vacuum brake valves, or can have them installed, to handle trains in foreign countries where most rail
cars have vacuum brakes.
In addition to the compressor, governor, reservoirs, and valves previously mentioned, all airbrake
systems have many other parts. Typical examples are the cutout cocks; pressure gages; equalizing
reservoir; distributing, feed, reducing, and quick release valves; and deadman control. These are
discussed in the following subparagraphs.
a. Cutout cocks are used to bypass parts of the circuit when they are not needed.
b. Two pressure gages are common in airbrake systems. One indicates main air reservoir and
equalizing reservoir pressures; the other shows locomotive brake cylinder and brake pipe pressures.
c. An equalizing reservoir adds volume to the space above the equalizing piston in the brake
valve so that reductions in brake pipe pressure may be properly made during service applications of the
d. The distributing valve, when actuated by the brake valves, permits air to flow to the
locomotive brake cylinders, maintains pressure against leakage when brakes are held in applied position,
or permits air to exhaust to the atmosphere when brakes are released.
e. A feed valve automatically maintains a predetermined air pressure in the brake pipe.
f. A reducing valve reduces main reservoir pressure for independent airbrake operation or for
an air signal system.
g. A quick release valve provides a rapid release of brake cylinder pressure during the release
h. Deadman control is a safety device which must be pressed when the locomotive is in
operation. It is released only when the brakes are to be applied. Release of the deadman pedal causes a
warning whistle to sound for approximately 4 seconds after which the brakes are automatically applied;
automatic application of the brakes can be avoided if the pedal is pressed again during the warning