Читать книгу The Traveling Engineers' Association to Improve the Locomotive Engine Service of American Railroads - Traveling Engineers' Association - Страница 6

Table of Contents

1. Q. What, in your opinion, is the best way to fire a locomotive?

A. To carry a nice, level fire on the grate, or it may be just a little heavier at the sides and front, so the air cannot come through it near the sheets as rapidly as in the center of the fire-box; always fire as light as consistent with the work required, endeavor to maintain a uniform steam pressure at all times, and avoid unnecessary black smoke and a waste of steam through the safety valves by the engine popping.

2. Q. What are the advantages of superheated steam over saturated steam in locomotive service?

A. Saving in water; saving in fuel; increased boiler capacity and a more powerful locomotive. Superheated steam does away entirely with all condensation in the cylinders, while saturated steam coming in contact with passages in cylinder saddle and walls of cylinders, is immediately cooled and in cooling, a part of it is changed back into water which affects the pressure and therefore its capacity to do work.

3. Q. How is the saving in water produced?

A. By the elimination of all cylinder condensation present in saturated steam locomotives and the increase in volume of a given weight of steam.

4. Q. How is the saving in coal accomplished?

A. Because there is less steam used to do the same amount of work, there is less water evaporated and consequently less coal required to evaporate the water.

5. Q. How is the increased boiler capacity obtained?

A. A boiler will evaporate a certain amount of water into steam and if part of the steam is lost by condensation, only that remaining is available for running the engine. Superheating eliminates the losses, thereby increasing the available useful steam. Further, superheating increases the volume of a given weight of steam, thereby reducing the consumption of steam required to develop a certain power and consequently increases the capacity.

6. Q. How is a more powerful engine obtained?

A. By reason of the increased boiler capacity an engine may be worked farther down before a steam failure occurs.

7. Q. What type of fire tube superheater is in most general use in locomotive service?

A. The top header fire tube type, known as the "Schmidt Superheater." A system of units located in large flues through which the steam passes on its way from the dry pipe to the steam pipes, and a damper mechanism which controls the flow of gases through the large flues.

8. Q. Describe the construction and location of the header.

A. The header is a simple casting, divided by partition walls into saturated and superheated steam passages. It is located between the dry pipe and the steam pipes, the same as the nigger head in a saturated locomotive. The dry pipe is in communication with the saturated steam passages and the steam pipes with the superheated steam passages and these are in communication with each other through the superheated units.

9. Q. Describe the construction of superheater units and their connection to the header.

A. The units are composed of four seamless steel pipes, connected by three return bends. Of the four pipes, two are straight and two are bent upward and connected to the header by means of a clamp and bolt; one end of the unit is in communication with the saturated steam passage and the other with the superheated steam passage in the header casting.

10. Q. Trace the flow of steam through the top header fire tube superheater.

A. When the engine throttle is open, saturated steam passes through the dry pipe into the saturated steam passage of the header casting. From this passage it enters one end of the unit, passing backward toward the fire-box, forward through one of the straight pipes and the front return bend, backward through the other straight pipe to the back return bend, and forward through the bent pipe and upward into the superheater steam passage of the header, from which it enters the steam pipes and is carried to the steam chest.

11. Q. What should be the position of throttle valve when running a superheater locomotive?

A. The engine should always be run with as wide open throttle as the conditions will permit, regulating the steam admission to the cylinders according to work to be performed.

12. Q. What should be the position of throttle while drifting?

A. The throttle valve should be kept slightly open while drifting, so as to admit a small quantity of steam in valve chamber and cylinder above atmospheric pressure, to prevent the inrush of hot air and gases which destroy lubrication, also to prevent excessive wear to valve, cylinder and piston rod packing.

13. Q. How should the water be carried in boiler of superheater locomotives?

A. As low as the conditions will permit, because this practice reduces the tendency to work water over into the dry pipe and units, as the superheater locomotive will use one-third less water than the saturated locomotive.

14. Q. What care should be exercised in lubricating a superheater locomotive?

A. The supply of oil to steam chest should be watched very closely by the engineer, he to know that lubricator is feeding constantly and evenly over entire division, and according to work performed.

