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 99 of 481

TM 9-2320-272-10

1-82

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.

TURNTABLE ASSEMBLY

- Driven by the swing motor through a ring gear

at the base of the assembly, permits the crane to swing 360 degrees.

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.

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

1-21. CONTROL SYSTEM OPERATION (Contd)

(4) The major components for swinging the crane left and right for the SWING

action are: