e is found a combined strainer
and check valve with a choke fitting and cut-out cock, which when open
forms a connection between the brake pipe and the main reservoir.

117. Q. What is the purpose of this device?

A. To provide a means of charging the main reservoir of an engine whose
compressor is inoperative.

118. Q. What is the object of charging a main reservoir of an engine
with a disabled compressor?

A. As the air used in the locomotive brake cylinders comes from the main
reservoir, for the brakes to be operated on this engine it is necessary
that its main reservoir be charged.

119. Q. With a 70-pound brake pipe pressure, what pressure should be had
in the main reservoir when using this device?

A. About fifty pounds.

120. Q. When the dead engine feature is being used, in what position
should the automatic and independent brake valves be carried?

A. Running position.

121. Q. What should be the position of the brake pipe cut-out cock below
the brake valve?

A. It should be closed.

DISTRIBUTING VALVE

122. Q. What is the duty of the distributing valve?

A. To admit air from the main reservoir to the locomotive brake
cylinders when applying the brake, to automatically maintain the brake
cylinder pressure against leakage, to develop the proper brake cylinder
pressure regardless of piston travel and to exhaust the air from the
brake cylinders when releasing the brake.

123. Q. To what is the distributing valve attached?

A. To the distributing valve reservoir.

124. Q. How many chambers has the distributing valve reservoir?

A. Two; pressure chamber and application chamber.

[Illustration: Fig. 8. Release, Automatic or Independent.
Connections: MR, Main Reservoir Pipe; IV, Distributing
Valve Release Pipe; II, Application Cylinder Pipe; CYLS,
Brake Cylinder Pipe; BP, Brake Pipe.]

125. Q. Name the different pipe connections to the distributing valve
reservoir.

A. Referring to Fig. 8, the connection marked "MR" is the main reservoir
supply pipe; "II", application cylinder pipe; "IV", distributing valve
release pipe; "BP", brake pipe; "CYLS", brake cylinder pipe.

126. Q. To what do these different pipes connect?

A. The main reservoir supply pipe connects the distributing valve with
the main reservoir pipe. The application cylinder pipe connects the
application cylinder of the distributing valve with the independent and
automatic brake valves. The distributing valve release pi