15. Q. Describe the general form of a locomotive boiler.

A. A locomotive boiler is cylindrical in form, it usually has a rectangular shaped fire-box at one end and a smoke-box at the other, and flues extend through the cylindrical part, and, like the fire-box, are surrounded by water.

16. Q. How does the wide fire-box type of boiler differ from the ordinary boiler, and what are its advantages?

A. The wide fire-box type of boiler is built so the fire-box is above the frame and extends out over the driving wheels. The advantages of this are to obtain a larger grate area in the same length of fire-box and to give a slower rate of combustion per square foot of grate surface. The deep fire-box is limited in width to the distance between the frames, while the shallow fire-box sets on top of the frames and between the driving wheels.

17. Q. Why have two fire-box doors been placed in the large type of locomotive boilers?

A. For convenience of the fireman on account of the greater width of the fire-box, so that coal can easily be distributed to all parts of the fire-box.

18. Q. Describe a locomotive fire-box.

A. The modern form is a rectangular shaped structure located at the back end of the boiler. It has a door and is composed of two side sheets, a crown sheet, a back sheet and a flue sheet from which the flues extend to the smoke-box at the other end of the boiler.

19. Q. To what strains is a fire-box subjected?

A. To crushing strains and to those of unequal contraction and expansion.

20. Q. How are the sheets of a fire-box supported?

A. They are supported by staybolts screwed through the inside and outside sheets with their ends riveted over.

21. Q. In what manner is a crown sheet supported?

A. By crown bars or radial staybolts.

22. Q. What are the bad features about crown bars?

A. They are hard to keep clean and frequently cause crown sheets to become mud burned.

23. Q. What are the advantages of radial stayed crown sheets?

A. They are easier to keep clean and cheaper to repair.

24. Q. How are the inside and outside sheets of a fire-box secured at the bottom?

A. They are riveted to a wrought iron ring called a mud-ring.

25. Q. Describe the ash-pan and its use.

A. It is a receptacle secured to the fire-box and usually provided with dampers to regulate the flow of air to the fire. It collects the ashes that drop from the fire-box and prevents them from setting fire to bridges or other property along the track. Engine-men must know that ash-pan slide and hopper bottoms are closed before leaving enginehouse.

26. Q. What is a "wagon-top" boiler?

A. It is a boiler that has the fire-box end made larger than the cylindrical part to provide more steam space.

27. Q. Why are boilers provided with steam domes?

A. To furnish more steam space and to obtain dryer steam and to provide a place for the safety valves, steam pipes, throttle valve and whistle.

28. Q. What must be the condition of a boiler to give the best results?

A. It must have good circulation and be clean and free from mud or scale.

29. Q. What is meant by "circulation" in a boiler?

A. Free movement of the water, so that it may come in contact with the heating surface and after being converted into steam be immediately replaced by a fresh supply of water.

30. Q. What would be the effect if a "leg" of the fire-box became filled with mud?

A. There would be no water in contact with the fire-box sheets and they would quickly become overheated and mud-burned.

31. Q. What would be the result if the fire-box sheets became overheated?

A. They would be weakened and forced off the staybolts and an explosion would occur.

32. Q. Would it be advisable to put water into a boiler after the sheets had become bare and red hot?

A. No. The fire should be killed at once.

33. Q. What effect has the stoppage of a large number of flues?

A. The heating surface and draft are decreased by just that much area.

34. Q. Why are boiler checks placed so far away from the fire-box?

A. To introduce the water into the boiler at as great a distance from the fire-box as possible. This permits the water to become heated to a high temperature before it comes in contact with the fire-box and also improves circulation.

