WINCH THEORY OF OPERATION

TM 5-2410-237-23

WINCH THEORY OF OPERATION

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WINCH MECHANICAL DESCRIPTION

The winch is bolted directly to the tractor main frame. The splined winch input shaft plugs directly into tractor power

take-off (PTO) shaft.

All winch functions are hydraulically actuated by means of a hydraulic control unit located inside the winch case. The

control unit is connected to the operator's winch hand control lever by means of linkage. System hydraulic flow is pro-

vided by an engine-mounted gear pump.

The winch case is fabricated steel with an integral drawbar. Access covers allow service to components without remov-

ing the winch from the tractor.

The tractor's transmission center shaft is the power source for the winch. It is essentially an extension of the tractor's

main drive shaft driven by the output portion of the transfer case. The end of center shaft is splined and acts as the trac-

tor's PTO. The winch input shaft is splined to plug directly into the tractor's PTO.

A high load on the winch will cause an increase in torque output and cable pull on winch drum (1). The hydraulic con-

trol valve controls input clutch (2) and directional clutches (3).

Input clutch (2) is a hydraulically activated disc-type oil clutch. There is no connection between the input shaft of the

clutch and the output gear (4) until oil pressure causes a solid connection between clutch plates and clutch discs

(engaged clutch). The operator moves a hand control lever to direct oil to the clutch to engage the clutch. Input clutch

(2) can be modulated to provide inching control in the reel-in mode. In order to handle the engagement and disengage-

ment modulation, the winch uses four disc assemblies and four plates in the input clutch. When the input clutch is

engaged, power goes through gears (4) to bevel gear and pinion (5).

A connection between bevel gear and pinion (5) and

center shaft (6) is made by the directional clutches (3).

The connection in clutches (3) is made by springs

holding the discs against the plates (clutches engaged).

Both clutches (3) are engaged until oil pressure of the

hydraulic control system moves the piston of one

clutch or the pistons of both clutches. This causes the

discs and plates to move apart (clutch disengaged).

Directional clutches (3) are so named because they

change the direction that the cable moves. Directional

clutches turn in opposite directions. When both are

engaged, the winch drum cannot turn. When the input

clutch is engaged, one directional clutch must be dis-

engaged. Disengagement of one clutch will cause the

winch to REEL IN. Disengagement of the other clutch

will cause the winch to REEL OUT.

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