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 1025 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
STEP
19.
IS THERE PROPER AIR SUPPLY PRESSURE AT LIMITING VALVE?
a.
Stop engine and open all draincocks until brake system air pressure is vented.
b.
Close all draincocks.
c.
Disconnect pressure gauge from vehicle and return tee fitting and air lines to original condition.
Transducer
T0219DAA
Limiting Valve
Air Supply Line
Figure 18.
Limiting Valve.
d.
Disconnect air supply line from limiting valve (Volume 3, WP
0439). Refer to point to point schematics.
e.
Connect pressure gauge to o disconnected limiting valve air supply line.
f.
Assistant starts engine and runs to build air supply to normal operating pressure.
g.
Assistant fully applies and holds service brakes.
h.
Monitor air pressure on pressure gauge.
i.
Pressure gauge should read 90 to 130 psi.
CONDITION/INDICATION
IS THERE PROPER AIR SUPPLY PRESSURE AT LIMITING VALVE?
DECISION
NO - Go to Step (20).
YES - Replace defective limiting valve (Volume 3, WP
0439). Go to Step (30) to verify problem is solved.
TM 9-2320-272-23-1
0120
0120-36
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