35. Q. What part of the boiler has the greatest pressure? Why?

A. The bottom, because it is subject to the weight of the water in addition to the steam pressure in the boiler.

36. Q. What are the advantages of the extension front end?

A. To provide room for suitable draft and spark appliances.

37. Q. What is the purpose of a netting in a smoke-box or front end?

A. To act as a crusher of all cinders and prevent large cinders from passing out of the front end to the atmosphere.

38. Q. What is the object of hollow staybolts?

A. To indicate when the staybolt is broken by the escape of steam through the small hole in the bolt.

39. Q. What will cause the engine to tear holes in the fire?

A. Working hard or slipping when the dampers are open and the door closed, or too thin a fire.

40. Q. Name the various adjustable appliances in the front end by which the draft may be regulated.

A. The exhaust nozzle, the diaphragm and the draft pipes or petticoat pipe.

41. Q. What object is there in having the exhaust steam go through the stack?

A. To create a draft through the tubes and fire-box.

42. Q. How does this affect the fire?

A. The exhaust steam escaping through the stack tends to empty the smoke-box of gases and produces a partial vacuum there, atmospheric pressure then forces air through the grates and tubes to refill the smoke-box, and in this way the draft through the fire is established and maintained.

43. Q. Explain what adjustments can be made and the effect of each adjustment on the fire.

A. Larger or smaller nozzle tips cause less or greater draft on the fire; raising or lowering the draft pipes and diaphragm causes the engine to burn the fire more at the rear or front end of the fire-box; the size and position of the draft pipes increase the draft through the top or bottom flues; the latter adjustments should always be attempted before reducing the nozzle.

44. Q. What does it indicate when the exhaust issues strongest from one side of the stack?

A. The stack, exhaust pipe or petticoat pipe are out of plumb.

45. Q. What is the effect of leaky steam pipe joints inside the smoke-box?

A. The engine will not steam freely.

46. Q. What causes "pull" on the fire-box door?

A. The partial vacuum in the front end; when excessive it indicates dampers closed, fire clinkered or insufficient opening for the admission of air under the fire.

47. Q. If upon opening the fire-box door you discover there what is commonly called a red fire, what might be the cause?

A. The grates may have become clogged with ashes or clinkers so that sufficient air could not pass through them to the fire.

48. Q. Is it not a waste of fuel to open the fire-box door to prevent pops from opening? How can this be prevented more economically?

A. Yes. This can usually be prevented by putting the heater into the tank, or putting on the injector, or by more careful firing.

49. Q. Describe the principle upon which the injector works.

A. The action of the injector is due first to the difference between "kinetic" or moving energy and "static" or standing energy; second, to the fact that steam at a pressure travels at a very high velocity and when placed in contact with a stream of water it is condensed into water, and at the same time it imparts enough velocity to the water to give it sufficient momentum to overcome a pressure even greater than the original pressure of the steam. By imparting this velocity to the water it gives it sufficient energy to throw open the check valves and enter the boiler against high pressure.

50. Q. What is the difference between a lifting and a non-lifting injector?

A. A lifting injector will create sufficient vacuum to raise the water from the level of the tank. The steam tubes in a non-lifting injector are different and it will not raise the water, but merely force it into the boiler. A non-lifting injector must be placed below the level of the water in the tank so the water will flow to it by gravity.

51. Q. Will an injector work with a leak between the injector and tank? Why? Will it prime?

A. A lifting injector will not work if the leak is bad. It will not prime because the air admitted through the leak destroys the vacuum necessary to raise the water to the injector level. A non-lifting injector will work, as the water will escape from the pipe instead of air being drawn into it as with the lifting injector.

52. Q. If it primes well, but breaks when the steam is turned on wide, where would you look for the trouble?

A. Insufficient water supply due to tank valve partly closed, strainer stopped up or tank hose kinked, injector tubes out of line, limed up, or delivery tube cut, or wet steam from the throttle.

53. Q. If it would not prime, where would you expect to find the trouble?

A. Insufficient water supply, priming valve out of order, or with the lifting injector the trouble might be caused by a leak between the injector and tank.

54. Q. Will an injector prime if the boiler check leaks badly or if it is stuck up? If the injector throttle leaks badly?

A. No.

55. Q. If steam or water shows at the overflow pipe when the injector is not working, how can you tell whether it comes from the boiler check or the injector throttle?

A. Close the main steam valve at the boiler, that will stop the leak if it comes from the injector throttle.

56. Q. Will an injector prime if primer valve leaks? Will that prevent its working?

A. It will prime, but not as readily as with priming valve in good condition. This will not prevent its working, but it may waste some water from the overflow.

57. Q. Will an injector work if air cannot get into the tank as fast as the water is taken out?

A. No.

58. Q. If you had to take down a tank hose, how would you stop the water from flowing out of the tank that has the syphon connections instead of the old-style tank valves?

