, and on the wrist- 39 plate base, or steam bonnet, will be found the chisel marks referred to at the beginning of the chapter. If the back valve-covers of the cylinder be removed, chisel marks will be found on the ends of the valves, and on the ends of the valve chamber counter bores, as for the single ported engine. Steam valves are set by the same process as for the single-ported, single eccentric engine, but given a negative lap, about 3%; in. for a cylinder 18 in. diameter and steam lead about 34¢ in. EXHAUST VALVE SETTING To set the exhaust valves, proceed in the same manner by raising the hook rod and placing the wrist plate, (for double eccentric engines, use the exhaust wrist plate), in the central position. The valve edge and port edge of each exhaust valve should then be brought in line with each other by adjustment of the valve rod connecting the wrist plate and exhaust arm, giving the valves zero lap in the central position. This is the only adjustment for a single eccentric engine. | For a double eccentric engine, now turn the engine over until the cross head is about 4 in. from the end of the stroke, say towards the head end. The exhaust eccentric should then be moved on the shaft, until the exhaust valve at the head end of the cylinder has its cutting edge in line with the port edge of the cylinder. This will give the proper compression for a medium sized cylinder, 22 to 24 in. diameter. For a smaller cylinder it will be better to place the cross head about 314 in. from the end of the stroke and for a larger cylinder about 41% in. Tighten the set screws in the eccentric, also nuts which have been loosened in making adjustments; replace the back valve-covers and then the engine should be ready for operation. Steam valves on engines with double eccentrics are given negative lap in order to give a later cut-off- where the load demands it. Where negative lap is used, it is necessary that the governor knock-off cams should be placed so that the dash-pot closes the valve at every stroke, other- wise there would be live steam on both sides of the piston at one point in every stroke. 40 ADJUSTMENT OF VALVE GEAR During the course of the valve setting work, it is well to note the clearance around the catch block. It is impor- tant to adjust the length of the dash-pot rods properly, because, if they are made too short, the valves will not hook on and, if they are too long, the valve stem is liable to be bent or the steam brackets broken or both. Yoke Fin. Spindle top: Steam Hook Spring. Hele for loadirg with shyt ran Fendulum Arm Yokes. Gov Rod Brass Heads. RS) Ys Doble Ary Connetling Arm Ling Hole for Wace sot \ CY Vs team Brackets. Center Weight Bell Bearing ie) Link Cellar Fin. Wr. Ba//. Link Co/lar. Ne, dle Sleeve 9 “i sehode- ted $f «— Orep Red Brass Head DY \) Va S Cress Bar. . tS Long Gov Fred Cov Dash Por Bressth I Ay Knock Off Lever. Gov. fe (Es ie - a Spindle Bal! Beering. w a Center Weight YN Pandilun Arm. Connecting Arm ofety Cam. Gor Dash Fe 4; (ae) Vetth Plate \ pceal\ ita! p55 ig ful Ss yoindle. Staem Hoek. al \ Che Gres3 Head Re Governor Orep Pod 7 aN Kw nm Drop Rod Arrn. Be// Crank Shof »\ ct Pp Safely Comes Ps) Ball Crank 0 “) \ Knock Off Cam Govarror Calica i a Short Gov Kod. be) Bell Crank Boering Collar: Spindle. Gov Dash For Cover: Gov. Dash Fort — Bobositt Dash Pet Plunger: Adjusting Plate a bbsTr. Smee! Gor Fulley. XS YK es: gs FIG. 25. METHOD OF HOOKING UP A GOVERNOR WITH CORLISS VALVE GEAR 4 Stand Suppor’. Mitre Gears. The governor and governor rods should next be ad- justed if they require it. Figure 25 shows a common form of Corliss engine governor with its connection to the valves, parts of the governor being cut away to show its construc- tion. As shown here the parts of the governor are in the position they will occupy when the engine is running at. normal speed. If the speed rises about normal, centrifugal force throws the govérnor balls farther from the center. This raises the cross bar, carrying with it the drop rod arm, and throws the knock-off lever on the valve stem so that the knock-off cams strike the steam hooks earlier thus causing an earlier cut-off. If the speed falls below normal, the knock-off cams are moved in the opposite direction and cut-off occurs later. 4] If the belt which drives the governor should break, the cross bar would drop to its lowest position and this would make cut-off come at the latest possible point in the stroke, or the steam hooks would not be disengaged at all so that the cylinder would take steam for the entire stroke, which would cause the engine to run away. In order to prevent that possibility, safety cams are put on the knock-off lever. When the governor falls to its lowest position, the governor knock-off levers are thrown around far enough to bring the safety cams under the steam hooks thus preventing the admission of any steam to the cylinder. If the safety cams are allowed to come into action as described above, the engine cannot be started after it is shut down until the governor is raised high enough to prevent the safety cams from coming in contact with the hooks. It would be a nuisance to have to raise the governor every time the engine is started so a safety device is placed on.the governor to prevent it from falling to its lowest position and bringing the safety cams into action when the engine is shut down by hand. Cut-orrs IMPORTANT IN MULTI-CYLINDER ENGINES Setting the valves on a compound or triple expansion engine of the Corliss type is precisely the same as for a single engine except that the adjustment of cut-offs in the various cylinders is largely a matter of “cut and try” until best results are obtained. This is usually considered to be at points where an equal load is carried by each of the cyl- inders. An increase of cut-off in the high pressure cylinder, while the initial steam pressure and the cut-offs of the intermediate and low-pressure cylinders remain as before, results in an increase of the pressure in the first and second receivers an increase in effective pressure in all three cyl- inders and consequently results in an increase in horse- power of the engine. Conversely an early high-pressure cut-off without change of the other cut-offs and initial steam pressure causes a decrease in receiver pressures, effective pressures and horsepower. Lowering the initial steam pressure in the high-pressure cylinder without change in cut-off results in lower receiver pressures, lower effective pressures and lower horsepower. 42 Conversely, if, under the same conditions, the initial steam pressure is raised, the receiver pressures, the mean effective pressures and the horsepower will be increased. Other conditions remaining the same, if the interme- diate cylinder cut-off is made later, the pressure in the receiver and the intermediate cylinder is less and the drop from the high-pressure cylinder increases, whereby the power developed in the high-pressure cylinder, owing to the increase in the effective pressure, 1s increased. At the same time the mean effective pressures in the intermediate and low-pressure cylinders decrease, hence the horsepower there developed will be decreased. The converse of this is also true. } EFFECT OF CHANGE IN LOW PRESSURE CUT-OFF Again, suppose that other conditions remaining the same the low-pressure cut-off is made later; then the pres- sure in the second receiver will be lower the mean effective pressure in the low-pressure cylinder, hence the horse- power there developed, will decrease. At the same time, the mean effective pressure in the intermediate cylinder increases, hence the horsepower there developed will in- crease but no change will take place in the high-pressure cylinder. If, under the same conditions, the low-pressure cut-off is made earlier, the horsepower developed in the low-pres- sure cylinder will be increased, that of the intermediate cylinder will be decreased and that of the high-pressure eylinder will remain unchanged. PoINTs TO REMEMBER IN SETTING CORLISS VALVES In general the setting of Corliss valves may be sum- marized as follows: 1. Remove the steam and exhaust bonnets and upon the end of each valve will be found a mark corresponding to the opening edge of the port. The direction for opening the valve can be determined by working the wrist plate by hand. 2. Examine the wrist plate hub and bracket. Upon the bracket will be found a mark corresponding to the central position of the wrist plate and two other marks locating the extreme travel of the wrist plate in either direction of motion. 43 3. See that the rocker arm travels equal distances each side of the vertical position. ‘To do this loosen the eccentric and rotate it slowly about the shaft. Then with a plumb bob and scale, measure the distance the rocker arm travels each side of its central position, and adjust the eccentric rod, to bring the distances equal. 4. Rotate the eccentric about the shaft and see that the wrist-plate travels equal distances each side of its central position as shown by the travel marks. If it does not, adjust the length of the reach rod to bring them equal. 5. Block the wrist-plate in its central position, then pull up the dash-pot rods until the hook pins engage with the steam hooks. Adjust the length of the steam and exhaust radius rods until the valves have the proper amount of lap as determined by size and speed of engine table. 6. Throw the wrist plate with the starting bar, first to one, then to the other extreme position and adjust care- fully the length of the dash-pot rods so that the steam hooks will latch with the hook pins when the wrist plate is at its extreme travel, allowing 35 in. for clearance. v7. Place the engine on dead center and see that the reach rod is fastened to the wrist-plate. The eccentric should then be turned in the direction that the engine is to run until the proper amount of lead is secured and the eccentric is then fastened to the shaft. Place the engine on the opposite dead center and measure the lead. If it is not the same, make it the same by adjusting the length of the steam radius rods. 8. Block the governor up half way in the slot and fasten the reach rod lever at right angles to a line drawn half way between the two rods. Adjust the length of the reach rods until the knock-off arms stand vertical; with governor in this position, turn the engine over until cut- off occurs and measure carefully the distance the crosshead has traveled ; place the engine so that the crosshead will be the same distance on the other stroke and adjust the length of the reach rod until the cut-off will just occur. 