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 215 of 1313
TRANSFER CASE CONTROL SYSTEM OPERATION - Continued
A. INTERLOCK AIR CYLINDER
- Under air pressure, a piston in the interlock air cylinder forces a shaft
against one of three grooves in transfer case shift lever. This prevents transfer case from being shifted with
transmission in gear.
B. INTERLOCK SOLENOID VALVE
- Releases air from interlock air cylinder when transmission is in
NEUTRAL and transfer case shift lever switch is depressed. This permits the transfer case high/low shift
shaft to move.
C. FRONT-WHEEL DRIVE AIR CYLINDER
- When under pressure, it moves transfer case clutch forward
to engage front-wheel drive.
D. FRONT-WHEEL DRIVE VALVE
- When tripped by a cam on transfer case shift shaft, the front-wheel
drive valve routes air to front-wheel drive air cylinder.
D
A
B
C
G0020DAA
Figure 8.
Transfer Case Control System Components.
TM 9-2320-272-23-1
0003
0003-10
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