A. Open the pet cock at the top of the syphon before taking the hose down.

59. Q. Is any more water used when the engine foams than when the water is solid?

A. Yes, very much more.

60. Q. How would you prevent injector feed pipes or tank hose from freezing in winter when not in use?

A. The steam valve should be slightly open to permit a slight circulation of steam through the feed and branch pipes. The heater cock should be closed and the drip cock under the boiler check or on the branch pipe should be opened to insure a circulation of steam through the branch pipe.

61. Q. How would you prevent the overflow pipe from freezing with a lifting injector?

A. The overflow valve should be opened just enough to permit a little steam to escape through the overflow pipe to prevent it from freezing.

62. Q. Name the various parts of the injector.

A. The injector consists of a body supplied with a steam valve, a steam nozzle, a primer, a combining tube, a delivery tube, a line check valve, an overflow valve, a water valve, and a lifting injector has a lifting tube.

63. Q. What may be done if a combining tube is obstructed?

A. The steam valve bonnet may be removed and the obstruction forced out with a piece of stiff wire, or uncouple the delivery pipe from the injector and unscrew and remove the tubes; the obstruction can then be removed and the tubes replaced.

64. Q. How is the greatest injury done to a boiler when cleaning or knocking the fire?

A. By excessive use of the blower drawing cold air through the fire-box and flues.

65. Q. Why does putting a large quantity of cold water into a boiler when the throttle is closed cause the flues to leak? When is this most serious?

A. When steam is not being used there is not much circulation of water in the boiler, and the water entering the boiler at about 150 degrees temperature is heavier than the water in the boiler. The cooler water will go to the bottom and reduce the temperature in that part of the boiler and causing the flues to contract in length as well as in diameter and this has a tendency to pull them out of the sheet. This will loosen them and cause them to leak. After the fire has been knocked this tendency is much greater, and for that reason cold water should not be put into a boiler after the fire has been knocked out. Always fill the boiler before the fire is knocked out.

66. Q. Is warm water in the tank of any advantage in making steam rapidly?

A. Yes; careful experiments have shown that a locomotive will generate one per cent. more steam for every eleven degrees that the tank water is heated; thus by heating the feed water in the tank from 39 degrees to 94 would effect a saving of five per cent.

67. Q. Then why not heat the feed water to the boiling point (212 degrees)?

A. If the feed water is heated much above 100 degrees it will not condense enough steam in the injector to cause it to work properly. Some injectors will work hotter water than others. It would also spoil the paint on the tank if heated to a much higher temperature.

68. Q. At 200 pounds pressure per square inch, what is the pressure per square foot on the sheets of a boiler?

A. About fifteen tons.

69. Q. What is the total pressure on the fire-box of a large locomotive?

A. Over 3,000 tons.

70. Q. Give a practical definition of heating surface.

A. The heating surface of a boiler includes all parts of the boiler and tubes that are directly exposed to fire or heat from the fire and are surrounded by water.

71. Q. Should an engine be slipped to get water out of the cylinders or steam passages?

A. No; the water should be worked out by opening the cylinder cocks and starting the engine slowly.

72. Q. What does it indicate when the smoke trails back over the train and into the coaches after shutting off?

A. It indicates poor firing or a lack of understanding between the engineer and fireman in regard to where the engine was to be shut off.

73. Q. Before shaking grates or dumping the ash-pan, what should be observed?

A. That the engine is not passing over bridges or cattle guards, crossings, switches, interlocking fixtures, or in yards. Fire on the track should be extinguished promptly at places where ash-pans are cleaned.

74. Q. Which is easier and more satisfactory on a long run, to stop and clean the fire if necessary or to continue to the end of a long, hard trip with a dirty fire?

A. Stop and clean the fire if necessary. It will save fuel and labor during the remainder of the trip and may also save an engine failure.

75. Q. Should you examine the flues to see if they are stopped up and leaking, and inspect the grate and grate rigging carefully before leaving the engine at a terminal?

A. Yes, so they can be reported if necessary. Clean flues and grates working well make a vast difference in the success of a fireman, and a great many engine failures could be avoided by keeping the flues and grates in proper condition.