9. Drop the governor to its lowest position and see that the safety blocks on the knock-off cams are adjusted so as to prevent the steam hooks from latching with the hook pins. CHAPTER V FOUR-VALVE ENGINES S MENTIONED in the first chapter, the four-valve principle has been applied to engines using different types of valves. One development of the four-valve type has been the building of a valve gear similar to the Corliss “Frame Reach Sa : Roa, Steam Eccentric Rod. vFrame Reach i Rod, Exhaust Cylinder Reach Roa. Steam Wrist Plate:, vExhaustArm + of Rocker Arm-- Front Exhaust I El a Beg Rocker- ‘+ Exhaust Eccentric Rod a se, él Arm “Exhaust-Valve Link Rod's? Bracket“ Il- Elevation FIG. 26. NON-RELEASING TYPE OF CORLISS VALVE GEAR USED WITH BALL ENGINE tvpe but different in that no releasing mechanism ‘is used. Engines of the four-valve type have also been fitted with grid-iron valves and with poppet valves. One engine of the non-releasing Corliss type is the Ball, the valve gear of which is shown in Fig. 26. In setting the valves for this engine, the eccentric rod is adjusted so that the rocker arm travels equal distances on each side of the vertical position. The eccentric is then blocked up with the governor weight arm in its extreme outer position. In this position the center of the eccentric is in line with the centers of the suspension pin and of the shaft. Next the 45 engine is turned over until the steam valve at the crank end, moves as far towards opening as it will. If the valve does not come within s'; to 7g in. of uncovering the port, the reach rod connecting the rocker arm to the steam arm should be adjusted until the valve is in the position stated. SETTING FOR LAP When the engine is turned over until the head-end valve is moved towards its open position, the lap at the end of the valve travel should be 74 to 35 in. If it is not, the cylinder reach rod which connects the two steam arms should be adjusted. If this is done, the engine will not take steam when the speed throws the governor weight to its extreme position. An indicator is necessary to adjust the point of cut-off accurately for the two ends. The cut- off should be adjusted with the indicator so that it is prac- tically the same at both ends. As there is considerable wire drawing at no load, this should not be eliminated. The pressure before cut-off should be about half the pres- sure at the throttle. In setting the exhaust valve, the link connecting the two exhaust valve arms should be equal in length to the distance between the valve centers, for cylinder diameter of less than 19 in. Where the cylinder is more than 19 in. an exhaust wrist-plate is used and the exhaust valve link should be adjusted so that, when the wrist-plate is turned to bring the wrist-plate pin and the two link pins in a straight line, the exhaust valves should cover the ports with equal lap on both edges of the ports. EXHAUST VALVES SHOULD Have EQuaL OPENING When the engine is turned over, the two exhaust valves should open equally. If not, adjust the length of the valve rod until both port openings are equal. ‘The exhaust eccen- tric on the shaft is now moved so as to cause compression to begin at the desired point. This should be such that the compression pressure will rise to about half the throttle pressure. Head-end compression should be a little greater than crank-end. ‘The correct amount is the least compres- sion with which the engine will run smoothly. 46 FITCHBURG VALVE GEAR To set the valves of the Fitchburg engine (Fig. 27), first adjust all rods and connections so that the several parts will travel equally on both sides of the center in a complete revolution of the engine. As the engine has two eccentrics, one for the steam valve and one for the exhaust valve they should be set separately. Ignoring for the pres- ent the exhaust valves, place the latch of the steam valves in the center of the spiral block and clamp the hook by its lever, adjusting the movement of the wrist cranks by the =e = Uy) Pe Ve cS eg lil FIG. 27. FITCHBURG VALVE GEAR right and left connection as provided. Set the engine exactly on the dead center and move the small rod attached to the head valve in or out of its cam until the port is opened the proper lead, which is usually about 3g in. and tighten the set screws in the neck of the rod. Roll the engine on the other center and proceed as before. To set the exhaust valve, adjust for equal travel as usual and set the eccentric on the shaft so that the exhaust valve for each end will close the port when the piston is about 1 of the stroke from the end. It is best to spot all set screws to prevent slipping. SETTING VALVES FoR LENTZ HNGINE In the Erie City Lentz Engine the valves used are of the poppet type driven by eccentrics mounted on a lay shaft. These valves are of the double-seated balanced type. In Fig. 28 is shown the arrangement of the valve gear for this type of engine. An admission valve eccentric is used which has an oblong slot in it to permit side travel so that the action of the governor will change the point of cutoff. The exhaust valve eccentrics are fixed in definite 47 position but may be advanced or retarded to control the point of release and the amount of compression. In order to set the steam valve, the lay shaft is turned until the eccentric rod of the valve is at right angles with FIG. 28. VALVE GEAR OF ERIE CITY LENTZ ENGINE the driving block which is linked to the governor. If the governor is now opened and closed from maximum to minimum positions, the steam cam lever should show but a slight movement. This position of the eccentric is the one which it assumes when the steam valve is to open and 48 ANIONDT ZLNAT NI LAVHS AVI V AG NHAINA AUV SHATVA LaddOd LQG * — SSS 12) 2 ; =, ),, myn Ye 2) PU” ae MME LM “6% ‘DId 49 the valve stem or spindle should be adjusted by screwing in or out of its upper end so that the roller just touches the cam, and so that the movement of the eccentric raises the valve. This is the position of the valve with the engine on dead center. TIMING THE VALVES Timing of the entire valve gear is accomplished by shifting the bevel gear driving the lay shaft, one or more teeth. On the latest type engine, however, this is more conveniently accomplished by removing the bolts in the coupling flange on the lay shaft, located between the gov- ernor section and the gear section and moving the gover- nor section the desired distance and in the desired direc- tion, then inserting the bolts in the flange in the new position. ° Shifting the steam eccentric ahead causes the lead to be greater and cutoff earlier. Shortening the eccentric rod will likewise increase the lead and give a later cutoff. The adjustment of the exhaust valve is made by shifting the eccentric ahead to get earlier release and compression. Shortening the rod will give earlier release and later com- pression. ‘These valves are tram marked at the factory with a punch mark on the valve stem and on the roller guide or crosshead. ‘These marks are 2 in. apart. In case of removal and replacement of the valve, the stem length may be made as originally set by tramming this distance. CHAPTER VI SETTING AMES, CHUSE AND HARRISBURG VALVES N THE Ames unaflow engine, steam is admitted to the cylinder by a double beat poppet valve which is lifted by a roller in a square section sliding bar, when it comes in contact with the lifting cam. This cam is carried in a FIG. 30. SECTION THROUGH BONNET AND VALVE OF AMES ENGINE cylindrical bronze cross head attached to the valve stem and the valve is closed by the coil spring on the top of this crosshead, the top of the spring bearing against the bonnet eap. In Fig. 30 is shown a section through the bonnet and valve which is used for steam admission. ‘The exhaust as with all unaflow engines is through a center belt of ports. 51 When the engine is built for non-condensing service the piston has concave heads. ‘This provides enough clear- ance volume to reduce the compression pressure to a reason- able amount. PROTECTION AGAINST Loss oF VACUUM For condensing operation the piston has straight ends and the clearance is made as small as possible. In order to protect the engine, if the vacuum should be lost, an automatic by-pass valve is used such as is shown in Fig. 31. FIG. 31. BY-PASS VALVE PROTECTS THE ENGINE AGAINST HIGH COMPRESSION These valves are controlled by the condition existing in the exhaust belt of the engine. They operate only with loss or restoration of vacuum and do not operate with each stroke of the engine. The small pipe is connected with the exhaust belt or exhaust pipe of the engine, thus com- municating the conditions in the exhaust belt to the syl- phon which is attached to the valve stem. - By the action of the vacuum the sylphon is collapsed, the coil spring compressed and the valve held firmly to the seat, which reduces the clearance in order to secure proper 52 compression for condensing service. If the vacuum is par- tially or totally lost the spring will open the valve which connects a clearance pocket in the cylinder head with the clearance in the cylinder thus increasing the total clear- ance volume and preventing undue compression during non-condensing operation. When the vacuum is again restored, the valve closes as above described. It is possible to change the tension of the spring by adjusting screws, so that the point at which the valve opens and closes can be varied to a reasonable extent. ASSEMBLY OF THE AMES VALVE GEAR Assembly of the valve gear is made on the basis of tram marks on the rods and rod heads which have been marked at the factory. These marks are stamped upon the rods after the valves have been set and before the engine is dismantled on the testing floor. If the engine, for any reason, has not been tested before shipment, the rods will not be marked, in which case the eccentric rod should first be connected to the rocker lever and so adjusted that the rocker lever over the frame travels equal distances either side of the vertical center line. First adjust the valve stem so that there will be about 0.002 in. space between the flat part of the cams and the roller in the roller rods. ‘This space is conveniently meas- ured by using a thickness gage through the peep hole open- ing in the side of the bonnet. This space of 0.002 in. will be slightly increased as the valve stem expands when sub- jected to the steam temperature and should be about 0.003 in. when the engine is in operation. With the valve stems adjusted as above, place the rod over the frame in position as shown in Fig. 