Wear safety goggles when performing leakage
tests on valves. Failure to do so may
result in serious eye injury due to high
If air lines are under high pressure when
they are disconnected, they can whip around
and cause injury to personnel. Caution
should be exercised when loosening or
disconnecting air line fittings.
(1) Start engine and build air pressure
to 125 ±4 psi (861 ±28 kPa)
(2) Turn OFF ENGINE switch.
(3) Release PARKING BRAKE.
(4) Fully apply then release service
(5) Disconnect air line 2489 from front
double check valve (top).
(a) If air escapes from air line 2489,
perform Step (6) below and
replace brake treadle valve
(b) If air does not escape from air
line 2489, brake treadle valve
(6) Connect air line 2489 to front double
check valve (top).
BRAKE TREADLE VALVE TEST
(1) Disconnect air line 2684 from
quick release valve.
(2) Connect a 0 to 160 psi (0 to 1103 kPa)
gage to air line 2684.
(3) Observe pressure gage while
assistant applies then releases
service brakes (TM 9-2320-364-10).
(a) If air pressure is not released
from 125 ±4 psi (861 ±28 kPa)
to 0 psi quickly, perform Step (4)
below and replace front double
check valve (top) (Para 12-11).
(b) If air pressure is released
quickly, valve is OK.
(4) Remove gage and connect air
line 2684 to quick release valve.
FRONT DOUBLE CHECK VALVE (TOP)