TM5-3810-305-10Winch Theory of OperationThe winch is made up of four basic assemblies:winch base, hydraulic motor and brake valve,brake cylinder and motor support, and drumassembly. The hydraulic motor turns the gears inthe drum assembly, working the cable.The winch has a dual braking system: a dynamicbrake and a static brake. These two types ofbrakes work together to control the speed of thedrum assembly. The dynamic brake uses hy-draulic pressure to operate the brake valve whichcontrols the flow of hydraulic oil to the hydraulicmotor, The static brake is made of multiple-friction discs, a brake clutch assembly, and ahydraulic piston and cylinder. The static brake isautomatically applied unless it is released bybrake valve pilot pressure at a level lower thanthat required to open the pilot-operated spoolvalve.Either brake system does not affect the winchduring hoisting operations. When the operator’scontrol is placed in neutral, rollers between thecam and outer race wedge to prevent the drumassembly from turning. The brake valve stops oilflow from the hydraulic motor. For lowering aload slowly, the operator can allow only enoughoil to release the brake without engaging the hy-draulic motor. The heat build-up is dissipated bythe hydraulic oil. For faster lowering, the hy-draulic pressure is increased by the operator toboth release the brake and engage the hydraulicmotor.3-3 (3-4 blank)
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