TM-9-2320-272-23-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 1 OF 5
SEPTEMBER 2012
TM-9-2320-272-23-1 - Page 1142 of 1313
SPRING BRAKES DO NOT SET (GAUGES AT NORMAL OPERATING PRESSURES, AIR EXHAUSTING NOT
HEARD WHEN PARKING BRAKE APPLIED) - Continued
STEP
4.
DOES AIR VENT THROUGH THE PARKING BRAKE VALVE VENT PORT?
a.
Disconnect vent line from parking brake valve vent port. Refer to point to point schematics.
T0312DAA
PARKING BRAKE
VALVE
VENT PORT
Figure 4.
Parking Brake Valve.
b.
Assistant starts engine and runs to build air supply to normal operating pressure.
c.
Apply spring brake.
d.
Feel for air venting through parking brake valve vent port.
CONDITION/INDICATION
DOES AIR VENT THROUGH THE PARKING BRAKE VALVE VENT PORT?
DECISION
NO - Replace quick release valve (Volume 3, WP
0477). Go to Step (5) to verify problem is solved.
YES - Replace parking brake valve (Volume 3, WP
0431). Go to Step (5) to verify problem is solved.
TM 9-2320-272-23-1
0136
0136-5
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