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.