ts before it
enters the steam pipes leading to steam chest.

11. Q. In placing engine on the turntable, at water or stand pipes, or
at other similar places, what must be done?

A. Close throttle valve sooner so that the steam confined in superheat
units, pipes and steam chests, will have passed out to the atmosphere.

12. Q. After a locomotive has been started, how can it be run most
economically?

A. By regulating the supply of steam to the steam chest with the
throttle and the point of cut-off with the reverse lever; so that no
more steam be used than necessary to maintain the proper speed, whenever
possible working the engine at short cut-off so as to use steam
expansively.

13. Q. What is meant by working steam expansively?

A. Hooking the reverse lever up toward the center gives the valve a
shorter travel and closes the live steam port when the piston has made
only a part of its stroke. This cuts off the supply of live steam coming
from the steam chest. The expansion of the steam already in the cylinder
pushes the piston to the end of its stroke without the use of a full
cylinder of live steam.

14. Q. How rapidly should water be supplied to the boiler?

A. No faster than it is evaporated into steam, unless just before a hard
pull; or when shutting off with a heavy bright fire in the fire-box to
prevent waste of steam at the pops.

15. Q. What is the difference between priming and foaming of a
locomotive boiler?

A. Priming is caused by carrying the water too high in the boiler so
that when the throttle valve is opened some of it passes over with the
steam in the form of a spray. Foaming is caused by the water becoming
dirty from animal or alkaline matter, so that heat makes it foam like
soap suds. Muddy water or certain vegetable matters will also make a
boiler foam.

16. Q. What should you do in a case of foaming? What in a case of
priming?

A. In a case of foaming, if possible, allow the boiler to cool off a
little, increase the supply of feed water to prevent water getting too
low, and whenever possible blow some of the dirty water out of the
boiler, replacing it with clean water. In case of priming, shut off the
supply of feed water until the water level drops to the proper height in
the boiler.

17. Q. What danger is there when the water foams badly? When it primes
badly?

A. There is danger of knocking out cylinder heads, cutting the valves,
stalling on some grade or getting on some train