DIFFERENTIAL GP 1378858 - Caterpillar

Sudden movement of the machine or the release of oil under pressure can cause personal injury. At operating temperature, the hydraulic oil is hot and under pressure. Hot oil can cause burns. To prevent possible personal injury, release the pressure in all of the implement circuits before any hydraulic lines or components are disconnected or removed.
1. Release the pressure in the hydraulic system as follows:a. Move the machine to a smooth horizontal location. Move away from working machines and personnel.b. Permit only one operator on the machine. Keep all other personnel either away from the machine or in view of the operator.c. Move the switch for the CUSHION-HITCH to the "LOCKDOWN" position. Be sure the rear bracket assembly of the hitch is down against (resting on) the front hitch assembly.d. Activate the parking and secondary brakes. Lower the bowl to the ground. Lower the apron. Stop the engine.e. Move all scraper control levers to all positions to release the pressure in the hydraulic system.f. Carefully loosen the fill cap on the hydraulic oil tank to release the pressure in the tank.g. Be sure all hydraulic pressure is released before any fittings, hoses or components are loosened, tightened, removed or adjusted. Wait at least five minutes after the machine is turned off. 2. Disconnect hose assemblies (1) and (2) from the steering servo sender cylinder. Put plugs in the hose assemblies to prevent oil loss and to keep dirt and debris out of the hydraulic system.3. Remove nuts (3) and (5). Remove steering servo sender cylinder (4). The weight of the steering servo sender cylinder is 17 kg (37 lb). The following steps are for the installation of the steering servo sender cylinder.4. Check the condition of the O-ring seals used in the ends of hose assemblies (1) and (2). If the seals are damaged, use new parts for replacement.5. Install the steering servo sender cylinder in the reverse order of removal.6. Check the oil level in the hydraulic oil tank. If necessary, fill the hydraulic oil tank with oil to the correct level. For the correct filling procedure, see the Operation & Maintenance Manual for 623F Elevating Wheel Tractor-Scrapers, SEBU6720.Disassemble & Assemble Steering Cylinder (Servo Sender)
Start By:a. remove steering cylinder (servo sender)1. Remove four bolts (17) and heads (8) and (22) from tube (10).2. Remove rod (15) and piston (20) from piston rod (13).3. Remove two seal assemblies (19) and wear ring (21) from piston (20).4. Remove head (8) from piston rod (13). 5. Remove O-ring seal (18) from head (8).6. Using Tool (A), remove retaining ring (1) from head (8).7. Remove retainer (3) and seal (9) from head (8).8. Remove rod wiper (16) from retainer (3).9. If necessary, remove bleeder screw (2) from head (8).10. Remove O-ring seal (4) from head (22).11. Using Tool (A), remove retaining ring (7) from head (22).12. Remove retainer (6) and seal (5) from head (22).13. Remove rod wiper (14) from retainer (6).14. If necessary, remove the bleeder screw from head (22).15.