Chapter 5

A. A direct motion valve gear is one in which the valve moves in the same direction as the eccentric rod, that is doing the work, in many cases no rocker arm is used. In case a rocker arm is used, both arms point in the same direction like the letter U. An indirect motion valve gear is one in which the valve moves in an opposite direction to the eccentric rod doing the work. A rocker is used in which the arms point in opposite directions from the shaft connecting them. Owing to the design and construction of the Walschaert valve gear, it is a direct motion gear when the engine is running in one direction with the link block in the bottom of the link, an indirect motion when the engine is running in an opposite direction with the link block in the top of the link; usually direct motion when running forward.

33. Q. How can you detect the difference between a blow in valve or piston packing?

A. A blow from the valve is more constant and has a somewhat different sound, while a blow from cylinder or piston packing will blow stronger at the beginning of the stroke and gradually decrease as the stroke is completed.

34. Q. How would you place engine to locate broken admission steam ring in piston valve?

A. Would place engine on quarter, reverse lever in center so as to cover ports, then open throttle; and the steam will blow out of cylinder cock at the end of cylinder where broken valve ring is located.

35. Q. How would you locate broken exhaust ring in piston valve?

A. Watch the cross-head when engine is working steam. As there will be three normal and one light exhausts, you can determine on which side of the engine the light exhaust takes place.

36. Q. What is meant by lead? What by line and line?

A. Lead is the amount of port opening for live steam to cylinder ahead or back of piston when the piston is on the dead center. If the steam edge of the valve is in line with the edge of the steam port when the piston is on the center, it is said to be line and line.

37. Q. What is meant by steam lap?

A. The distance that the valve overlaps the live steam edges of the steam ports when it is in the center of its travel over the seat. This distance is measured at one end only, although the valve laps equally at both ends.

38. Q. What is meant by exhaust lap? What by exhaust clearance?

A. Exhaust lap is the distance that the exhaust edge of the valve overlaps the exhaust edge of the steam port when the valve is in central position. Exhaust clearance is the opening between the exhaust edge of the valve and the exhaust edge of the steam port with valve in central position. If the valve has neither exhaust lap or clearance it is said to be line and line.

39. Q. What is meant by release? What by compression?

A. Release is the point in the travel of the piston when the port is opened. Compression is the distance the piston travels after exhaust port closes before the live steam port opens. During this travel of the piston the exhaust port is closed so the moving piston compresses the steam left in the cylinder.

40. Q. With an indirect valve motion and outside admission valve, what would be the position of the eccentric relative to the crank pin on that side? What with a direct valve gear? What difference between outside admission valve and inside admission valve as to this position?

A. With an indirect valve motion and an outside admission valve, the go-ahead eccentric follows the crank pin with engine running ahead. Without any lap or lead it would be a quarter of a turn or 90 degrees behind the pin, but as all valves have lap and lead, the eccentric is advanced or placed toward the pin enough to move the valve the amount of the lap and lead. With a direct valve gear and an outside admission valve, the eccentric will be a quarter of a turn or 90 degrees ahead of the crank pin and advanced enough to move the valve the amount of the lap and lead. With an inside admission valve and an indirect valve motion, the eccentric will come the same as for an outside admission valve and direct motion, or more than a quarter of a turn ahead of the pin. With an inside admission valve and direct motion, as piston valves are usually put up, the eccentric will follow the pin less than a quarter of a turn.

41. Q. What effect would be produced upon the lap and lead by changing the length of the eccentric rod?

A. Lap depends on the construction of the valve. A change of the eccentric rod would not effect it, but would widen the port opening at one end of the travel and reduce it at the other. It should be equal at both ends. Lead is controlled by the position of the eccentric on the axle and it must be equal at both ends. Changing the length of the eccentric rod from the proper one does not really affect the lead, because no proper measurement can be made until lead is equal at both ends. Therefore improper length of eccentric rods varies the port opening at the beginning of the stroke of the piston at both ends.

42. Q. Why are eccentric rods made adjustable?

A. In order to change their length to make adjustment of the valve gear not as easily made in other ways.

43. Q. Why is it necessary to keep the cylinders free from water?

A. In order to avoid damaging valves and cylinders, to insure perfect lubrication and obtain the most efficient service from the locomotive.

44. Q. Where is the piston rod packing located? Where cylinder packing?

A. Piston rod packing is usually soft metallic rings located inside of a gland at the back end of cylinder and around the rod. Cylinder packing rings are usually cast iron, placed around the piston head and bearing against the walls of the cylinder.

45. Q. How are metallic packing rings on piston rods and valve stems held in place? What provisions are made for the uneven movements of the rod?

A. The packing rings fit into a vibrating cup or cone located inside the gland, being held therein by means of a spring as well as by the steam pressure. Provision is made for uneven movement of the rod by making the inside of the gland larger than the vibrating cup and using a ball-joint ring between the vibrating cup and gland.

