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 1136 of 1313
SPRING BRAKES DO NOT RELEASE (VEHICLE BRAKES GRAB OR DRAG) - Continued
STEP
6.
IS AIR PRESSURE AT PARKING BRAKE DELIVERY LINE?
a.
Verify engine is running.
T0302DAA
PARKING BRAKE
VALVE
DELIVERY
LINE
Figure 6.
Parking Brake Valve.
WARNING
Loosen supply line at valve very slowly. Stop procedure and tighten fitting of supply line
the moment air begins to escape. Failure to comply may result in injury or death to
personnel.
b.
Release parking brake.
c.
Slowly loosen valve supply line until any air escapes, then immediately tighten the line. Refer to point to
point schematics.
CONDITION/INDICATION
IS AIR PRESSURE AT PARKING BRAKE DELIVERY LINE?
DECISION
NO - Replace parking brake valve (Volume 3, WP
0431). Go to Step (8) to verify problem is solved.
YES - Notify supervisor that brake diaphragms are defective. Action is not possible at this level of maintenance.
TM 9-2320-272-23-1
0135
0135-7
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