TM 9-2320-272-10
1-20.
COMPRESSED AIR AND BRAKE SYSTEM OPERATION (Contd)
A
AIR DRYER - Installed in supply line to wet tank and removes moisture from inlet air to wet tank (M939/A1 air
dryer kit installed only).
B
AIR COMPRESSOR - Draws in air from the intake manifold and forces it into the brake system and wet tank
reservoir.
C
SAFETY VALVE - Located at the inlet side of the wet reservoir, it prevents pressure build-up by releasing air
pressure exceeding 150 psi (1034 kPa) when the governor fails to regulate air supplied by the compressor.
D
WET TANK RESERVOIR - Performs two functions:
•
Traps water in air reservoir to protect other air systems from freezing or corroding.
•
Stores reserve air supply enabling operator to make normal stops when engine stalls or compressor fails.
E
PRESSURE PROTECTION VALVE - Performs two functions:
•
Allows air pressure to build to 60-65 psi (414-448 kPa) before supplying air to auxiliary air-powered
equipment.
•
Closes off auxiliary air system from other systems if an accessory fails and prevents loss of air from
secondary reservoir.
F
ALCOHOL EVAPORATOR (M939/A1 series) - Helps protect air lines from freezing.
G
WET TANK RESERVOIR DRAINVALVE - Provides a drain for moisture and air from reservoir.
H
AIR DRYER - Removes moisture from inlet air to wet tank (M939A2 only).
I
EXPELLO VALVE - Augments air dryer condensation blowdown by venting moisture when compressor cycles.
J
GOVERNOR - Trips valve inside compressor to regulate flow of air to the system. When pressure builds to 120-
127 psi (827-876 kPa), the governor will close valve.
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