46. Q. While running under steam and there is a failure of part of the locomotive which does not seem to prevent running at full speed, how would you proceed?

A. Keep the locomotive running if in your judgment it is safe. Try to ascertain what the injury is and be prepared at the next stop to do such work as the case demands, being careful to make the stop at such a place that the work can be done without interfering with the movements of main line trains.

47. Q. If one side of a locomotive is disabled, what would you do in a general way to make it possible to use steam on the other side?

A. Disconnect enough parts to allow for the turning of the wheels and for reversing of the opposite side without moving the valve on the disabled side.

48. Q. In case a locomotive in your care became disabled on the road, what would you do?

A. First see that the train is protected. Next examine the locomotive and see what is necessary to do to move it and if possible the train. If unable to make repairs at once to bring the engine and train forward, would advise exact condition of engine and ask for help. In the meantime endeavor to move the train so as to give other trains the use of the main line.

49. Q. Suppose a wash-out plug blew out or a blow-off cock broke off or would not close, what should be done?

A. Kill the fire, get the train on a side track, if possible, and if unable to make repairs get the engine in condition to be towed in. In all cases with a disabled engine allow the train to drift to a siding, when possible, and stop between the switches so as to allow other trains to pass through siding.

50. Q. Can a locomotive boiler without steam pressure be filled by being towed by another engine? If towed, how filled?

A. Yes. Close all openings where air could enter the boiler. All relief valves, cylinder cocks, gauge cocks, the whistle valve and air pump steam valve should be closed. Place the reverse lever in full gear in the direction the engine is to be towed with water supply valve and injector throttle open. Use engine oil through auxiliary oil cups to oil valves and pistons. The movement of the pistons in the cylinders will pump the air out of the boiler and atmospheric pressure on water in the tank will force water into boiler when the engine is towed.

51. Q. What should be done if grates should be burned out or broken while on the road?

A. Pull the fire off the broken or burned grates, cover that section with any pieces of iron at hand (fish-plates or angle-bars are very good), then level up the fire, clean ash-pan and proceed with full train.

52. Q. What precaution should be taken to prevent locomotive throwing fire?

A. The netting and smoke-arch should be kept in good condition; cinder slide and hand hole plates securely fastened, ash-pan clean and slide dampers for dumping ashes closed. Care should be exercised in working the engine, especially in the vicinity of stations or places where fire is liable to catch. Avoid working the engine hard so as to prevent throwing cinders.

53. Q. What shall be done with a badly leaking or bursted flue?

A. Plug it if possible with an iron or wooden plug. If in the fire-box end, a piece of scantling or post can be sharpened and driven into the flue from the fire-box door; it will then burn off up to where the water from the bursted flue keeps it wet. If a bottom flue, would cover it with ashes or green coal so that the leakage would not put out the balance of the fire. If able to maintain steam pressure, would then proceed with a full train.

54. Q. What should be done in case the throttle valve stem became disconnected while the valve is closed? If it became disconnected leaving valve open?

A. Would notify the train crew and Dispatcher and arrange to be towed in. With lubricator working, unless in very cold weather so there is danger of the water freezing in the cylinders or steam chest passages, would not disconnect. By taking out lubricator chokes and steam chest valves from the oil pipe, a larger supply of steam could be got into the cylinders. If in to clear of other trains and practicable, would take up the dome cap and connect the throttle again. If disconnected and valve stuck open, would notify the train crew and Dispatcher, reduce steam pressure until the engine could be handled with reverse lever and brake, and proceed with such a train as the engine can handle.

55. Q. In case a valve yoke or stem became broken inside of steam chest, how can the breakage be located?

A. In this case the disabled valve is always pushed to the front end of the steam chest so that with a slide valve or outside admission piston valve the back port is open to live steam. When given steam, the engine will stop on the eighth, and when reversed will move over to the other eighth, being stopped there by the live steam in the back end of the cylinder having the disabled valve. Steam will blow from the back cylinder cock on the disabled side and cannot be changed by reversing the engine. If the valve is pushed far enough ahead to open the exhaust port, steam will blow through the exhaust so the engine cannot be moved. With an inside admission valve the forward steam port will be opened and steam will come out of the forward cylinder cock on the disabled side.

56. Q. After locating a breakage of this kind, how would you proceed to put the engine in safe running order?

A. Would move the valve to central position so as to cover both steam ports, if possible. This may be done by taking out the relief valve if on front side of the steam chest and pushing valve back, or taking up the cover for a slide valve; or taking off front head for a piston valve. Disconnect the valve rod from rocker arm and block valve stem so it cannot blow out of the gland or let valve work back. Loosen cylinder head in order to provide for lubricating cylinder so as to leave the main rod up on the disabled side and proceed on one side. If unable to cover the open steam port it would be necessary to disconnect the main rod on the disabled side, blocking the piston at the proper end of the guides so live steam coming into the cylinder would not move it.