76. Q. How should cab lamps, signal lamps, oil cans and lanterns be cared for?

A. They should be kept clean, free from leaks and always filled and ready for service before leaving terminals.

77. Q. About how many drops in a pint of valve oil when fed through a lubricator?

A. About 4,500 drops.

78. Q. Assuming that five drops per minute are fed to each of two valves and one drop per minute to the air pump, how many hours would be required to feed one pint of valve oil?

A. About eight hours.

79. Q. Assuming that the engine is running twenty-miles per hour, how many miles per pint would be run?

A. About 160 miles per pint.

80. Q. How many drops per minute should ordinarily be fed?

A. This will vary with the size of the locomotive and the work to be performed. On small yard engines one drop per minute for each cylinder is usually sufficient and one drop for the air pump every two or three minutes. This depends on the condition of the pump and the service being performed. For large engines in slow freight service four to five drops per minute, and for large engines in heavy fast passenger service from five to seven drops per minute should be fed. Air pumps in freight service where the brake pipe is in moderately good condition can usually be run with one or two drops per minute when handling long trains of cars equipped with air brakes.

81. Q. Will any bad results ensue from filling the lubricator full of cold oil?

A. Yes; when the oil gets hot it will expand and may break the glass or bulge or burst the lubricator.

82. Q. If a sight feed gets stopped up, how could you clean it out?

A. Close the water valve and the regulating valves to the other feeds. Open drain cock and draw out a small quantity of water so as to bring the oil in top part of lubricator below the top end of oil pipe leading to feed arm, then open wide the regulating valve to feed that is stopped up and the pressure from the equalizing tube will force the obstruction out of the feed nozzle and up into the body of the lubricator. Next, close this regulating valve until the feed glass fills with water, then open water valve and start feeds.

83. Q. How would you clean out chokes?

A. First, shut off boiler pressure and condenser valve; next, remove feed valve bonnet, then open main throttle valve, when the steam from steam chest will blow back through the choke plug, clearing it of any obstruction.

84. Q. What is superheated steam?

A. It is the saturated steam separated from the water from which it is generated with more heat added, increasing its temperature from 100 degrees to 250 degrees Fahrenheit above the saturated steam temperature.

85. Q. What is the advantage of superheating or increasing the temperature of the steam?

A. By increasing the temperature of the steam the volume of a given weight of steam is increased and all losses due to cylinder condensation are eliminated, which result in a reduced steam consumption, a saving in coal and water and increased boiler capacity.

86. Q. How is the increased temperature obtained by the use of the superheater?

A. By admitting the saturated steam into a partitioned receiver which has a number of 1½-inch pipes attached to it. These are located in and extend nearly the full length of the large flues, the steam having to pass through these 1½-inch pipes on its way back to the receiver, absorbs the heat from the gases passing through the large tubes, causing its temperature to rise, or in other words, become superheated.

87. Q. How much is the volume of steam increased by superheating?

A. For each 100 degrees of superheat added to saturated steam, at temperatures ordinarily used in locomotive practice, the volume of a given weight is increased roughly from sixteen to seventeen per cent.

88. Q. Why is the superheated steam so much more economical on coal and water than the saturated steam?

A. Because for a given amount of water evaporated you can increase the volume of steam 33 per cent. by superheating. It is readily seen that the coal does not have to be burned if the steam used has 33 per cent. more volume for filling space, or in other words, only so much steam can be admitted to the cylinders for every movement of the valve, and what can not be used must remain in the boiler, so if the engine can not use all of the steam that the boiler is capable of generating, the saving must show in coal and water. If you can not use all of the steam you do not have to burn coal to make it.

89. Q. Which is the better practice, to close the feed valves or water valve while waiting on sidings, etc.?

A. Close the feed valves; the water valve may leak.

90. Q. How can you tell if equalizer tubes become stopped up or broken?

A. If they were stopped up the equalization would be destroyed, and when the steam-chest pressure was less than the boiler pressure the feed would work too fast, the oil would enter the feed glass in a stream instead of forming into drops. If they were broken, the lubricator could not be used. The auxiliary oilers would have to be used to lubricate the cylinders.