SERVICE MANUAL FOR WINCH MODELS PA55 & PA56 Caterpillar


Bevel Pinion and Hydraulic Pump Service

Usage:

The bevel pinion, bevel gears and hydraulic pump are turning whenever the tractor PTO shaft is turning. The bevel pinion transmits torque from the PTO shaft to the bevel gears, clutch shaft and winch gear train. Proper adjustment of bevel pinion/bevel gear back-lash and tooth contact pattern is essential for quiet operation and long component life.

The bevel pinion and hydraulic pump share common carrier housing. The carrier is mounted in the front face of the winch case and will be located in the upper bore for standard PTO winches and in the lower case bore of low PTO winches.

Bevel Pinion Carrier Removal

Drain oil from winch and remove the winch from the tractor as described in "Winch Removal and Installation" section of this manual. Leave the winch mounting adapter plates attached to the tractor where applicable.

Remove the 1/2 in. capscrews which secure the bevel gear inspection plate to the top of the winch case. Remove the inspection plate. Remove the pump suction tube and pressure hoses from the pump. Remove the capscrews (3) securing the carrier assembly to the winch case. Using two of the capscrews as "jackscrews", remove the carrier assembly. Retain the shim set (13, 14, 15) for reassembly.

Bevel Pinion Removal

Bend the tang of the lockwasher (4) away from the locknut (2) and remove the locknut (2) and lockwasher (4).

Support the carrier assembly in a suitable press. Place support blocks toward the outer diameter of the carrier. From the locknut end, press out the bevel pinion (16).

Remove the bearing cone set spacer from the bevel pinion. Position the bevel pinion assembly in a suitable press with support blocks under the pump drive pinion (10) as close to the bevel pinion gear as possible. Press the bevel pinion (16) free of the bearing cone and pump drive pinion.

Support the carrier in a vice and remove the oil seal (8), oil seal spacer (9) and o-ring (5).

Remove the oil seal retaining ring (7) and outer bearing cone. Remove the bearing cups, bearing cup retaining ring and the set spacer from the carrier.

Remove the retaining ring (19) and plug (20) from the end of the bevel pinion. Remove the o-ring (18) from the groove in the gear.

Thoroughly clean and inspect all parts at this time. All components of the bearing assembly are a matched set with the bearing adjustment controlled by the inner and outer set spacers. If the bearing cone or cup is worn or damaged, the entire bearing assembly (1) must be replaced.

Bevel Pinion Assembly

Lubricate and install o-ring (18) into the groove in the bore of the bevel pinion (16). Install plug (20) with chamfered edge toward the o-ring. Secure the plug in the pinion with the retaining ring (19).

NOTE: On bevel pinions equipped with a threaded plug, apply Loc-tite 242 or equivalent to socket head plug and tighten securely.

Clean and dry bore of pump drive pinion (10) and mating surface on bevel pinion (16) with Loc-tite primer or equivalent.

Apply Loc-tite 601 or equivalent to pump drive pinion bore and mating bevel pinion surface. Press pump drive pinion onto bevel pinion and seat securely against bevel pinion shoulder. Allow Loc-tite to harden.

Press one bearing cone of the bearing assembly (1) on to the bevel pinion and seat securely against the pump drive pinion. Install bearing cone set spacer on to the bevel pinion.

Install the bearing cup retaining ring into the groove in the carrier bore.

Place the carrier assembly onto bench with the pump side facing up. Install one bearing cup of bearing set (1) and seat against the retaining ring.

Turn the carrier over so that the pump side faces down. Install the bearing cup spacer with the shoulder inside of the retaining ring. Install the remaining bearing cup and seat firmly against the bearing cup spacer and retaining ring.

Place the carrier over the bevel pinion so that the pump side bearing cup seats on the bearing cone.

Press the remaining bearing cone securely onto the bevel pinion, seating into the bearing cup.

Lubricate and install o-ring (5) onto the bevel pinion against the bearing cone. Install seal spacer (9) over the bevel pinion with internal tapered edge toward the bearing cone and o-ring.

Install the oil seal retaining ring (7) into the carrier bore groove. Apply non-hardening sealant to the outside surface of the oil seal (8) and install the oil seal firmly against the retaining ring (7).

Install the bearing lockwasher (4) and locknut (2) onto the bevel pinion. Tighten the locknut to 150 lb-ft (203 N·m) torque and bend tang of lockwasher (4) into slot of locknut.