32, turn the engine to its crank end dead center and adjust this reach rod so that the roller in the crank end roller rod just touches the cam. Then with the engine on its head end dead center, adjust the ball rod over the center so that the roller in the head and roller rod will just touch the cam or about the same as the crank end. This is in the nature of a preliminary setting, only, and further adjustments will be necessary after the engine is In operation. In the illustration previously referred to, the controlled compression type of engine is shown. This 53 type of engine is used where it is desired to exhaust against back pressure of from 2 to 15 lb., where steam is required for low-pressure heating, drying or other purposes. CONTROLLED COMPRESSION In this case, secondary exhaust ports and valves are located directly at the ends of the cylinder so that the final exhaust closure is not controlled by the piston covering the eo — FIG. 32. CONTROLLED COMPRESSION IS OBTAINED BY ADJUSTMENT OF EXHAUST VALVE SETTING secondary exhaust ports. This construction permits of the compression being controlled at will, as it is possible to vary the time of the final exhaust closure to such an extent that any desired compression pressure may be obtained under widely varying admission. In setting the exhaust valves remove the covers on the opposite side of the cage from the rocker lever, which will allow a full view of the side of the cams, then turn the engine over in the direction of rotation until it is on its dead center, and make a mark on the side of the cross- head shoe and a similar mark on the crosshead guide directly in line with the one on the crosshead shoe. Turn 54 the engine to the other dead center and mark it in the same way. ‘This will provide for conveniently measuring the distance the piston may be from the end of the stroke. Turn the engine over until the piston is within 1 in. of the head end dead center from the expansion stroke and adjust the reach rod D shown in Fig. 32 so that the cam in the crank end cage’is just in contact with the roller. Turn the engine over until the valve is seated and measure the distance the piston is from the crank end. This will determine the length of the compression which should be approximately 20 per cent of the stroke in ordinary cases, and in any event will be close enough for preliminary set- ting. Turn the engine to the crank end dead center and adjust the valve rod E to open the head end valve in the same manner as the crank end valve. With the valves thus set, the engine may be operated and the rods further adjusted to gain the best results by using the indicator after the engine is in operation. ‘The roller in the small crosshead on the exhaust valve stem should be adjusted through the small rectangular opening on the side of the cage so that there will be about 0.003 in. space between the cam and roller at a point on the round part of the cam just before the lifting part comes into contact with the roller. EFFECT OF VALVE ADJUSTMENTS In Table II the effects of adjustments made on the exhaust rods and change in location of the exhaust eccen- tric on the shaft are shown. The exhaust valve gear is fully as sensitive to adjustment as the admission valve gear and only slight adjustment will have a pronounced effect on the indicator diagram. In order to set the valves more accurately, it is neces- sary to take indicator diagrams after the engine has been operated for a short time and is warmed up. Any adjust- ments to the valve gear necessary to change the valve set- ting should be made with a view of properly adjusting the crank end valve first, giving no attention whatever to the head end valve until the crank end valve has been satisfac- torily adjusted, bearing in mind that the valve motion is sensitive to adjustment and little change on rods is re- quired to make a material change in the indicator diagram. 55 With the crank end valve satisfactorily adjusted, the head end valve should be adjusted in the same way. It should be understood that, due to the angularity of the connecting rod and eccentric rod, it is not possible to obtain as good a diagram from the head end as from the TABLE II. CHANGES IN EVENTS DUE TO VALVE ADJUSTMENTS Adjustment of Steam Valves. ee Adjustment - feat [Atniosion | toot | Shortening reach rod A Later Lighter Earlier Heavier Lengthening reach rod A Earlier Heavier Later Lighter Shortening ball rods B Unchanged Lighter Earlier Heavier Lengthening ball rods B Unchanged | Heavier Later Lighter Adjustment of Exhaust Valves (Engines up to and including 30 inch stroke) Crank End | Head End in SA a es Valve Shortening reach rod D Earlier Later Later Earlier Lengthening reach rod D Later Earlier Earlier Later Shortening valve rod E Unchanged Unchanged Later Earlier Lengthening valve rod E Unchanged | Unchanged Earlier | Later Moving exhaust eccentric around the shaft in direction of TOTATLONecccccccccccccoee | Later Later Earlier Earlier Moving exhaust eccentric around the shaft in opp- osite direction of rotat- LOiNe ese lale'w ale.ele o.6's o ele e 60-6 0 Earlier Adjustment ‘Adjustment of Sxhaust valves (Engines 34 = inch to 36 - inch stroke) Crank ind | Head End Adjustment Valve pei votre ase Opens Closes | Closes Shortening reach rod D Later Larlier Later Lengthening reach rod D Zarlier Later Earlier Shortening valve rod 3 Unchanged Unchanged Later Lengthening valve rod E Unchanged| Unchanged farlier Moving exhaust eccentrics around the shaft in dir- ection of rotation....... | Zgrlier Earlier Later Moving exhaust eccentric G around the shaft in opp- osite direction of rota- ELON cecccccvcccccscsecce Earlier | Earlier crank end with a shaft-governed engine of any type. In most cases the lead will show later and the admission line will not be as good as for the crank end and, if there is any difference in compression, it will show higher on the head end. Various indicator diagrams are shown in Fig. 33 which will give a general idea of the type of diagrams from one of these engines. 56 CARE SHOULD BE USEp IN INCREASING LEAD Care should be exercised when increasing the lead on the valves with the engine carrying a load, that the lead is not increased so much that the governor will lose control of the speed when the engine is operating at friction load. This is quite possible, as the rollers may be adjusted so far under the cams with the engine carrying a load, that when the load is thrown off and the governor is on its minimum fads calor Diagrams F2°Or77 /77a'Cato eagraiis Fro UiaFlow Lr7gire. Controlled—-Cormi pvessior Unae-F/OowWw Ail Diagrams Taken ie Non Condensing Diagram Shows Lead, Late O17 The Head End. Non-Corden sing Diagram Shows Lead, Late On The Head End. Won-Condensisig Head Ya Nae ae Diagram Shows Lead, Late O17 THe Crank End ee Diagram Shows Lead, Late OnThe Cranh Erd 07. Condensing ee Diagram Shows Crank Ead Exhaust Valve Closes Too EFerly Cawsii7 wigh Compression On Crank End Correct Non- Condensing Diagram Diagram Shows Head End Exhaust Valve C1ESCS Joo Early Couvs/7g nigh Compression On Head End. Condens 171g Correct Condensing Diagram f Correct Diagram FIG 33. EFFECT OF VALVE SETTING ON INDICATOR DIAGRAMS 57 travel, the roller may still be coming in contact with the cams and lifting the valve slightly, admitting steam into the cylinder, causing the governor to lose control of the engine. In this case it 1s necessary to decrease the lead only to such an extent that the governor will control the engine at the friction load which is a maximum lead and should be given to the valve with maximum steam pressure. If the engine is to operate sometimes condensiyg and at other times non-condensing, the valves should be set for Rolle Sa A i eS is Roller slide — 4 ll E Cam Eko A aes nee Sp ere te Od Aes < Reach rod == Crosshead Balland socket _——— Sal CAE a —m iene 7 coe yee aus HCl YL Yes ii Yh ee f Sea sos . FIG. 34. CAM HEAD AND VALVE OPERATING MECHANISM OF CHUSE ENGINE the condensing operation as a condensing engine will not operate satisfactorily with as much lead when operating condensing as it will non-condensing, due to the action of the vacuum in addition to the early admission of steam. SINGLE-BEAT PoPpPpET VALVES IN CHUSE ENGINE In the unaflow engine built by the Chuse Engine & Manufacturing Co., admission valves are of the single-beat poppet type. It will be noted from the sectional view of this valve shown in Fig. 34 that the valve assembly con- 58 sists of a camhead, roller-slide, the valve and valve stem. The roller slide is operated by the rocker arm driven by the governor eccentric. ‘The roller slides under the cam and lifts the small crosshead that carries the valve stem and valve. In this construction, the valve stem is slipped through the center of the valve and is held in place by a screwed jam-nut. The upper end of the stem screws into a cross- head, which slides.in the valve bonnet and carries a cam. A roller is carried on the roller slide which reciprocates in the housing and the roller by lifting the cam opens the valve. The slide rod is fastened to the reach rod by a ball and socket joint and the reach rod in turn is fastened to the steam rocker arm. This arm is of the indirect type causing the reach rod to move to the right when the eccen- tric rod and eccentric move to the left. SETTING CHUSE STEAM VALVES To set the steam valve it is first necessary to locate the crank in center position and the reach rod is next uncou- pled and the rocker arm adjusted so that it travels equal distances from its vertical position. By uncouphng the ball and socket joint it is possible to disconnect the reach rod from the lower slide rod and the top half of the valve may then be removed. ‘This exposes the slide rod and cam of the valve stem crosshead. The slide rod should then be shifted to.bring the roller under the high or thin part of the cam. The clearance between the roller and cam should — be approximately 0.004 in. This clearance should be care- . fully checked by slipping a feeler gage between the roller and cam and the valve stem should be screwed in or out of the crosshead to bring this clearance to the value given, | if it is not correct. If the clearance is too small when the engine warms up, expansion may cause the valve to remain open at all times. After adjusting both head and crank end valves the bonnet should be replaced. The next step is to connect up the reach rod and place the engine on crank-end dead cen- ter. After this is done, the reach rod should be lengthened or shortened to give the valve a lift of 35 in. with the engine on dead center. To