43. Q. What would be the result of starting a heavy train or allowing drivers to slip with the fire too thin on the grates?

A. The fire would be pulled off the grates and into the tubes, leaving the fire bed full of holes and some of the fire remaining on the grates turned over. Large quant.i.ties of cold air would be drawn in, resulting in a rapid decrease of temperature and pressure. The tubes would possibly start leaking and the fire would be in such condition that it could not be built up properly in a long distance. Possibly the grates would become clogged up with green coal--an excellent opportunity for forming clinkers. In this condition, the engine would fail to make steam for the entire trip.

44. Q. Where should the coal, as a rule, be placed in the fire-box?

A. As a rule, more coal is burned along the sides and in the corners than in the middle of the grates; the fire should consequently be kept somewhat heavier along the sides and corners than in the middle.

45. Q. How is the fire affected by and what causes clinkers?

A. A clinker shuts off area of grate surface according to its size, and thereby shutting off that much of the air supply and interfering with proper combustion. Clinkers are caused by firing too heavy in spots, which prevents sufficient air pa.s.sing up through these spots and allows the coal to run together, melting the ash, and sand; running a hoe or slash bar through the fire will bring the points of melted sand together, thereby causing a clinker.

46. Q. How can you best avoid their formation and dispose of them?

A. Light firing and occasionally moving the grates lightly is the best preventive. When once formed, they should be removed if possible by firing around and burning them out.

47. Q. How can you explain the slower burning of the c.o.ke and how understand the proper manner of supplying fresh coal?

A. The gases of coal are lighter than air and will pa.s.s away whether consumed or not. The slow burning of the c.o.ke is due to the fact that it burns from the outside only. When a fire reaches a white or incandescent heat it indicates that the gases are burned and a fresh supply of coal should be added; this is to be done as light as the service performed by the engine will permit.

48. Q. When and for what purpose is the use of a rake on the fire bed allowable?

A. The rake should be used on the fire very seldom, because raking the fire bed tends to form clinkers, especially when the rake is plunged down through the fire to the grate. It may be used when necessary to rake the fire lightly when on the road for the purpose of breaking the crust, which may be found as a consequence of too heavy firing.

49. Q. Within what limits may steam pressure be allowed to vary, and why?

A. Pressure should not be allowed to vary more than five pounds from the maximum for the reason that too much expansion and contraction will take place, which many times is the cause of flues leaking, cracked or broken side sheets and stay bolts.

50. Q. Has improper firing any tendency to cause the tubes to leak? How?

A. Yes; if the pressure is not regularly maintained, the fluctuations of temperature cause constant contraction and expansion to take place. If the fire is not carried level, but is carried heavy in some parts of the fire-box and light in others, holes will be worked in, cold air drawn through, lowering the temperature, chilling the tubes and causing leaks.

Carrying the fire too heavy in some places, causes clinkers to form. If the door is open too long, too much cold air is drawn over the fire, causing the tubes to leak.

51. Q. What do you consider abuse of a boiler?

A. Careless or improperly supplying water to the boiler, improper firing or allowing steam to vary from high to low pressure, causing unnecessary expansion and contraction.

52. Q. Does the stopping up of flues affect the steaming capacity of the engine?

A. Yes; obstructed flues reduce the heating surface, reduce the steaming capacity of the engine, and, as a rule, result in causing the flues to leak. They also cause an increase of speed of the gases through the remaining flues and a poor steaming engine.

53. Q. What causes honeycomb over the flues?

A. Honeycomb on flues is usually caused by the draft through the fire picking up the sulphur and molten clay which is in a molten and sticky condition in the fire; as it pa.s.ses on its way to the stack, some of it strikes the flue-sheet and sticks or pa.s.ses through the flues, clogging up the netting in the front end.

54. Q. How would you take care of a boiler with leaky tubes or fire-box, and why?

A. Keep a bright, clean fire, especially up next to the flue-sheet, and as even a pressure of steam as possible and not use the blower any stronger than is absolutely necessary.

55. Q. Why is it very important that coal should be broken so that it will not be larger than an ordinary sized apple before being put into the fire-box?

A. In order to get rapid and complete combustion, coal should be broken into small pieces; this aids combustion by exposing a larger surface to the flame and can be fired more economically and better results are obtained.

56. Q. Should rapid firing be practiced?

A. No; it should not be practiced for the same reason that heavy firing is wrong. A few moments should intervene between each shovelful to allow the fresh coal to get to burning and to maintain the high temperature in the fire-box.

57. Q. When and why should you wet the coal on the tender?

A. Coal should be wet for the purpose of cleanliness to keep dust from flying and because moderately wet coal gives out more heat for the reason that there is not so much fine coal drawn through the tubes. It should be wet as often as necessary to accomplish these purposes.

58. Q. What are the advantages of a large grate surface?

A. Greater heating surface, lighter fire and more complete combustion are possible with the larger grate surface, because a larger amount is burning at one time at a slower rate of combustion.

59. Q. Why are grates made to shake, and how, when and where should they be shaken?

A. For the purpose of breaking any clinkers that might form and to shake out all refuse from the grates. The best time to shake grates is when throttle is closed, as there is no exhaust to carry the unconsumed gases and sulphur through the flues into the front end, which is liable to choke or clog up netting and cause a steam failure. Grates should not be shaken while pa.s.sing over bridges, near lumber or hay yards or through prohibited territory.

60. Q. Do you understand that coal furnished represents money invested, and should be fired economically and not allowed to fall out of the gangway?

A. The fuel of locomotives is property and represents money invested the same as do buildings, rolling stock, etc.; careless or inefficient firemen who waste fuel destroy property as certainly as though cars or engines were smashed up. The coal should be carefully raked off the deck and in from the gangways; it should not be allowed to fall, as it is wasted and dangerous to people near the track. The deck should be kept clean for greater comfort and convenience.

61. Q. Is is objectionable to fill the tanks too full of coal or overflow tank at standpipes or water tanks?

A. It is. Tanks filled too full of coal are dangerous and a great waste of coal, as the jar when running will cause a part of it to fall off; water overflowing from tanks results in washing away the ballast and in cold weather freezes over the tracks.

62. Q. What are the duties of a fireman on arrival at the terminal?

A. Different roads have different a.s.signed duties for the firemen to perform. They should leave the cab, boiler head, oil cans and deck in a clean condition, boiler full of water, enough fire and steam, so that the hostler will not be required to put in fuel while the engine is in his charge; should know that throttle valve is securely closed, reverse lever in center of quadrant, cylinder c.o.c.ks open, and if equipped with independent brake, it to be applied; in fact, it is an excellent opportunity for a mechanical officer to judge the ability of the fireman and future engineer.

63. Q. Is the engineer responsible for the fireman's conduct while on duty and for the manner in which the fireman's duties are performed?

A. He is. The fireman is under the direction of the engineer, and the fireman's duties are to be performed in accordance with the engineer's instructions.

64. Q. What is the duty of the superheater damper, and how does it operate?

A. The duty of the damper is to control the flow of gases through the large flues, thereby protecting the units which are contained therein from being overheated after throttle is closed. The position of damper when the engine is not working steam, is closed.

65. Q. What will be the effect on the steaming of the engine if the damper does not open properly?

A. Engine will steam poorly for the reason that there will be no draft through the large flues. The steam will not be superheated because heated gases cannot come in contact with superheated units contained in the large flues.

66. Q. How may steam failure be avoided in case the damper fails to operate?

A. The counterweight may be tied up, thereby opening the damper.