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 265 of 1313
MEDIUM WRECKER CRANE HYDRAULIC SYSTEM OPERATION - Continued
A. SWING MOTOR
- Converts hydraulic power back into mechanical power needed to turn the crane turntable when
hydraulic fluid is forced through its worm gear. This gear turns a large gear at the base of the turntable to swing
the
crane.
B. TURNTABLE ASSEMBLY
- Driven by the swing motor through a ring gear at the base of the assembly, permits
the crane to swing 360 degrees.
C. SWING CONTROL LEVER
- Manual control attached to the control valve that determines hydraulic oil flow for
swinging wrecker boom to the left and to the right. Lever is pushed inward for left boom movement, and pulled
outward for right boom movement.
D. SWING CONTROL VALVE
- Two-way hydraulic valve located directly below swing control lever. Valve directs
hydraulic oil from the hydraulic pump to the swing motor assembly and back through the valve to the hydraulic oil
reservoir.
D
C
B
A
G0052DAA
Figure 40.
Swing Action Components.
END OF WORK PACKAGE
TM 9-2320-272-23-1
0003
0003-60
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