2. THEORY OF WINCH OPERATION
THE LANTEC HYDRAULIC WINCH is made up of these basic assemblies.
1. Primary drive: motor mount, spring applied / hydraulic released brake, primary
planetary reduction
2. Final reduction: 1 or 2 planetary reduction(s)
3. Drum group: winch drum, winch housing, drive shaft.
The hydraulic motor drives the sun gear of the primary planetary reduction. The output
of this reduction is transmitted by the drive shaft which passes through the center of the
winch drum to the sun gear of the final planetary reduction in the final drive gear
housing. The output from the final planetary reduction is transmitted directly to the
winch drum by a spline connecting the final drive planet hub to the winch drum.
The primary drive also contains a wet multi-disc type brake that runs in hydraulic oil.
The brake is connected to the sun gear of the primary planetary reduction by a cam
type overrunning clutch. The brake is held engaged by springs and is released by an
annular hydraulic piston. This brake piston is connected to the motor port which is
pressurized during reverse (pay out) rotation, and becomes the exhaust port during
forward (haul in) rotation. In this way the brake is held engaged at all times until the
winch is powered in reverse (pay out).
The brake hub forms the outer race of the cam type overrunning clutch. The shaft of the
primary sun gear forms the inner race for the overrunning clutch. When the winch is
powered in forward (haul in) rotation, the overrunning clutch permits the sun gear to run
free and the full power from the hydraulic motor is transmitted to the winch drum. When
hydraulic oil is supplied to the motor for reverse (pay out) rotation, the overrunning
clutch will "lock up" and the motor will not rotate until the pressure builds up and
releases the brake sufficiently to permit the primary sun gear and brake plates to rotate
as a solid unit.
The unit can be used to pay out any load (up to the designed maximum load) with
smooth acceleration and deceleration. This is achieved by the special design of the
self-regulating friction brake. When a load is applied to the cable on the winch drum it
causes the overrunning clutch to "lock up" and the load is held entirely by the friction
brake. In order to lower the load, hydraulic pressure is applied to the reversing side of
the motor. The brake piston also sees this pressure, and, when the pressure becomes
high enough, the brake releases sufficiently to allow it to slip. If the load on the winch
drum tried to drive the motor faster than the supply of oil will permit (i.e. if the motor tries
to act as a pump), the hydraulic pressure will decrease in the brake piston causing an
increase in braking effort. In this way a balanced pressure is supplied to the brake
piston according to the load on the winch drum. The speed of the winch in either
direction is purely dependent on the volume of oil supplied to the motor through the
control valve.
LANTEC Product Support - Installation and Maintenance Manual
2
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