measure this lift a punch mark > 59 should be placed on the upper edge of the valve stem housing, at the part marked O in Fig. 34 and a second one on the valve stem locknut. This should be measured with the valve closed and when the engine is on dead center. After this is done the engine should be turned to the head end dead center and the rod A adjusted until the head end valve has the same lift or lead. Where the engine is intended to operate condensing, automatic compression relief valves are provided as a FIG. 35. AUTOMATIC COMPRESSION RELIEF VALVE safety device to relieve the excessive compression in case the vacuum should become too low or fail all together. One of the automatic relief valves is shown in Fig. 35. How CHusE RELIEF VALVES WoRK Considering the valve A closed for condensing opera- tion as shown, live steam is admitted through pipe D to chamber B. The excess pressure which holds the valve A closed is due to the greater area of the valve body in cham- ber B compared to the area of the port leading from the cylinder. ‘This difference in pressure is sufficient to hold the valve A closed under ordinary initial pressure in the cylinder. | 60 If the compression becomes excessive, due to the failure of the vacuum, the valve A is forced off its seat, opening the small valve C and throwing the chamber B into com- munication with the atmosphere. The large valve is then free to drop to the full opening, allowing free communica- tion between the cylinder and the auxiliary clearance chamber. The valve will remain open as long as the vacuum is below its safe limit. When the vacuum returns, atmospheric pressure under the valve will lift it as soon as sufficient vacuum is FIG. 36. AUXILIARY EXHAUST VALVES USED FOR NON-CON- DENSING OPERATION obtained. Thus the valve A will close and admit steam through D into chamber B which will again hold the valve in position for condensing operation. NON-CONDENSING OPERATION Where Chuse engines are designed for non-condensing operation, the same sort of admission valves and operating mechanism is used as on condensing engines. The auto- matic compression relief valves are replaced by auxiliary exhaust valves, located on the side of the cylinder at the end of the piston travel. These exhaust valves are operated by the same sort of cams and slide mechanism as steam valves, except that they are driven by a fixed eccentric instead of by the governor. Figure 36 shows the manner in which the auxiliary exhaust valves are located on the cylinder. Part of the 61 cylinder steam passes out through the center exhaust ports as soon as these are uncovered by the piston. The cylinder is then filled with exhaust steam at atmospheric pressure which is allowed to excape through the auxiliary exhaust valves until about 7/10 of the return stroke is completed. Steam flows from the ends of the cylinder bore through the passage A and passing around the open valve, enters the central exhaust pipe through the passages B and C. HARRISBURG ENGINE USssEs PISTON VALVES In the unaflow engines built by the Harrisburg - Foundry & Machine Works, central exhaust ports are pro- vided but, in place of the customary steam valve for each end of the cylinder, a single piston valve is used similar to the type used on high-speed engines. Another feature of this engine is the use of auxiliary clearance space. Figure 37 shows the action in diagrammatic form. In position 1, the piston is commencing its stroke, and the valve is just opening and admitting steam. Exhaust is passing to atmosphere through the central ports and emp- tying the auxiliary clearance chamber EGE. In the sec- ond position, the steam valve is open, admitting steam behind the piston and the exhaust valve is open at the opposite end. The central exhaust ports are closed and compression is beginning in the cylinder and auxiliary chamber EGE. In position 3, the piston is in the position of cut-off, the valve having reversed its movement, and the admission ports are closed shutting off the supply of steam to the head end of the cylinder. Expansion commences with the exhaust ports still open at the opposite end and compression continues in the auxiliary clearance chamber EGE. As shown in position 4, the outer edge of the valve opens the port at the head end, allowing steam from the auxiliary clearance chamber EGE to pass into the cylinder, mixing with the expanding steam and expanding with it until the central exhaust ports are open to the atmosphere. In the mean time the opposite end of the valve has closed the exhaust ports and compression occurs in the cylinder and cylinder clearance only. At position 5, the central exhaust ports are uncovered by the piston and the steam is exhausted reducing the pres- 62 sure in the cylinder and auxiliary clearance chamber EGH to exhaust pressure. At position 6, the stroke is completed and the piston is at the end of the cylinder ready for the return stroke. In this position the valve is opening to admit steam to the crank end the exhaust valve at the opposite end is still open and head end exhaust continues. For condensing engines, clearance pockets are provided, which are placed in communication with the cylinder by hand-operated valves, should the engine be required to run non-condensing. Ae USS as SESE RS Se SS | Position No. 5 ; Position No. 6 FIG 37. CYCLE OF OPERATION FOR’ THE HARRISBURG set ‘ENGINE 63 In Fig. 38 are shown the types of valves which are used in this engine. *They are the balanced piston type made with adjustable steam-packed rings and operate in remov- able cages or bushings. For the smaller sized engines the single ported type is used, while the larger engines are fitted with the double ported valve. SETTING HARRISBURG PISTON VALVES While the general method used in setting piston valves is apphecable to setting the valves of the Harrisburg una- flow, the procedure will be taken up detail. After the crank dead center has been located the eccentric rod is . 4 ! ae (e- “i a d FiG. oc. TYPE OF PISTON VALVE USED IN HARRISBURG ENGINE adjusted in length until the valve block to which this eccen- tric rod is pinned, moves equal distances from the center of the valve block guide when the eccentric is moved to the two extremes of its throw. After this has been done, the valve is disconnected from the block and drawn out of the steam chest. Templets of the valve and the valve bushing ports are made as outlined in the method for set- ting piston. valves. Templets of the valve and the valve bushing ports are made and the distance of each port edge from the face of the steam chest is measured by the measuring rod. The port dimensions, as well as those of the valve, are marked off from the point X, as shown in the Fig. 39. The valve templet is then shifted until it covers the head end and crank end steam ports by equal amounts, so that there will be equal laps. The distance from X to the valve templet is measured and replacing the valve in the steam chest end with the eccentric in mid-position, or the valve slide block at the center of its travel, the valve rod is adjusted until the end of the valve is the same distance 64 from the face of the steam chest as is the valve templet when set with equal laps. The governor weight should be placed in the normal position for full load conditions. The engine should be set on head and crank dead centers, and the position of the valve measured and transferred to the templet. If the valve has been set properly, the leads should be equal. After this is done the governor spring should be removed and the weight arms shifted to their extreme out- ward or no load position. The travel of the valve should — = 3 DA AAIII a ; WN SSS \ gee TZ. FIG. 39. MEASURING VALVE PORTS FOR TEMPLET be checked and referred to the templet to determine whether the valve uncovers the ports. If the port is uncov- ered, it will be necessary to remove the valve, and screw the ends together until the amount of lap is sufficient to keep the valve closed when the governor is at its outermost position. It is important that the compression be kept below the initial pressure by 5 to 10 lb., which can be checked by means of indicator diagrams. If it is desired to increase or decrease lead, this can be done by nuts on the valve stem where the valve heads are locked. ‘To increase lead lengthen the distance between valve heads and, to decrease lead, shorten this distance. CHAPTER VII HAMILTON, KINGSFORD, MURRAY AND NORDBERG VALVES @ NE point of difference in the Hamilton unaflow engine which is built by the Hooven-Owens-Rentschler Co. makes it rather distinctive. The steam valves are placed horizontal at the bottom of the cylinder as illustrated in Fig. 40. These valves are of the double-beat poppet type and seat in removable cages. They are driven by an eccen- tric operated by a lay shaft running alony the frame, which shaft is connected to the crank shaft by double gears and a drag crank. ‘The exhaust valves, which are on top the cylinder, are also driven by this lay shaft. In the steam valve the cam end of the valve stem fits into a crosshead X carrying a roller, Y. This roller makes contact with the cam, Z, which is clamped on the short steam cam shaft, W. This cam shaft is driven by the steam eccentric rod, O, by means of a rocker arm clamped to the steam cam shaft. Only one steam eccentric is used, the two valve cams being fastened to the one steam cam shaft. SETTING HAMILTON VALVES When settinz valves, the first step is to make sure that the rollers and cams are in proper contact. lf properly adjusted, the back of the cam is exactly vertical, when con- tact is made with the roller. Adjustment of the eccentric rod is then made, so that the distance from the center of the eccentric strap to the center of the stub end is 1% in. less than the distance from the center of the cam shaft to the center of the governor or eccentric shaft. This stub end is now connected to the cam shaft lever and the side shaft coupling is disconnected, so that the part of the lay shaft carrying the governor and eccentric is free from the portion geared to the engine shaft. After this is done, the governor is turned to bring the slide block at right angles to the eccentric rod, which is 66 determined by the fact that, when the position is reached, it is possible to move the governor in and out without moving the cam shaft lever. This is the lead position. With this engine is furnished a dial which may be clamped to the governor shaft and set to indicate the per- cent lead. If this dial is used, it should be set at 2 per Ehaust cam clamped to shart also set screw used.