th of time.

200. Q. Why is it dangerous to repeatedly apply and release the brakes
without giving time for the auxiliaries to fully recharge?

A. As time is required to charge the auxiliaries, the feed groove in the
triple valve being small, if the brakes are repeatedly applied and
released without giving time to recharge, the braking power will be
lost.

201. Q. What benefits are derived from the use of the retaining valve?

A. By use of the retaining valve the brake is held applied while the
triple valve is in release position and the auxiliary is being
recharged; thereby assisting in retarding the movement of the train down
grade, also keeps the train bunched and gives a higher brake power on
the second application with the same reduction of brake pipe pressure.

202. Q. With a seventy-pound brake pipe pressure how much of a reduction
is necessary to set the brakes in full, and why?

A. About twenty pounds. This will cause the auxiliary reservoir and
brake cylinder pressures to equalize.

203. Q. What effect has piston travel on the pressure developed in the
brake cylinder?

A. The longer the piston travel the greater the volume or space to be
filled with air; therefore the lower the pressure.

204. Q. When should brakes be tested?

A. Brakes should be tested before leaving a terminal and after any
change in the make-up of the train, at all designated points, also,
whenever the engineer is in doubt as to his having the control of all
brakes.

205. Q. How should a terminal test of the brakes be made?

A. After the pressure is pumped up, a reduction of about ten pounds
should be made and the length and force of the brake pipe exhaust should
be noted, also the manner in which the exhaust closes; then a further
reduction of ten pounds should be made and the brake held applied until
signaled to release.

206. Q. If, when making a service application of the brake, the brake
pipe exhaust closes suddenly and then begins to blow again, what does it
indicate?

A. That the brakes, or at least part of them, have applied in quick
action.

207. Q. What is meant by a running test, and when should this test be
made?

A. A running test is made while the train is in motion, and steam is
being used, when a sufficient reduction should be made to apply all
brakes. After noting the efficiency of the brakes they should be
released. Running tests should be made following all standing tests and
at all other points on t