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 1064 of 1313
VEHICLE VIBRATES, CHATTERS, OR BOUNCES WHEN BRAKES ARE APPLIED - Continued
T0241DAA
Figure 2.
Rear Service and Spring Brake Chamber.
d.
Disconnect delivery line from service brake chamber adapter fitting (Volume 3, WP
0434). Refer to point
to point schematics.
e.
Connect tee between disconnected service brake chamber and delivery line.
f.
Connect pressure gauge to tee.
g.
Assistant starts engine and runs to build air supply to normal operating pressure.
NOTE
Air pressure to front service brake chambers must compare with reading on secondary
air pressure gauge. Air pressure to rear spring and service brake chambers must
compare with reading on primary air pressure gauge.
h.
Assistant fully applies and holds service brakes while comparing pressure gauge reading to instrument
panel air pressure gauge reading.
i.
Pressure gauge should read 90 to 130 psi.
j.
Both readings should be similar.
CONDITION/INDICATION
DO REAR BRAKE CHAMBERS HAVE PROPER AIR PRESSURE?
DECISION
YES - Go to Step (4) to verify problem is solved.
NO - Perform Insufficient Brakes troubleshooting (WP
0120).
TM 9-2320-272-23-1
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