-*%- x Adjustable auxiliary Pe cecnns ee ‘eae valve stein wnee| we GER AN RAwwkee Are Fe ji a A Ses ee a SSN TUL LA = % zy (> sess Sam SSO . Asie } pee. PLL YZ ~ ri Auxiliary exhaust ‘ eccentric i) Ef, SS ZEZZIZZLLIS /Y eccontric eccentric \ 6 ea SF Ni SN Sn S Governor shaft Annannnn SSS CEES Z vs ofa. 2 me a { Zea WSS eth < 7 yA ve || mM : ES a : AD H =, ial FIG. 40. HORIZONTAL VALVE USED WITH HAMILTON ENGINE cent lead. If the dial is not available, marks can be made on the shaft and bearing. Revolve the shaft one-half turn and the other cam should just begin to push its roller at 2 per cent lead. This should be the condition when the governor springs are removed and the weight blocked half way out. When the governor weights are at the extreme outer position, the valve should not be opened at all by the cam. When the weights are entirely in, the maximum opening and cut-off are obtained. 67 In this engine, the cut-off and openings are equalized by changing the length of the eccentric rods and the lead is changed by shifting the governor shaft coupling so that the eccentric is advanced with reference to the crank pin. When the engine is tested at the factory, a mark is made on the coupling opposite the pointer mark on the bearing and stamped “crank-end center.” The shaft is then turned a slight amount until the dial shows crank- end lead and another mark is placed on the coupling and lettered “crank-end lead.” These two marks make it pos- sible to check up the valve setting at any time. Where the engine is to be used for condensing opera- tion, it is fitted with auxiliary exhaust valves placed at the top of the cylinder. These valves are of the double beat type and are controlled by cams fitted to a short cam shaft along the cylinder top, which is driven by a single exhaust eccentric from the main layshaft. RELIEF VALVES FOR CONDENSING SERVICE Where the engines are used for condensing service, relief valves are placed at each side of the cylinder and communicate with a clearance belt or passage around the cylinder. If it is desired to run non-condensing, these valves are opened by hand and add the auxiliary clearance volume to the normal cylinder clearance. When setting the exhaust valve, the exhaust eccentric rod should be disconnected from the camshaft rocker, and the exhaust cam should be adjusted for quiet operation by screwing down the cap nut on the end of the exhaust valve stem, until the valve is too short. The nut is then grad- ually screwed up until the noise disappears, although a precaution should be taken that the stem is not left too long. The eccentric rod is then reconnected and the cams are set by shifting the exhaust eccentric to its position of minimum travel. Next the governor shaft is rotated until the exhaust cam shaft is at one extreme of its travel, and the proper cam is set to bring its flat side level or horizontal. After this it is necessary to rotate the governor shaft about one- half a revolution or until the other extreme of the cam shaft oscillation is reached. Then the second cam is clamped with its flat side level. The check on whether the 68 proper setting has been made, is to turn the governor shaft through an entire revolution. If the exhaust valve does not open, the setting has been properly carried out. When the eccentric is shifted to any position other than that of least travel, both valves should have equal lifts. This exhaust valve gear is so designed that the valves open at about 6 per cent of the stroke past dead center and may be adjusted by the hand wheel to close at any point in the exhaust stroke up to 95 per cent. The lead is always constant. === { TN \ BN 8 a [TI SHS oe Lie, Ws Vi NZ SSSSSAG SMA FIG. 41. VALVE GEAR OF KINGSFORD ENGINE Set the engine crankpin on the crank-end dead center, rotate the governor shaft until the index of the bearing shaft coincides with the line marked “crank-end center” on the coupling and clamp the coupling. This completes the valve setting. KINGSFORD UNAFLOW ENGINE Figure 41 shows a cross-section through the valve gear of the unaflow engine built by the Kingsford Foundry & Machine Works. ‘This view shows the crank on the head- end center with the active part of the head-end steam cam and crank end exhaust cam about to engage in the open- ing of their respective valves. Similar conditions, apply 69 with the crank on the opposite or crank-end center. The location of the keyways in the cam shaft (steam and exhaust) and lay shaft for the eccentric and governor are determined from the valve diagram. To set the cams so as to give correct timing of valve opening is a simple matter, and the general procedure is as follows: Place the engine in any position off center so that the inactive part of the cam face engages the roller (steam or exhaust). Give the steam valve tappet about 0.006 in. clearance and the same clearance for the exhaust, measured by slipping a feeler gage under roller B and making adjustment at C. The next step is to turn the engine over and place the crank on either center. To simplify matters, we will place the crank on the head-end center and follow the points of adjustment from the drawing which, as previously men- tioned, shows the position of cams with crank on head end. For good running conditions 0.003 in. clearance be- tween cam face and roller is sufficient. Try a 0.003 feeler between steam tappets at A and, if this space is greater, slack nut on eccentric pin D, and with a small wrench on the square head turn the cam clock-wise until the 0.003 feeler pinches at A. This completes the setting of the steam cam. Give the exhaust cam the same clearance and proceed in a like manner with crank on opposite end. The final valve adjustments should of course be made with an indicator. For control of the steam valves, a centrifugal inertia governor is used, mounted on the lay shaft and equipped with two eccentrics, primary and secondary, which com- bination is dead beat. The primary eccentric is keyed to the lay shaft and the secondary is connected to the governor weights by means of links. This combination of double eccentrics is also used for the exhaust valve drive with the secondary adjust- able to vary the compression. Murray UNAFLOW ENGINES As will be noted from Fig. 42, the unaflow engine built by the Murray Iron Works Co. utilizes the poppet type of valve. These valves are of the double-beat type with the 70 lower valve seat attached on the valve body, while the upper valve seat is a light flexible steel disk held to the valve body by set screws. It is stated that the use of one flexible seat reduces the possibility of steam leakage, which exists when the entire valve is made in one piece. The upper valve disk rests on a seat turned on the head casting, while the lower valve edge rests on a seat that is a separate casting held to the cylinder head by a cap screw. Referring to Fig. 42 the valve rod marked X is driven by the governor eccentric and to this rod are fastened two 8 a ap EADS Yy. Wis. A = ia ow) ) | --— ta INT] @ — a lags FIG. 42. VALVE ARRANGEMENT OF MURRAY UNAFLOW steel blocks A, one to slide in each valve bonnet. Hach block carries a roller which makes contact with a cam block B, placed on a crosshead fastened to the valve stem. ‘The roller C, due to the reciprocating motion of the valve rod, makes contact with the cam B raising the valve stem and so admitting steam to the cylinder. When the valves are set, the engine is turned over until the roller C is under the flat surface of the cam D. The valve stem is then turned until the clearance between the cam and roller is 0.002 in. which insures that the valve will be closed when its roller is under the flat surface of the cam. 14 ADJUSTING MuRRAY VALVES FOR LEAD Lead is adjusted by uncoupling the valve rod X and setting the eccentric rod so that the rocker arm travels equal distances each side of its vertical position. This reach rod, X, should then be adjusted to a length such that, when the engine is on crank dead center, the roller just touches the cam of the crank-end valve. Next the rod Z is adjusted by the turn buckle, Y, so as to cause the head-end valve roller to touch its cam, when the crank is at head-end dead center. This engine also uses auxiliary exhaust valves, which are of the solid piston type and are moved by a fixed eccen- tric, through a linkage as shown. In order to set the auxil- iary exhaust valves an opening is provided into which a relief valve is screwed so that the engineer can see the auxiliary port slot through the exhaust valve cage. The valve is set so that the top edge is in line with the lower edge of the slot when wide open; that is, the valve opens wide without any over travel. When closed, the lap is prac- tically one and one-half times the length of the slots. This is necessary in order to keep the valve closed during half the engine’s revolution. After setting the two auxiliary valves so that their travels and positions are as near alike as possible, by changing the valve stem and reach rod length, the exhaust eccentric should be shifted to give a small amount of lead with the engine on dead center. If the valves do not show the same lead, correction may be made by adjusting the rocker arm to get equal travel each way from its vertical position and by changing the length of the reach rod. As in other types of engines, it is recommended that final adjustment of all valves be made, after the engine has been run awhile, by taking indicator diagrams. Auxil- lary exhaust valves must be set to give correct compres- sion for the existing back pressure and, when operating condensing, the auxiliary valves are uncoupled or left off entirely. In this engine the cylinder body is not steam jacketed but is covered with several inches of insulating material. Steam is admitted to each cylinder head through a cast- iron pipe connection and the cylinder heads are steam ANIOND MOTAIVNA Vv Ao NOILVTVIVISNI TVOICAL "OE ‘DLT 73 jacketed, the faces forming the steam chest for the engine. In this way condensation is reduced to a minimum. NORDBERG VALVES DRIVEN BY LAYSHAFT in Fig. 44 is shown the valve arrangement of the una- flow engines built by the Nordberg Manufacturing Co. As shown in this sectional view, both the steam and exhaust valves are driven by means of a lavshaft upon which the oe a4 NY “ap i ¢ somo ot \ TOCA A a WA NSS Sas & | SULT Ts eeeoue A Ge w 8 & y N N N N NY soy 3 4 % edt FIG. 44. NORDBERG VALVES ARE PLACED IN CAGES eccentrics are placed and which is driven by the crank shaft through bevel gears. A centrifugal type of governor, connected to the steam