PLUNGER AS. 4V0308 - Caterpillar

1. Release the pressure in the implement hydraulic circuits (the boom, the stick, the heel and the grapple) before any of the hydraulic lines or the components are disconnected or removed. Release the pressure as follows: a. Start the machine, and fully extent the stick cylinder.b. Adjust the position of the grapple so that it will be stable on the ground when the boom is lowered.c. Lower the boom until the grapple is flat on the ground.d. Stop the engine.e. Place the engine start switch key to the "ON" position without starting the engine.f. Put the hydraulic activation control lever in the "UNLOCK" position.g. Move the control levers for the boom, the stick, the swing, the heel and the grapple to all full stroke positions. This will release any pressure that might be present in the pilot system.h. Place the engine start switch key to the "OFF" position.i. Slowly loosen the pressure valve cap on the hydraulic tank and release the pressure.j. Tighten the on the hydraulic tank.k. The pressure in the hydraulic system has been released and the lines and the components can be removed. 2. Open the access door of the cab riser. Lock the door in the "Open" position. Remove four bolts and washers (1) that secure the cab assembly to the frame. Tilt the cab all the way forward to gain access to the pilot control valve (travel).
View From Under Cab Oil will drain from the six hose assemblies that are connected to the travel pilot control valve when they are disconnected. Place a drain pan under the travel pilot control valve to contain the drain oil.3. Put identification marks on hose assemblies that are connected to the pilot control valve (travel) so they can be reinstalled in their original locations. Disconnect six hose assemblies (3) from pilot control valve (2). Put plugs in the hose assemblies to keep contaminants out of the hydraulic system. 4. Remove hose filter assembly (4) from pilot control valve (2). 5. Remove the rubber floor mat (5) from the cab to gain access to the pilot control valve.6. Remove four bolts (6) and the washers that hold pilot control valve (1) to the cab floor. Remove the control lever assemblies, the pedal assemblies and travel pilot control valve (2), as a unit, from the machine. The following steps are for the installation of the pilot control valve (travel).7. Put pilot control valve (2) in position in the cab floor. Install bolts (6) and the washers that hold the pilot control valve to the floor.8. Install rubber floor mat (5) in the cab.9. Install hose filter assembly (4) in pilot control valve (2). Check the condition of O-ring seals used in the ends of the six hose assemblies. If any of the seals are damaged, use new parts for replacement.10. Connect six hose assemblies (3) to pilot control valve (2).11. Tilt the cab assembly back in position. Install four bolts (1) and tighten. Refer to the topic "Lubricant Viscosities