TM-9-2320-272-10
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; OPERATOR'S MANUAL
SEPTEMBER 2004
CHANGE 2
TM-9-2320-272-10 - Page 95 of 481
TM 9-2320-272-10
1-78
1-21. CONTROL SYSTEM OPERATION (Contd)
d. Medium Wrecker Crane Hydraulic System Operation.
The M936/A1/A2 medium wrecker is equipped with a hydraulically-operated
crane that extends a maximum 18 feet (5 meters), elevates 45 degrees, and swings
360 degrees. It is capable of lifting loads up to 20, 000 lbs (9, 090 kg).
(1) The crane hydraulic system converts power of the engine into fluid power for
use by the hydraulic pump. At this pump, oil pressure is supplied to different crane
control valves: BOOM, HOIST, CROWD, and SWING. Each of these actions are
dealt with separately. The major components for raising and lowering the wrecker
boom are:
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