eccentric by a sleeve, controls the engine speed by altering the eccentric travel and the lift of the steam valve. | Valve action is obtained by the use of cams. Both the steam and exhaust valves are arranged in cages which set into the cylinder casting. Referring to Fig. 44 both steam and exhaust valves are operated by a cam lever which is actuated by a cam and rollers. When eccentric rod H moves upward, the cam X is rotated inwardly. This cam makes contact with the 74 opening roller and at the same time the back part of the cam X which is depressed comes under the closing roller Y. ‘The steam reach rod H, as it moves upward, causes the cam to push the roller D upward and the cam lever A moves about the fulcrum pin W. This causes the valve to lift off of its seat and admit steam to the cylinder. As the eccentric continues on around its circle, the operation is reversed, and since the cam has a steep slope at the points of contact with the roller, opening and closing of the valves are rapid. When the valve seats, further travel of the cam causes the valve stem to compress the valve spring, insuring posi- tive valve closing and also exerting downward pressure on the valve when it is seated. ‘These cams carry two marks, one showing the exact point of closure of the valve and the other showing the point where the connecting spring first comes under full compression. CaM AND ROLLER CLEARANCE When setting the valve, the fulerum D of the cam is turned eccentric so that the cam can be adjusted with the proper amount of clearance between the cam and roller. As in other valve settings which have been described, this clearance is about 0.003 in. In adjusting the length of the valve stem, care must be taken that the compression of the spring does not become excessive. In making this adjust- ment, the engine should be turned to a point where the valve is closed and the stem then adjusted so that the coils of the spring are not forced together so much that contact is made between the coils. The actual valve setting is carried out along lines which have been described. First the engine is turned to dead center, the governor weights are blocked in the outer- most position and the eccentric rod is adjusted so that the valve is not lifted but remains seated. In this case the cam should clear the cam lever roller. PROVISION FOR NON-CONDENSING OPERATION In order to take care of either condensing or non-con- densing operation, the exhaust cam is made with excep- tionally long contact faces so that, when operating con- densing, the valve can be kept closed and the rollers kept 75 in contact with the cam while the eccentric is giving the full stroke to the cam. The opening point of the exhaust valve is not so important but the point of closing must be set according to the operating conditions desired. This point of closing of the exhaust valve is changed by changing the effective length of the exhaust eccentric rod. This is done by introducing a combination lever M, which is car- ried by a rocker, the rocker arms for both the exhaust valves being adjusted by means of one hand lever. This adjust- ment can be made when the engine is in operation. By placing the hand lever in different positions, the point of closing of the exhaust valve can be changed as desired to fit any operating conditions. CHAPTER VIII RIDGEWAY, SKINNER AND WORTHINGTON VALVE SETTING DMISSION valves of the unaflow engines built by the Ridgway Dynamo & Engine Co. are of the double- beat poppet type and are placed in the cylinder heads. In order to compensate for slight variation in vertical dis- tance between the upper and lower seats, such as might be caused by expansion due to temperature changes, the upper lip of the valve is made thin enough to have slight flexi- bihty. The steam pressure above then aids in forcing the valve tightly on both seats and steam leakage is prevented FIG. 45. ADMISSION VALVE OF THE BIDGEWAY ENGINE 77 Motion from the governor eccentric is transmitted through an operating rod on the top of the bed, to the ram passing through the upper part of the valve bonnet. This ram carries a hardened and ground steel roller which, coming into contact with the cam above it, raises the stcel sleeve to which the valve rod is connected, and in turn lifts the valve. Figure 45 shows the construction of the valve and lifting mechanism and the means provided for adjusting various parts. The valve stem passes through a Lee oy i 4 I 4 4 Uy a ao YY =f Mii 7 Go by YY Ve A 4 hye yy yw 4 wy OY! Uh, Mi =, Wy yg Iie OSA os , y fi o x FIG. 46. RELIEF VALVE USED IN CONDENSING SERVICE long guide or stuffing box. A series of grooves is turned on the stem and these grooves, becoming filled with water, form an effectual seal against steam leakage. ARRANGEMENT FOR CONDENSING SERVICE Engines built for condensing service have an auxiliary clearance space in each head. The connection to this space is through a combination drain, relief and clearance valve, a section of which is shown in Fig. 46. The large hand wheel opens the connection to the clearance space and the small wheel opens the drain. Between these valves is a spring-loaded relief valve which can be adjusted by an outside nut. When the engine is operating condensing, the clearance valve is closed. Should the vacuum fail, the relief valve will open to pre- vent excessive pressure, until such time as the clearance 78 valve can be opened by hand, under which condition ample clearance space is provided for non-condensing operation and, at the same time, the relief and drain portions of the valve function as before. Engines designed for non-con- densing service only, have pistons with concave heads to provide the volumetric clearance necessary to prevent excessive compression. ARRANGEMENT OF RIDGEWAY VALVES In Fig. 47 is shown a sectional view of the cylinder which gives an idea of the arrangement of the valves. bo Hh ; af NZ2 a : \ Van MI = || 1 - ) KA or AG Ee Sal ie Lida . SI yb isan He SS |} ae ae, wn Eye eS im: Vail ase SOW EE y N RY AY Ny N N N N N N N N Ny FIG. 47. VALVE ARRANGEMENT IN THE RIDGEWAY ENGINE Referring to this figure and the previous illustration show- ing the section of the steam admission valve, the operation of the valves is as follows: The reach rod C is operated by the governor-controlled eccentric, the motion being transmitted through an eccentric rod and rocker arm, through the cam rod B. The roller C which is a part of the cam rod B comes in contact with the cam D and operates the valve. Setting the steam valve is a procedure quite similar to that followed in similar types of valvespreviously described but will be reviewed briefly. The reach rod D is first dis- _ 79 connected, and the length of the valve stem is adjusted to give a clearance between the cam D and the roller C of 0.002 in. when the roller is under the thin part of the cam. This clearance must be kept small as, if it is made much greater, there will be a pound when the roller strikes the cam while the engine is running. ReacH Rop ADJUSTMENT After reconnecting the reach rod to the cam rod B, the engine is turned over until it is within 1 per cent of its stroke of reaching crank dead center. ‘This is the lead point and the reach rod C should be so adjusted that the valve will start to lift at this point. In a similar way the FIG. 48. EXPANSION RINGS PREVENT LEAKAGE IN SKINNER VALVES engine is turned over in its running direction until within 1 per cent of the stroke, of head dead center. In that posi- tion the head-end steam valve is set to cause the valve to start to open. This adjustment is made by altering the length of the tie rod connecting the two cam rods. This tie rod has right and left hand threaded ends so that it is easily possible to change the distance between the cam rods. As in other engines, it is recommended that the engine be run for a time and indicator diagrams taken. If the lead is not correct, the proper change in timing should be made. It is also advisable to check the cam clearance when the engine is hot, as the engine will take steam for the full stroke unless there is some clearance between this cam and its roller. 80 SKINNER UNAFLOW ENGINES Unaflow engines built by the Skinner Engine Co. utilize a steam valve of the double-beat poppet design. This valve also is of a design which eliminates leakage due to unequal expansion of the valve and cylinder head. Figure 48 shows how the top portion of the valve is sep- arated from the valve body and is held down by spring tension. Expansion rings shown at A prevent steam leak- age between the two parts of the valve as any inequality of ¥. | 4 2 r fe. FIG. 49. VALVE MECHANISM OF THE SKINNER ENGINE expansion of the valve is compensated by a slight displace- ment of the upper part of the valve body. Figure 49 shows how these valves are set in the cylinder and also the actuating mechanism which is used. In this arrangement the steam valves are operated by a bell crank marked X. This crank carries a roller which makes con- tact with the cam Z which is a part of the rocker W. Movement of the rocker is obtained by the movement of the reach rod, O, from an eccentric which is controlled by the governor. PROCEDURE IN SETTING VALVES Valves of this type are set by blocking the governor weight in its outermost position as this is the over-speed -~ 81 position of the governor. When the governor is in this posi- tion, the engine is turned in the running direction and the reach rod and cam rocker W are adjusted until the cam just fails to open the valve. This prevents the engine from taking steam when the governor is in the over-speed position. Next, the steam valve is lifted by the end of the rocker X touching the set screw Y. When the engine is turned beyond the cut-off position, there must be a clearance between the end of the rocker and set screw, so that the =| al =! Al ul LILLPLL A i fe bi i 7777 i FIG. 50. AUXILIARY EXHAUST VALVES OF SKINNER ENGINE valve will be held open. Clearance at this point should be about 0.003 in. When the set screw has been adjusted to this clearance the engine is turned to crank center. Then the governor is blocked in its usual running position and the valve reach rod is adjusted so that the rocker X just makes contact with the set screw Y when the crank is on dead center. After this is done, the engine is turned to the head-end dead center and the reach rod is adjusted so that the rocker X just strikes the set screw Y on the head-end valve. The valves are now correctly set, although as a precaution it is well to block the governor again in the extreme outer 82 position and check