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General
Introduction
How the Winch Operates
A winch is normally installed on a skidder or tractor to:
• increase the pulling power of the skidder or tractor.
• reach into an area where a skidder or tractor cannot
go.
• make lift functions available when special attachments
are installed.
The winch has hydraulic clutches that are similar to a
hydraulic (powershift) transmission. Most tractors and
skidders have a PTO (Power Take-Off) that is used to
connect the power from the engine to the winch. The
SCH (Self Contained Hydraulics) on the winch label
indicates that the hydraulic system for control of the winch
is inside of the winch case. When the PTO is operating,
a hydraulic pump in the winch case takes hydraulic oil
from the winch sump and sends it to the hydraulic control
valve. The hydraulic control valve controls the operation
of the winch. Removable covers on the winch case allow
access for repairs and adjustments. The design of the
winch cases permits a variation in the arrangement of
PTO assemblies to fi t the different tractors and skidders
that use these winches.
The PTO is connected to the pinion assembly in the winch.
When the pinion rotates, a spur gear turns the hydraulic
pump and the pinion turns the ring gear (bevel gear). The
bevel gear is connected to an oil clutch for the LINE-IN
(power forward) operation and another oil clutch for the
LINE-OUT (power reverse) direction.
The power through the winch to the wire rope drum is
controlled by a LINE-IN and a LINE-OUT clutch. When
the LINE-IN clutch is applied, the drum rotates to pull the
wire rope into the winch. When the LINE-OUT clutch is
applied, the drum rotates to unwind the wire rope from the
winch at the speed controlled by the PTO rpm.
General
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