TM 9-2320-272-24-1
1-24. HYDRAULIC SYSTEM OPERATION (Contd)
(2) The major components for raising and lowering the crane cable and hook for the HOIST action are:
Key Item and Function
1 SHEAVES - Grooved wheels that guide hoist cable through boom.
2 HOIST MOTOR ASSEMBLY - Converts hydraulic power back into mechanical power needed to
turn the hoist drum.
3 UPPER ROLLER ASSEMBLY - Prevents cable from contacting inner boom during winding/
unwinding.
4 CRANE HOIST CABLE DRUM - Is turned by the worm gear in hoist motor assembly. Drum
unwinds cable when turning toward front of vehicle. Drum winds cable when turning toward rear of
vehicle.
5 HOIST CONTROL LEVER - Manual control attached to the control valve that determines
hydraulic oil flow for the raising and lowering action of the crane hoist cable and hook. Lever is
pulled back to raise cable and hook and pushed forward to lower cable and hook.
6 HOIST CONTROL VALVE - Two-way hydraulic valve located under the hoist control lever directs
fluid from the hydraulic pump to the hoist motor assembly and back through the valve to the
hydraulic oil reservoir.
1-76
