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 1024 of 1313
INSUFFICIENT BRAKES (VEHICLE STOPPING DISTANCE TOO LONG, NO APPARENT AIR SYSTEM
FAILURE WITH GAUGES AT NORMAL OPERATING PRESSURE, WARNING BUZZER NOT SOUNDING) -
Continued
d.
Disconnect delivery lines from tee fitting at limiting valve (Volume 3, WP
0439). Refer to point to point
schematics.
e.
Disconnect tee fitting from limiting valve.
f.
Connect pressure gauge to disconnected limiting valve delivery port.
g.
Assistant starts engine and runs to build air supply to normal operating pressure.
h.
Assistant fully applies and holds service brakes.
i.
Monitor air pressure on pressure gauge.
j.
Measurement can be taken after pressure reaches 90 psi, or after 5 minutes, whichever occurs first.
k.
Pressure gauge should read 90 to 130 psi.
CONDITION/INDICATION
IS LIMITING VALVE DELIVERING PROPER AIR PRESSURE?
DECISION
NO - Go to Step (19).
YES - Replace damaged air lines from limiting valve to front brake chambers (Volume 5, WP
0805). Go to
Step
(30) to verify problem is solved.
TM 9-2320-272-23-1
0120
0120-35
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