Q. As the pump runs all the time that the engine is working, but is not always feeding, how can it be told whether or not it is forcing water?

A. By the pet-cock on either the upper air-cylinder or the feed-pipe. The force of the stream which emerges from this when opened, enables the runner to estimate the amount of feed-water passing.

1. Shaft. 2. Shaft-quadrant. 3. Shaft-handle. 4. Shaft-hanger. 5. Shaft-rod. 6. Cock-shaft. 7. Cock-shaft Bearing. 8. Cock-shaft Hanger. 9. Cock. 10. Pipeclamp.

Q. How is the supply of feed-water furnished by the pump regulated?

A. By a feed-cock in the suction-pipe, regulating the amount that can pass to the pump (see Figs. 102 and 103); also by the valves between tank and tender-hose.

Q. What would be the result of over-feeding the boiler? A. The steam-space would be filled and water would get into the steam-pipes and be likely to wreck the cylinders.

Q. What would be the result of under-feeding?

A. The crown-sheet and upper flues would be left uncovered with water and liable to be overheated, or, as it is called, burned.

9. Feed-cock Body.

Fig. 104. Feed-cock.

10. Feed-cock Plug and Nut. 11. Hose-coupling Nut. 12. Hose-swivel. 13. Feed-pipe.

Q. Should the feed-cock plug extend through its case, or not?

A. To prevent leakage it is better that it should not. Q. What is the use of a dip-pipe in the upper air-chamber?

A. To prevent the chamber filling up with water, where the water is taken from the top.

Q. At what part of the boiler should the feed-pump discharge?

A. In the coolest part; say one and one-half or two feet back of the front flue-sheet.

Q. How is the pump prevented from freezing and bursting, in case the engine is lying by without steam on?

A. By a frost-cock or bleeder on the lower air-chamber, to permit the water to be let out. A similar contrivance is usually on the feed-pipe.

Q. now is the water in the pump, suction-pipe and tank prevented from freezing without being bled out?

A. By heater-pipes communicating either with the steam in the boiler or with injectors, and discharging into the suction-pipe.

Q. Is there such a thing as "suction"? A. Indirectly there is. So-called "suction" takes place when the pressure in one direction upon the "sucked" or "drawn" fluid (be this fluid gaseous or liquid) is partly or entirely removed; the unbalanced pressure in the opposite direction then forces the non-relieved fluid toward that portion thereof which has had the pressure thereon lessened.

Q. What do you think about letting the fireman pump the engine?

A. If he has judgment enough about the firing, and as it is his back that gets the work of coal-shoveling, he should be let pump; but the present position of injectors would make it difficult.

Q. What is the best way to pump an engine, to avoid leaky flues?

A. Fill the boiler at the start and pump light, in accordance with the steam demand.

Q. How should an engine be pumped-continuously from beginning to end of trip, or would you shut off the injector when pulling out after each stop?

A. Shut off the injector when the throttle is opened to start, and start it again as soon as lever is hooked up after train is under way, or steam pressure begins to raise again. When pulling out after a stop the steam pressure must be kept up against a large amount being used by the cylinders, the fresh coal put in on a fire that has not been burning fiercely while engine was shut off, and supply of water put in by the injector. As water rises when the throttle is opened, with some engines it is an advantage to ease or shut off the injector for a minute or two at the instant of pulling out, and keep injector at

work after shutting off, while fire is still burning fiercely, and thus save that heat which would make engine blow off. This method will help along a poor steamer; if it does that, it will help a good steamer burn less coal. Q. How can the boiler be filled while the engine is being towed in?

A. By plugging whistle and relief valves, screwing down the plugs over the injector overflow-valves, opening injector steam and water valves, shutting cylinder cocks, putting reverse lever down in the direction in which the engine is being towed, and opening the throttle.

Q. How can one engine be pumped from another?

A. (1) By plugging all openings which would admit air into the boiler, opening throttle and steam and water connections to injectors or feed pump, setting the reverse lever for towing in one direction and getting towed fast enough to oil the valves through hand oilers. A vacuum being formed in the boilers by the air being pumped out, the water will flow in from the tender. (2) By connect

ing a hose from the delivery or overflow pipe of the live engine, and injector suction of the dead one, or even feeding through whistle, safety-valve, or wash-out plug.

Q. How would you fill the boiler and get the engine alive when fire is drawn on account of low water?

A. If another engine was handy, get her to pump my engine up; otherwise take out the safety-valve and fill with pails.

Q. What are the advantages of pumps over injectors? A. The water-supply is exactly proportioned to the steam-consumption as long as the cut-off is kept the

same.

Q. What are the disadvantages?

A. Feeding can not be done when the engine is standing still; the water is fed cold.

CHAPTER XXVII

THE CHECK VALVE

Q. What enables removing the pump for inspection or repair, while steam is on the boiler, or the latter is full of water?

A. There is between it and the boiler a valve which, as it opens only in the direction of flow of the water from the pump to the boiler, permits the water to pass only in

Fig. 105. Pump-check.

1. Check-body. 2. Check-flange. 3. Check-flange Studs. 4. Valve. 5. Valve-seat 6. Valve-cage. 7. Casing. 8. Check-pipe Coupling-nut.

that direction. Fig. 105 shows a pump-check composed of a check-body 1 and flange 2, held together by checkflange studs 3. The valve 4 contained in the valve-cage 6 seats itself on the valve-seat 5; the whole being surrounded by a casing 7 and attached by a check-pipe coupling-nut 8.