ELEMENT A-A 7N9028 - Caterpillar

Hydraulic System
The winch contains an independent, internal hydraulic system. The winch housing serves as a reservoir and stores filtered oil for the internally mounted hydraulic pump. The pump is driven by a gear pressed onto the bevel pinion gear. The pump supplies oil whenever the PTO shaft is turning. Oil from the pump is routed through a pressure filter then directed to the control valve where a stand-by system pressure is maintained at 320-410 psi (2210-2830 kPa).The system oil pressure is routed through the control valve body to the Directional and Brake control cartridges. Movement of the Directional control spool opens passages which direct oil to apply the Reel-In or Reel-Out clutches and release the spring applied multi-disc oil brake.Movement of the Brake spool will direct oil to release the brake only. The movement of the spools responds to the position of the operators Power Shift control lever by means of flexible control cables. Winch controls with optional Free Spool.The winch hydraulic system is equipped with an accumulator. The accumulator stores a small amount of oil at system pressure to assist the application of the clutches and release of the brake under all operating conditions. The stored oil supply may also be used to release the spring applied brake whenever the tractor engine or torque converter is stalled. The accumulator stored oil supply is continuously refilled by the winch pump and valve whenever the PTO shaft is turning.On tractors which supply PTO power through the torque converter, it is possible to cause the torque converter to stall if the tractor engine speed is too low. It is important that engine idle speed be set to factory specifications.
Discharge accumulator oil supply before removing any hydraulic lines or servicing winch. Personal injury may result from sudden release of oil pressure. To discharge the accumulator, stop engine, slowly cycle Power Shift control handle into full Reel-In then Reel-Out positions a minimum of five (5) times.
Gear Train
The winch bevel pinion, bevel gears, hydraulic pump and clutch friction discs are rotating whenever the tractor PTO shaft is rotating. Application of a clutch, Reel-In or Reel-Out, and the simultaneous release of the brake will cause the rotation of the remaining gear train and cable drum. See illustrations below. The clutch shaft assembly (with bevel gears) must turn 40.4 times for one (1) rotation of the cable drum on a 4 shaft gear train winch and 22.3 times on a 3 shaft gear train winch.The direction of the tractor PTO shaft rotation and the right and left hand clutch location is determined by facing the rear of the tractor.The cable drum rotation may be easily changed from overwind (standard) to underwind by reversing clutch pressure lines at the control valve ports C1 and C2 and installing the wire rope in the opposite cable drum ferrule pocket.