57. Q. If a slide valve is broken, what can be done to run the engine on one side?

A. Remove the steam chest cover, place a thin board between the valve and the steam passages in the seat, replace steam chest cover, disconnect valve rod, and if able to lubricate the cylinders leave up the main rod and proceed on one side.

58. Q. If one of the bolts connecting the two parts of a built-up link on Stephenson gear breaks or is lost, how would you proceed?

A. If temporary bolt cannot be supplied, take down the forward part of the link, disconnect and remove link block, fasten valve to cover ports, and proceed. If moving link will clear rocker arm or other parts of the machinery after link block is taken out, it will not be necessary to disconnect eccentrics.

59. Q. What should be done in case of link saddle pin breaking?

A. Remove the broken parts and block the disabled link in such a position that the entire train could be started, using a very short block above the link block in the link slot and a longer one below it.

60. Q. With one link blocked up, what should be guarded against?

A. Reversing the engine or moving the tumbling shaft arm down so the link on the disabled side can strike it.

61. Q. How can it be known if an eccentric has slipped on the axle?

A. By the uneven exhaust of the engine and a thorough inspection to determine the cause.

62. Q. Having determined which eccentric has slipped, how should it be reset?

A. Place the engine on the center on disabled side and if a back-up eccentric has slipped, would place the reverse lever in full forward gear and mark the valve stem flush with the gland; then place the reverse lever in full back gear and move the slipped eccentric until the mark on the stem returns to its original position, taking notice that the throw of the eccentric is on the other side of the axle from the go-ahead eccentric used as a marker, and tighten up set-screws. To set a go-ahead eccentric, use the back-up one on that side for the marker. If the eccentric had been keyed on, would move the cam until the key-way in the axle came in line with the slot in the cam. Knowing the position of the eccentric in relation to the crank pin, an inspection would show where it belongs. The eccentrics are usually opposite the third spoke in the driving wheel from the pin, sometimes ahead of the pin, in other cases back of the pin, depending on whether it is an inside or outside admission valve, a go-ahead or back-up eccentric.

63. Q. What should be done in case of a broken eccentric strap or rod?

A. For a go-ahead strap or rod take down all broken parts, disconnect valve rod, cover ports, and come in on one side. It is safer to take down also the back-up strap and rod on that side. If the back-up strap and rod is broken, it is possible to secure the bottom end of the link so it will not turn over, work the engine full stroke ahead, proceeding with full train until the main line is clear.

64. Q. How should the engine be disconnected if the lower rocker arm became broken? If link block pin?

A. Would remove broken parts; if moving link would strike anything connected with the rocker box or broken arm it would be necessary to take down both eccentric straps and rods. Block valve central over ports and come ahead on one side. If a link block pin was broken, it might be possible to put a bolt in there to do the work, otherwise block the valve on the center of its seat and if the link will not clear the lower end of the rocker arm take down the eccentric straps and rod. In any case where necessary to take off the eccentric rod always take off the strap also.

65. Q. For what breakdown is it necessary to take down the main rod? The side rod?

A. A broken main crank pin, broken main rod or strap, broken piston rod when near the middle of the rod, broken cross-head or guide, broken valve or seat when steam cannot be kept out of the cylinder. Side rods must come down for broken side rod, broken main pin, or broken side rod pin affecting that rod.

66. Q. If it is not necessary to take down the main rod of disabled side of the engine, how would you arrange to lubricate the cylinders?

A. If cylinder and piston are in good shape and it is possible to block the valve to admit a small quantity of steam into the back end of the cylinder, oil from the lubricator will go through this opening and oil the piston rod and cylinder packing. If not possible to block the valve properly, cover the ports and oil the cylinder through the indicator plug openings or relief plug holes. If not possible to do this, slack off the bolts on the front cylinder head, wedge the head open so oil can be introduced. In some cases it may be necessary to take the head off; that however, allows dust and grit to enter the cylinder.

67. Q. What is the by-pass valve, and what is its duty?

A. By-pass valves are connected to the steam port leading to the cylinder. Its duty is to open when the engine is drifting with steam shut off, and close when working steam, to allow air to pass back and forth from opposite sides of the moving piston.

68. Q. What is a vacuum relief valve? What a cylinder relief valve?

A. A vacuum relief valve is usually located on the steam chest or the live steam passage to the chest and opens when steam is shut off and engine drifting, allowing atmospheric pressure to pass into the steam chest, closing when working steam. A cylinder relief valve is a pop valve screwed into the cylinder head and set at high enough pressure so it does not open in ordinary service, but will open to allow water to pass out when the exhaust port is closed by valves; or on compound engines when the pressure in the low-pressure cylinder gets too high.