Bevel Pinion Carrier Installation

Apply gear tooth marking compound to bevel pinion and install carrier assembly into winch case using the original shim set. Replace gasket as required. Tighten capscrews to 75 lb-ft (102 N·m) torque.

Rotate bevel pinion in same direction as PTO shaft rotation and check bevel pinion/gear tooth contact pattern.

See typical contact patterns, next page.

Remove carrier assembly to add or remove shims to obtain the correct tooth contact pattern illustrated below.

Refer to Clutch Shaft Service for bevel gear backlash adjustment procedure.

Upon final installation of carrier assembly, apply non-hardening thread sealant to capscrews and tighten to 75 lb-ft (102 N·m) torque.

Refill winch to proper level with recommended lubricant.

Hydraulic Pump Service

The hydraulic pump supplies oil to the control valve to recharge the accumulator, apply clutches, release the brake, and lubricate critical components. Maintaining adequate oil flow is critical to reliable winch operation.

Pump flow should be tested with an accurate, commercially available flow meter. If a flow meter is not available, a serviceable flow meter may be fabricated from a gate valve, tee and gauge as listed below.

* Gate valve - 1/2 NPT port minimum, 1000 PSI (6,895 kPa) rating, minimum.
* 1/2 NPT schedule 80 pipe tee with a -8JIC hose adapter on one run.
* Accurate 0-600 PSI (0-4,137 kPa) gauge.

Attach 1/2 NPT run end of tee to gate valve with -8JIC adapter on opposite run.

Install gauge to branch of tee.

Test Procedure

1. Operate tractor and winch long enough to bring oil up to operating temperature. Stop engine.

2. Remove access cover on right hand side of winch and locate pump port on control valve labeled "P". Remove -8JIC pump line from the tee in the pump port of the control valve.

3. Attach pump line to the gauge side of the gate valve or flow meter. Direct the open end of the gate valve/flow meter back into the winch case.

4. With gate valve/flow meter fully open, operate engine at 650-700 RPM and measure oil flow by directing oil into a container for 15 seconds.

5. Gradually close gate valve/flow meter until you have applied 350 PSI (2413 kPa) load to the pump. Again record the flow for 15 seconds.

The minimum acceptable pump flow is 2 gpm (US) (7.6 lpm) at 650-700 RPM PTO speed and 350 PSI (2413 kPa). Two quarts (2 liters) per 15 seconds equals 2 gpm.

If pump flow is below minimum:

1. Check/verify PTO speed and accuracy of tachometer.

2. Check suction strainer for restriction.

3. Check suction hose for cracks or poor connection.

4. Pump is worn and requires replacement.

Hydraulic Pump Removal

Remove the 1/2 in. capscrews which secure the bevel gear inspection cover to the top of the winch case. Remove the inspection plate. Remove the pump suction tube and pressure hose from the pump. In most applications, the pump may be removed from the bevel pinion carrier through the top of the winch case. If this is not practical in your application, then remove the bevel pinion carrier from the winch case as described in the "Bevel Pinion Carrier Service" section of this manual.

All Units

Remove the four capscrews and lockwashers (5, 6, 7) securing the pump to the bevel pinion carrier.

Remove the pump assembly and wear plate (1) from the bevel pinion carrier.

Thoroughly clean and inspect all pump components at this time. If there is any sign of damage or wear which may reduce pump performance, the entire pump assembly must be replaced.

Pump Installation

Lubricate entire pump assembly with recommended oil.

Coat the capscrew threads with Loc-tite 242 or equivalent and evenly tighten to 100-110 lb-in by 25 lb-in (11.3-12.4 N·m by 2.8 N·m) increments in a cross pattern.

When properly installed, there will be a slight gap, .005-.040 in. (.13-1.02 mm) between the mounting ears of the pump housing and the bevel pinion carrier. This condition insures that the pump housing is clamped and sealing against the wear plate.

Apply non-hardening thread sealant to the pipe threads and install the suction (3, 4) and pressure (2) hose adapters as follows:

A. For counter-clockwise (ccw) bevel pinion rotation, the most common, install the pressure adapter into "A" port.
B. For clockwise (cw) bevel pinion rotation, install the pressure adapter into "B" port.

NOTE: Determine direction of bevel pinion rotation when viewed from rear of winch looking forward toward the tractor.

Install suction tube assembly (standard PTO) or suction hose and clamp (low PTO) securely to the pump suction port.

Install the pressure hose securely to the pump pressure port and make certain the hose is routed away from the bevel gears and clutch housing to avoid chaffing and failure.

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