EXTERNAL MAST 1078949 - Caterpillar

1. Put a mark (1) on the body and base. 2. Remove hex-head bolt (2). 3. Carefully pull base (3) away from body (4). Seals on the valves may make it hard to pull the base off. 4. Remove four outer springs (5). 5. Remove actuator plate (6) and the swivel. 6. Remove retainer (7) and plunger (8). There are four retainers and plungers. They pull out very easily. The plunger for No. 2 valve is different than the rest. Mark it to be sure it is installed correctly during assembly. 7. Remove plunger (8) from retainer (7). All four stems are the same. However, mark each one carefully with the number of the bore shown on the bottom of base (3).8. Remove valve stem (9). The following steps are for the assembly of the pilot control valve.9. Assemble the valve in reverse order of disassembly.10. Put valve stems back in the correct bores.11. Be sure the correct plunger is installed in valve No. 2. The cavity in plunger for valve No. 2 is deeper than the other valves.12. Do not tighten the swivel too much. A small amount of clearance between the actuator plate (6) and the plungers (8) is needed.13. Actuate each valve with the actuator plate. If all valves operate freely, the valve is ready to be installed in the machine.