CRANKSHAFT GP 0R4688 - Caterpillar

The accumulator stores oil at system pressure. The primary function of the accumulator is to cushion pressure surges in the hydraulic system and aid in brake release and clutch application. The accumulator also stores enough oil for the operator to release the brake when the tractor PTO is stalled or the tractor engine stops. The spring-type accumulator DOES NOT require any periodic recharging or servicing. Piston Seal Test Procedure
1. If the accumulator is installed in the winch case, remove the accumulator hose from the "A" port of the control valve. The accumulator may then be tested in the winch case.2. Connect a hand pump with accurate 0-600 PSI (0-4137 kPa) gauge and shut-off valve to the accumulator. Apply 400 PSI (2758 kPa) to the accumulator. Close shut-off valve securely. Measure rod extension beyond rod guide. If rod extension decreases more than 1/8 in. (3 mm) in one minute, the accumulator should be disassembled and new seals installed. If piston seal ring inspection or replacement are required, carefully follow the procedure listed below.1. Secure the accumulator tube in a hydraulic press in such a manner to prevent side movement.2. With a tubular mandrel, press rod guide (3) approximately 1/2 in. (13 mm) into tube (8) to provide access to retaining ring (2). Carefully remove retaining ring (2) from the groove in the tube. Discard retaining ring.3. Slowly release pressure on the press and remove rod guide (3), spring (4) and piston/rod assembly. The cast iron piston ring (6) will attempt to expand into the retaining ring groove when the piston is removed from the tube. To reduce the chances of this happening, pack the groove with heavy grease and withdraw the piston rod assembly quickly past the groove.4. Inspect or replace piston seals (6 and 7) as required. While the accumulator is disassembled, check the piston retaining nut (9). It should be tightened to 120 lb-ft (163 N m) torque.5. Lubricate tube and piston seals with winch lubricant. Install an automotive type piston ring compressor around the piston making certain the step cut piston ring is properly compressed.6. Press piston into tube and push to bottom of tube. Install spring and rod guide.7. With the tube secured in a press, press rod guide into tube approximately 1/2 in. (13 mm) below the outer edge of the tube. Install a new retaining ring (2) securely into the groove in the tube.8. Slowly release pressure on the press. Observe that the rod guide has fully seated the retaining ring into the groove.9. Retest piston seals to make certain seals were not damaged during installation.