69. Q. What would be considered a bad engine or tender truck wheel?

A. One loose on axle; having bad flat spots; very sharp flanges; bad sand spots; cracks shelled out; or other defect that would make the wheel unsafe.

70. Q. What should be done if a tender truck wheel or axle should break?

A. Would place a piece of timber or rail across the tender, jack up the corner of the truck that is disabled chain it to the timber and fasten the timber at the other end to hold it so it would carry the disabled truck. If it is possible to slide the wheel or truck, place a tie across the rail and keep the wheel from turning, then slide it to a siding.

71. Q. What should be done if an engine truck wheel or axle should break?

A. Would block between the engine frame and truck frame over the good wheel on disabled side, swing the disabled corner of the truck to the engine frame with a chain. Look out when crossing frogs that disabled truck does not leave the track. With a broken flange, would block the wheel to prevent its turning and skid it to a siding.

72. Q. What should be done for a broken tender truck spring?

A. Jack the tender up to where it belongs and put a block in place of the broken spring.

73. Q. What should be done with a broken engine truck spring or equalizer?

A. For a broken spring, raise the front end of the engine and place blocks across the equalizers under the truck spring near the spring band. For a broken equalizer, block on top of engine truck boxes and under truck frame.

74. Q. What should be done if a driving spring hanger or equalizer should break?

A. Would block between the driving box affected and under the frame over it, using hardwood block or piece of iron. Would also block the equalizer up to its proper position between the disabled end and the frame, or over the other end, as the type of spring rigging requires, to hold the equalizer level. For a broken equalizer, would block on top of all boxes affected, would raise the engine by running the proper driving wheels upon an incline or wedge to lift the engine while other boxes were blocked; a re-railing frog comes handy for this work.

75. Q. How can an engine be moved if the reverse lever or reach rod were caught at short cut-off by a broken spring or hanger?

A. By removing the pin at the forward end of reach rod, to free the tumbling shaft and allow it to be moved either forward or back to move the engine. A block should be placed over the link block to avoid damaging it when uncoupled, as well as to hold link in proper position to move the engine. This would allow the engine to be moved and clear the main line.

76. Q. How can the blowing of steam past cylinder packing, a valve or valve strip be distinguished or located?

A. Test for a leaky slide valve, place the engine on the quarter on the suspected side with the reverse lever in center notch; the valve should be in the middle of its travel and cover both ports. If steam blows through the open cylinder cocks on that side, the valve or seat are defective. A leaky balanced valve strip will allow steam to blow through the hole on top of the valve into the exhaust port in the seat and very little steam will come out of the cylinder cock; in some cases with the valve barely opening a steam port to the exhaust, air will draw in at the cylinder cock. If there is a drip cock in the exhaust pipe under the saddle, the steam will blow out there. After testing for leaky valve, place the engine on about the forward bottom or top back eighth, block the wheels or set the brakes solid, put reverse lever in corner, open cylinder cocks and give the engine steam. If steam comes out of both cylinder cocks, and testing valve shows it is tight, then the packing is blowing. Cylinder packing should be tested with steam first on one side of the piston and then on the other.

77. Q. If engine should blow badly and be unable to start the train when on the right dead center, on which side would be the blow generally?

A. On the left side. If the side standing on the quarter cannot start the train, the trouble is usually there.

78. Q. If throttle were closed and steam came out of cylinder cocks, what might be the cause?

A. To test for this, first shut off steam connection to the lubricator; steam leaking into the cylinders can come from a leaky throttle or leaky dry pipe.

79. Q. Is it possible to distinguish between a leaky throttle and a leaky dry pipe?

A. Yes; a leaky throttle usually leaks steam at all times. A leaky dry pipe will leak both steam and water. It will show a stream of water at the cylinder cocks when the water level in the boiler is raised above the leak in the dry pipe.

80. Q. What effect have leaky steam pipes in the smoke-arch, and how should they be tested?

A. Leaky steam pipes waste steam and very seriously affect the draft in the front end. A bad leak in the back part of the joint at the bottom will blow into the tubes and make the engine smoke at the door with throttle wide open while standing still. To test them, open the front door and cover the joint with fine cinders. When the engine is given steam, the cinders will blow away from the leak; to properly test them in the shop, water under heavy pressure should be used.

81. Q. How should the test for a leaky exhaust pipe joint, or a leaky nozzle joint be made?

A. About the only test that can be made on the road is to open the front end and reverse the engine with throttle partly opened, watching the suspected joint at the same time. For the bottom one with cinders around the joint, for the top one it can sometimes be detected by holding a torch near the joint.

82. Q. What should be done if a steam chest cracks?