Modern Machine-Shop Practice Part 241

15. Piston valve rings.

16. Piston valve rings.

17. Upper valve bus.h.i.+ng.

18. Lower valve bus.h.i.+ng.

19. Reversing piston casing.

20. Reversing piston.

21. Piston rings.

22. Reversing cylinder cap.

23. Reversing valve bush.

24. Reversing valve cap.

25. Piston rod nut.

26. Piston packing gland.

27. Piston packing nuts.

28. Packing glands.

29. Right Chamber cap.

30. Left chamber cap.

31. Air valve bus.h.i.+ng.

32. Air valve.

33. Air valve.

34. Air valve.

35. Delivery union.

36. Exhaust steam outlet.

40. Steam cylinder gasket.

42. Top air-pump gasket.

43. Bottom air-pump gasket.

44. Waste water pipe.

46. Exhaust union stud.

49. Air exhaust union stud.

A side view of the driving wheel brakes is shown in Fig. 3347 and an end view in Fig. 3348. The brakes are, it is seen, suspended by links so that their weight tends to keep them from the wheels. The brake piston rod carries at its end two links which attach to the arms attached to the brakes. The ends of these arms being curved roll together, the arrangement forming in effect a rolling toggle joint. The construction of the piston of the driving wheel brake is shown in Fig. 3349. The piston is made air tight by leather packing indicated by 11, held out by a spring 12. The piston rod packing, 7, is leather held in place by the cap 6 and the spring 8. The air for operating the brake enters below the piston.

[Ill.u.s.tration: Fig. 3347.]

[Ill.u.s.tration: Fig. 3348.]

LOCOMOTIVE RUNNING.

The engineer's duty in running a locomotive is more arduous and requires more watchfulness than any other engine running, because of the peculiarities attending it. In the first place, the jolts and jars to which the engine is subject are liable to cause nuts, pins, etc., to come loose, and some of the parts to become disconnected and cause a breakdown of the engine.

This renders necessary a careful examination of the engine, which should be made both before and after each trip.

In the second place, we have that the amount of load the engine has to pull varies with every varying grade in the railroad track, and the variation is so great that on some descending grades the engine may require no steam whatever, while on ascending grades the utmost power attainable from the engine may be required. In firing, feeding the pumps, oiling the parts, and determining the depth of water in the boiler, the grade and the length of each grade has an important bearing, and so has the weather, since it is clear that between the heat of summer and the blizzards of winter there is a wide range of the conditions under which the engine runs.

In former times, from the less perfect construction of locomotives, the engineer's duties were greatly enhanced from breakdowns, which are comparatively rare with modern locomotives, and there is promise that from improved construction and safeguards they will become less frequent in the future.

It is as important for the locomotive engineer to be familiar with the track as it is to be with the engine, and there is no field of engine driving or running in which more scope is permitted to the engineer to exercise judgment and skill in his management, so as to effect economy in fuel consumption.

The quality and size of the coal is another element that requires attention and observation on the part of the engineer, in order that his train may keep its time and the fuel consumption be kept down.

GETTING THE ENGINE READY.

The first thing to be done in getting ready for a trip is to see that there is sufficient water in the boiler, so that if there is not, there is time to supply the deficiency.

If the boiler is cold it may be that the condensation of the steam in cooling may have left a partial vacuum in the boiler, and it will be necessary in that case to open the top gauge c.o.c.k and let in air so that the water will come to its proper level in the gauge gla.s.s. Similarly, in filling the boiler, it may be necessary to open a gauge c.o.c.k to let the air out.

The lower c.o.c.k of the gauge gla.s.s should be opened to let the steam blow through if there is pressure on the boiler, or to let a little water out if there is not.

The safety valve should next be examined and moved to see that it works properly and does not stick to its seat.

Before laying the fire the fire bars and ash pan should be cleared of ashes and clinkers, and the grate bars tried with the shaking levers to see that the grates will shake properly. It should be seen that the tubes, etc., are clear of ashes.

In laying a new fire an ample supply of lighting material should be used, disposing it so that the fire will light evenly and not in spots, and a good layer of wood should be evenly distributed over the bars, the thinnest pieces being at the bottom as they will light easiest, and it is necessary to light the fire at the bottom, so that the heat from the wood that is first lighted shall pa.s.s through that to be lighted.

The wood should be kept burning without coal until the lower stratum has ceased to blaze and covers the bars, while there is an even layer of blazing wood above it.

[Ill.u.s.tration: Fig. 3349.]

The quant.i.ty of coal to be fed at a time, and the depth of fire to be kept, depends upon the size of the coal, because the larger the coal the less it obstructs the draught, and the thicker the layer required in order to prevent currents of air from pa.s.sing through without entering into combination with the gases from the coal.

If the coal is mixed, containing large lumps, they should be broken.

The first layer of coal should be enough to cover the fire to a depth of about two inches, which will permit of a good draught. This will get well alight while the wood is still serviceable, and a second layer may be applied of another two inches. The third feeding should be given with a view to have a greater depth of fire at the sides than at the middle of the fire box, because the cool sides of the box prevent perfect combustion, and currents of cold air are more apt to find their way through the sides than in the middle of the fire box.

Banking a fire consists of piling it up at the back half of the fire box and covering it up with green coal, so that it may keep alight and keep the boiler hot without increasing the steam pressure.

The air pa.s.sing through the uncovered half of the fire bars prevents rapid combustion and a dead fire is maintained.

In starting up a banked fire, the first thing to do is to clean it of ashes, clinker, etc., shaking up the bars to see that they will work properly. The fire is then spread evenly over the bars, and wood fed to enliven the fire and promote the draught.

The blower or blast pipe is then set going, and coal gradually fed a little at a time, evenly distributed, covering those parts the most where the fire burns through the most brightly.

A steady fire is better than one that is forced, because the combustion is more perfect and less clinker is formed, hence less cleaning will be necessary, and the fire door will not be kept open so long to let in cold air. This is important because a steady temperature in the fire box promotes its durability, as well as giving a uniform boiler pressure.

The strains placed upon a fire box by a fierce fire suddenly cooled by a heavy charge of coal or of cold air from an open fire door are highly destructive.

Furthermore, the greatest economy of fuel is attained by keeping the boiler pressure up, and using the steam expansively by hooking up the links to shorten the point of cut-off.

A safety valve steadily blowing off steam, whether the engine is running or not, is a sign of bad firing and wastefulness.

It is the fireman's duty to attend to the fire, but nevertheless a careful engineer will be as much interested in proper firing as in his own duties, and as the engineer has more experience than the fireman, he is warranted in exercising an ordinary supervision on the firing, which will be welcome to an earnest or ambitious fireman.

The engineer should examine, with a wrench in hand, the bolts and nuts about the trucks and axle boxes, as these are apt to become loose and come off on the road. A proper construction would remedy this defect almost entirely, and by a proper construction is meant the more frequent employment of split pins, cotters, and other similar safety appliances now omitted for the sake of economy of manufacture.

Nothing in the future of the locomotive is more certain than improvement in this respect, and nothing is more urgently needed, as any engineer will become satisfied if he will gather up along a mile of ordinary railroad the nuts and washers that lay along the track.

The eccentric straps and the pins in the link motion require an examination, which may be done while oiling the parts of the engine.

The oiling requires careful attention; first the cups themselves sometimes become loose, an argument in favor of having, wherever possible, the cups solid on the parts, as done in European practice.