the clearance between the cam and the rocker. AUXILIARY VALVES In Fig. 50 is a sectional view of the auxiliary exhaust valves which are used with the Skinner engine. In setting these valves, it is necessary that the eccentric rod be of such length that the rocker arm to which it is attached will move the same distance from its vertical position, when the eccentric is moved to its two extreme positions. The next step is to determine the lift of the valves. This is done by removing the covers from the sides of the exhaust cam boxes after draining out the oil. Chalk is then rubbed on the sides of the cam shifter A, which is under the exhaust valve stems B, and a vertical line scribed © on it, in line with the valve stem. With the calipers rest- ing on the inside of the bottom of the exhaust-cam box, . scribe a line on the side of the cam shifter when the exhaust valve D is down on its seat in a closed position. After this is done, turn the engine and scribe a line on the side of the shifter when the valve is in its topmost position. The difference between these lines represents the lift of the valve which should be as follows: Engine Stroke Lift of Valve 15 no A ee ee 5@ in. 16 D's soy hae een fee ee 5@ In. AB IN nS is eC peo cnt cee ee 34 in. PAU rea ert ge AR 34 in. Pak Cae Re E Mee eee et 43 in BA. | AD pou schon wit ns east pe a ee 43 in PLS MM ee SO aR ee 42 in BO. 1s si1) oe spcemlaleus ahg§s stn tn Dee eae en Lowe BO) ADL 2 io oie :otnisn: nl Tun do SGA ib dee et yes | It is possible to regulate the valve lift by movement of the exhaust reach rod, which has right and left hand threads. In making the adjustment the crank-end valve should be adjusted before the head-end valve. When the exhaust valves are closed, the end of the stem should clear the shifter by the thickness of an indicator card. In check- ing the wide open position of the valve, it is well to make sure that it is not striking anywhere, at its extreme normal lift, by opening it a little farther with a lever. 83 SHIFTING THE ECCENTRIC When the rods have been adjusted for proper lift, the time of opening and closing may be regulated by adjusting the eccentric on the engine shaft. It should be shifted so that the crank-end valve will close just before the pis- ton reaches the crank end of its stroke. When it has been set in this position, the crank-end valve will open imme- diately before the piston reaches the head end of its stroke. In a similar way the head-end exhaust valve should be checked to close just before the crank is on the near dead center and to open before the crank is on the far center. It will be found that the eccentric is marked on the side toward the engine bed corresponding to a mark on the shaft which shows the setting made at the time the engine was under test at the manufacturer’s shop. In large engines of the Skinner type, a slight change is made in the type of valve gear which is used. Although the valve itself is identical with those shown, the cam rockers are mounted on a shaft running along the cylinder which is driven by a linkage from the governor eccentric. The face of the valve cam is also made wider so that the valve-lifting lever and roller slide along the face when the cylinder expands on warming up. The method of setting the steam valve is the same, however, as for the smaller engines, WorTHINGTON UNAFLOW COMPRESSOR Valves in the unaflow engine-compressor which is built by the Worthington Pump & Machinery Corp. are set horizontally in the bottom of the cylinder head as shown in Fig. 51. These valves are of the double-beat poppet type. The cast-iron valve body M slides on an extension O of the valve bonnet. The valve rests on the cylinder head casting and carries seat R which is a light steel ring shrunk onto the valve body. This ring is somewhat flexible and it takes care of the difference in expansion of the cylinder head casting and valve body. It will be noted that the valve stem has a spiral groove in in it. Oil passes along the groove to the end of the | valve and so lubricates the valve stem and sleeve. Operation of this valve is due to the rotation of a lay shaft geared to the crank shaft. Two cams, one for each 84 cylinder end are fitted to a cam shaft, which is engaged by the lay shaft by means of a feather key. One of these cams is shown in Fig. 52. The rotation of the lay shaft causes the nose of the cam to strike the cam lever roller, which is connected by a link X to the valve lever Y. The motion of the cam is thus transmitted to the valve which is lifted off the seat and steam is admitted to the cylinder. At Z is the valve tappet which is engaged by the cam lever Y. It will be noted that the governor fits directly over the governor box and is driven by means of double gears from Ji Steam a der head, / jacket ee ee a “Relief valve connectioir FIG. 51. HORIZONTAL VALVES ARE USED WITH WORTITING- TON ENGINE the lay shaft. As the engine drives a compressor, there is also a pressure governor mounted on the base plate between the cylinder housings. This governor is of the diaphragm type and the discharge air pressure operates a small pilot valve which in turn admits liquid pressure to the operating piston. Movement of the piston is trans- mitted through an adjustable rod to a push pin which, pressing against the bell crank, moves the cam shaft. When the compressor is operating below the discharge pressure for which the governor of the engine is set, the engine will run at maximum speed for which the speed governor is set. As soon as the air pressure reaches the desired maximum, a bell crank shortens the cut-off and slows down the machine. | In engines of the duplex type, that is with two parallel cylinders, two sets of cam rockers are provided for each 85 cam, as shown in Fig. 52. This shows how the valve rod connection is made to the opposite cylinder. The main engine cranks are set at 90 deg. and the rollers in contact with the head-end cam are spaced at 90 deg. as are also the rollers of the crank-end cam. The cams are keyed to the shaft at 180 deg. FIG. 52. VALVE OPERATING MECHANISM Since the setting of the four steam valves is fixed in this way, the only valve setting necessary is the exact posi- tion of the bevel gear on the main engine shaft, as the position of this gear determines the lead or admission. The lead should be such that the steam valve is 35 in. open when the engine is on each dead center. It is advisable to determine the exact position of this gear by the use of an indicator. The lobe of the cam is tapered so that, with the speed governor in its lowest pos- 86 sible position, the cut-off in each cylinder is approximately 50 per cent, while with the governor in its highest possible position, the cut-off is zero. As the admission side of the cam lobe is a straight line parallel to the axis of the cam- shaft, the same admission point is maintained regardless of cut-off. The back or cut-off part of the cam is tapered so as to give the range of cut-off as stated. Clearance of the valve tappets should be about 0.002 to 0.003 in. when the engine is warmed up. This adjust- ment is made by changing the length of the valve rod X and the amount of clearance can be determined by insert- ing a thickness gage between the tappets. This clearance should be checked when the roller is on the base circle of the cam and not on any part of the lobe. If the clearance is not correct the valve will be noisy, will have insufficient lift or will remain slightly open at times resulting in a loss of economy. Although no auxiliary exhaust valves are used with this engine, it is built for non-condensing operation by the use of clearance chambers which are attached to each of the heads. These clearance chambers are opened by means of hand-operated valves which throw them into communication with the cylinder. When the engine is built primarily for non-condensing service, the required clearance volume is secured by making the face of the piston concave. CHAPTER IX GOVERNING THE ENGINE OWER developed by an engine may be altered by changing either the initial pressure or the point at which the engine cuts off. In the former case the area at the top of the indicator diagram, as shown in Fig. 53, is reduced, while in the latter method the expansion area is reduced. - THROTTLING OR VARIABLE CuT-oFF USED Governors operate on one of these two principles, although the throttling type is uneconomical since the steam is developed at high pressure and used at a lower oe . |. Throttli (A) Throttling (B) Variable Cut off FIG. 53. CHANGES IN CARDS CAUSED BY TWO METHODS OF GOVERNING pressure, thus cutting down the possible efficiency of the cycle. For this reason the use of governors for larger engines has been mostly confined to the variable cut-off - type. For varying the cut-off two methods are used; that of detaching the valve from the eccentric and closing it by a spring or dash pot and that of shifting the eccentric so as to alter the lead or travel or both. In the first method, the governor controls the point at which the valve is released from the eccentric and in the second method the eccentric is either turned around the shaft or is swung across the shaft on a pivot pin. As the detaching governor acts only on the cut-off, it alters no other event in the valve operation. While this has certain advantages, the type of mechanism used limits 88 it to low and medium-speed engines. If the eccentric operating the main valve is turned about the shaft, all of the events of the stroke are changed. It is desirable that the exhaust and compression be altered but little, hence this type of governing has to be designed with that point in view. It is well adapted to control riding cut-off valves through a separate eccentric, the main eccentric being fixed. It is possible to pivot the swinging eccentric so that it will increase the travel of the valve and thereby lengthen the cut-off and, at the same time, it may increase or decrease the lead at the will of the designer. As a matter of fact it is desirable to have the lead decreased as the cut- off is shortened, in order to avoid over speeding the engine at no load. Increasing the travel gives earlier admission, later cut-off, earlier release and later compression, Lead may be altered to bring all the events a little earlier or a little later, the former being generally used. Decreasing travel results in an opposite effect on each event of the stroke. Two TyprEs oF GOVERNORS There are two main types of governors in use, known as the fly-ball and shaft governor. In most Corliss engines the flyball has the centrifugal force