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DESCRIPTION OF THE MODEL R5
172 REV.950101
GENERAL DESCRIPTION:
The PULLMASTER Model R5 is a planetary, hydraulic winch primarily intended for mobile or recovery adaptations.
The winch has equal speed in both directions and a freespool feature which can be operated manually or
hydraulically, depending on the option. The main components of this unit are:
✛
high torque, low speed hydraulic motor
✛
multi-disc brake with over-running clutch
✛
planetary reduction
✛
brake housing
✛
cable drum
✛
final drive housing
✛
freespool mechanism
FUNCTION IN FORWARD ROTATION (PULLING):
In forward rotation, or when the winch is pressurized for pulling, the output torque and rpm of the hydraulic motor
are transmitted through the brake shaft and freespool coupling to the final sungear. The planet gears are driven by
the final sungear and cause the planet hub to drive the cable drum at a reduction of 9.25:1. When a load is pulled,
an over-running clutch which connects the motor drive shaft to the automatic brake assembly, permits free rotation
of the sungear, without effecting the brake. When the winch rotation is stopped, the load on the cable drum causes
the over-running clutch to lock and the load is held safely by the disc brake.
FUNCTION IN REVERSE ROTATION (PAYING OUT):
In reverse rotation, or paying out of a load, hydraulic pressure from the reverse side of the hydraulic motor is
channelled to the brake piston, causing the brake piston to release the multi-disc brake. The pressure required to
release the brake is 400 - 600 psi (28 - 42 bar). The over-running clutch, connecting the motor drive shaft to the brake
assembly, locks, causing the brake discs to rotate between stationary divider plates. If the load on the cable drum
increases the pay out speed, the resulting pressure drop in the brake piston increases friction between the friction
plates and slows the drum. In this way, a completely smooth pay out speed can be achieved in a stepless operation
by modulation of the winch control valve. When the control valve is returned to neutral position, rotation stops and
the disc brake applies automatically.
During pay out operations of the winch, the friction created by the brake discs results in heat. This heat is dissipated
by the circulation of hydraulic fluid from the brake housing, supplied internally through the hydraulic motor. This
circulation flow is internally vented to the return line through a check valve arrangement inside the specially modified
motor. The circulation flow is supplied only when the wire rope is payed out. A separate vent line connecting the
PULLMASTER Model R5 with the hydraulic reservoir is not required (see TYPICAL HYDRAULIC CIRCUIT).
IMPORTANT:
SAFETY VALVE
The PULLMASTER Model R5 winch does not require a drain line up to 100 psi permissible back
pressure in the brake housing. To indicate excessive pressure and potential damage to the
hydraulic motor or to the oil seal in the brake housing, a safety valve is installed on the motor
adaptor.
BREATHER RELIEF VALVE
Excessive pressure in the brake housing will damage the oil seal separating the brake housing from
the drum interior. Damage to this seal will cause the drum to fill up with hydraulic fluid. To prevent
damage to the drum seal and end cover of the final drive if the cable drum fills up with hydraulic
fluid, a breather relief (PARTS REFERENCE item 130) is installed on the end cover. The breather
relief does not prevent oil seal failure but serves as an indicator or warning that the seals between
brake housing and the cable drum interior have failed and must be replaced immediately.