of the balls working against gravity, but for higher speeds or more sensitive regulation or for other than vertical positions the spring is substituted. Although the details of shaft governors vary widely, they may be classed as two main types; those which use centrifugal force only and those in which this effect is combined with inertia. As a rule the centrifugal gover- nors are used where the eccentric is revolved around the shaft, controlling a riding cut-off valve. For controlling the valve of a single-valve engine, power is required which means a heavy governor weight and it has been found best to take advantage of the inertia of this weight to increase the quickness of action. In any form of shaft governor, changing the spring attachment changes the sensitiveness and changing the weight adjustment changes the speed. In the centrifugal form, increasing the spring tension and the weights will 89 increase sensitiveness or attachment of spring or weights may be changed so as to give them greater leverage about the pin, which has the same effect as changing the tension | or weight. ACTION OF FLYBALL GOVERNOR In Fig. 54 is shown a flyball governor of the type used on Corliss engines. This governor has an automatic safety Sty SSS NARA WAARARAARAN RRR 4 g « } m—as| FN 7 eS yay ANZ Vee . ze | Gy GUM Wits Uline 4 FIG, 54. ONE TYPE OF FLYBALL GOVERNOR USED WITH CORLISS ENGINES stop and when the engine is at rest the lever 4 rests on the automatic rest 5. This automatic rest is held in place by. the rod A and the arm 3 which is connected to the idler pulley, 2, resting on the governor belt. Should the governor belt break, the idler pulley will drop down pulling the automatic rest 5 from under lever 4 and allowing the lever to drop far enough to bring the 90 quoley -jIp uorptsod yung surjei0d [njiomod 91qBqs 0} A[PxI[T e1oP | -doO JOUIBAOYH | 889] JOUIOAON | 91OUI IOUIBAOY) oules 94}? eq Avur peeds ours yduoid SAT}ISUOS | -Ud ‘QaT}ISUas O1OUI IOUIBAOY | J9}SBj OUISU | VIOUI IOUIOAOYN | SSeT JOUIBAODH po. wor}1sod Jou | dolp louiss08 pepsor Alt -I2AO0S UdAIS | 0} —poeyoezye | -Avdy SSO] pus [10 199431] 10 | Io} Butusdo | JeAoT JO sn | J9MO[S UIATIP Sutuedo s9Z1eq | ea[BVa SsverOU] | -Iped osvoroagy |LOULIADDH que -I9HIp uwOrjIS quny | -od Zurje1sdo [uytomod | juny 0} AjeyTT] 0} APY ssay | IO WUIAAO 4 | C10UW JOUIIAON | 210W JOMIIAOY | 9eules 94} 9q Au peeds ours ysissnqjs “ud ‘dAT}ISUOS 91IOW IOUIBAOY @ATPISUOS uor}isod 100 poi |popsoy ATIAveyq [IO | -taA0oS udats |doip 0} peyou, | 910M pues JaIAvey IO Sut | JoJ Zutuodo |-ye Jsaey jo | 194sey} ueATIp -uedo sayjeurg | aayea asvoiooq | snipeiesveivuy |LOULTXADH aseyuly eBBIIATT ee pues psoT go cones cl ul dn-ayey, | JOMOIS OUISU | SSA JOUIAAON | e10UI JOUIaAODH = LS RE alae CIS Ie AEE sate, BE at | SAT}ISUGS SAT}IsSUes [OJOW JOUIZAOS sso Ap}ySyS | ‘reysey ous azyeVIqiA | JOUIeAOS pOT | -ue ‘IoUIaZAOZ 07 APEX CLOW | F4F1OM =F | POPBOT YM "820099 JOT1O ystsanjs “ssoq ‘{nyiomod q4duoid sso] Jou19A03 peeds ours @1OUI IOUIZAOY | JOMOTS OULsU | e[duIS soy |-GO sosvaerouy |***y09ye Urey OZIS PROT FYSIOM 103 io Avyjnd jo yisd 10 S][@q | USATIP eSBoI0 Il@ Joy sutids Ppso] IO uors JO ¥4310M |-ur JO Sur d 94N71IZSQng|-usz osvoI09q |9 8 B91 | -AUp osvatoeg {******esueqD @AT}ISUGS B1OUI DAT}ISUBS SSOT Apysys sou |1l9MOTS souls OYIqIA |-JaAOS ‘peor | -uo ‘10UI9AO0d 0} A[OHTT SssoyT |QyUsTIOM YA |PIPBOT YIM **sqooye 10YIO ysissnjs e1oul 4nq [Nj -19am0d 9J0UL ysisan{s 1oul0A03 peeds suis @IOW IOUIBAON| 10488} OUIsUTY | o[dUIIS soyep | -Ud sosvelodq |***JIHo ulepy 9ZzIs 103 10 Aat{nd Jo 41ed Jo [[@ USATIP osBaI0 JO} peo, IYZIeM | pO] JO UOTS s][vqjo |-op Jo Sut 2INFIZSQGNG | -ua} osveIdUT |FYSIOM osvesdU] | -ALIP osvoroU | ****** OBueYD: po, Sutds Sutids 10} JYUSIOM VSuBYH | UOIsue} sulIdg bE Peer aneresdo 193 Jo Ao][Ng Weg LOAdAa VITHL GNV SHONYHAOD 'TIVANTH JO SENGTIWALSOCCVY SNOTUVA ‘ITIL WTA Vib 91 safety block on the knock-off lever of the Corliss valve gear under the tail plate on the grab hook so that the hook plates clears the catch block and the steam valve will not open. By this arrangement the engine is ready to start and the safety device is always ready for action without any attention from the operator. The running speed of the governor is 125 r. p. m. By moving the adjusting weight 1 in or out, the speed of the engine may be increased or decreased several revolutions. Section Through a wricLeyer cert, FIG. 55. ROBB-ARMSTRONG-SWEET TYPE OF SHAFT GOVERNOR in table III are shown some of the results which may be expected in making changes in the adjustment of fly- ball governors. Several types of shaft governors are in use which operate on the same principle but differ in mechanical details. In Fig. 55 is shown a Robb-Armstrong-Sweet type of shaft governor. The eccentric lever for this governor is of the double bearing type with a bearing on either side of the wheel arm to prevent the overhanging weight of the lever from wearing the pins and bushing out of alinement. It is possible to increase the speed of the engine by increasing the tension on the main governor spring, and to decrease the speed by decreasing the tension. If it is found that the governor is too sensitive to variation of 92 loads, this can be corrected by moving the link in the eccentric lever one hole further from the shaft and, if it should be found that the governor is too sluggish in action or not sensitive to variation of load, allowing a variation of speed in the engine, the link in the eccentric lever, may then be moved one hole nearer the eccentric shaft. An important factor in satisfactory operation of the governor is the position of the fulcrum on the main goy- ernor spring. If the governor should be unsteady or have a tendency to hunt or race, this may be corrected by swing- ing the point of the fulcrum further towards the spring weight and again locking it in position. Shaft governors, employ, for their operation, forces of two kinds, first centrifugal force and second inertia. In this respect they differ from flyball governors which em- ploy centrifugal force, only. Most SHAFT GOVERNORS USE INERTIA While it is possible to design shaft governors which use only centrifugal force to control the speed of the engine, it has been found that the governor weight must be made so. heavy that the governor is correspondingly slow or slug- gish in its action. It is for this reason that nearly all shaft governors are so designed that the inertia of the weight will assist the governor in changing position. In governors of this type, advantage is taken of the tendency of a weight to keep on moving at the same speed when the speed of the flywheel changes. If the engine is running at a constant speed, the fly wheel and governor weights will be turning at the same rate. If a load is suddenly thrown on the engine, the flywheel speed slackens but the inertia of the governor weights causes them to move forward at the same rate as before. This movement is utilized by some mechanical means depending on the particular design of the governor. CLASSIFICATION OF SHAFT GOVERNORS The shaft governor may be classified with respect to the arrangement of weights employed, as follows: 1. Bal- anced governors with two weights and their fly wheels in continual balance. 2. Balanced governors with a single weight and their fly wheels not in continual balance. 3. — 93 Governors with a single arm which carries inertia weight, centrifugal weight and eccentric; the governor and its wheel being nearly balanced in all positions. 4. Governors having two arms or an arm and a weight, the governor and its wheel being nearly balanced in all positions. Governors of all of the above classes can be so operated that the regulation can be either assisted or retarded by ATRAVERSE BLOCK tH ——| FIG. 56. HARRISBURG BALANCED TYPE SHAFT GOVERNOR inertia and can be connected to a rotating or a swinging eccentric as desired. In most of the governors used, how- ever, inertia assists the regulation. In Fig. 56 is shown another type of shaft governor, of the centrally balanced centrifugal inertia type. In this type the weight arms are constructed with differential weight pockets to allow a considerable range of speed adjustment without altering the tension of the springs. If an increase of speed is desired, remove weights of equal 94 91qe48 e10UI ‘BAT}ISUIS sso] [NjteMod ssory SATPISUOS SSo'T SATPISUOS SSO'T oules oy} Oq AB |°°*********AOUIOAOS UO YORY eules 94} 9q ABIL ouUlBs 94} oq AB] 19488J IdMOTS JoMOTG |*°** °° *pseds oulzue uo Yogy suds sutids OBBIOAT eseIVAg] Butids ewes ud ° UOISUd} | 19zq3T O3N4IYWSqQns | 443M JO 4YyZIOM Zulids euss joseoloop Jo Zutids pus qFIOM ssveI00Gg | pu’ 4yZIEM osBeIDEG | [eBnyII}U0N OsveIDEq | JO UOIsU9} osBeIDEG | IEzYSTT OFNZIZSGNY |" TTT esuByD 91qeys S8e_ ‘OAT}ISUOS O1OPT [Ny1eMmod s107T SATPISUOS SIOPT OATPISUOS OIOTT ouleS 94} 9q ABT |°° °° °° °° °° *IOUIOAOS UO POOR SUIS 94} 9q ABT OUIBS 94} 0q ABI IBMOTS 19986, 10488 q |***°***pseds ourgue uo yoRW surids sutids OBBIIAIT eBBI9A0] Zulids owes UO TOTSU94 | IOTABOY OfNZIYSQns | 44YsIOM JO 4YZIOM Zu1ids ourvs | osveldur JO Zurids pus 3q3IEM osveroUT | pus 7YFIOM OsBoIOU] | [VBnjtyu90 osveIoUy | JO UoIsUez oBBeIOUL | IOTABOY OMPWSQNG [**""* TTT TTT eBUBYD Bulids pus YSIOM 7qFIOM Sutidg Weg SHONUAAOD LAVHS JO LNHWLISALCV TVdIONIYd ‘AI ATaV 95 thickness from the two weight pockets of the lever and, to obtain a decrease of speed, add weights of equal thick- ness. If an increased number of revolutions causes the governor to race, move the attachment block, in the slot to which the outer end of the spring is attached, farther from the small end of the weight lever. If this does not entirely correct the sensitive condition, the plug is screwed into the spring until the racing ceases. If the decrease of speed so obtained renders the gov- ernor too sluggish in action, move the attachment or traverse block in the slot in the opposite direction. If this does not improve the regulation and the speed is lower than desired, weights of equal thickness are added increas- ing the spring tension until the proper speed is obtained. Table IV shows the effect on shaft governors due to changing the spring tension or making a change in the governor weights. > ve -s - = * ia’ | é > ~~ th sta - aan ~ a * * $ . us ’ ers * ~ ae — ’ fiw, ~ wd is > . ea. - 7 2 et : “ . a a, ~~ » Lae, - ; ' 3 - ke a. es * *. '. eee Fs a! - a = no . : ad BE a WA me a : ? ~s > Ce ie ae &, Re Ris is te ee . " ae “—- ‘ * hes % ‘ ‘ , o ~ EE ns « =f. —- = . ~ Sa ' r . : F \ « i et : : 1 7 ° =k z . . Ni : * ‘ ne . Jt UNIVERSITY OF ILLINOIS-URBANA 2 073256981 3 011