PIN 1B0851 - Caterpillar

START BY:a. remove hydrostatic power control unitb. remove charge pump (fixed displacement)c. remove charge and main relief valves There are two procedures described in which the pump head is removed. The first method described is used in a complete HPCU disassembly. The second procedure is used only when the pump head and/or barrel assemblies are to be removed for specific troubleshooting problems. 1. Remove the top cover from the hydrostatic power control unit. 2. This step is for a 953 hydrostatic power control unit only. Install two 1/4"-20 NC bolts in cap (1). Use a crow foot bar to remove both caps (1). Remove bolt (3) and snap ring (4) and the washer. Remove levers (5) as a unit. Remove the bolt in lever (6), and remove the lever. Remove both keys from the shafts.3. Remove plug (2) and the spring from both sides of the pump head. 4. Install a 1/4"-20 NC bolt in pin (8). Use a screwdriver to hold eye (7) of the servo cylinder straight so pin (8) can be removed far enough to disengage from the eye of the servo cylinder. Disengage the pin in the eye of the other servo cylinder in the same way.
The pump head holds large springs in the pump barrels in compression. The pump head can be pushed away from the case very rapidly if the spring tension is not released before the last bolt is removed from the pump head. To gradually release the spring tension, be sure the pump head moves away from the case as the bolts in the pump head are loosened. The bolts in the pump head are long enough to release all the tension in the springs before the bolts are removed.
5. Install two 1/2"-13 NC forged eyebolts, or fasten tooling (B) to head (9), and fasten a hoist. Remove the bolts that hold the head in place.
When the pump head is removed, do not let the port plates fall from the pump head. The port plates are made of brass and are easily damaged. Give extra protection to both sides of the port plates and the surface of the pump head and pump barrels that comes in contact with the port plates.
6. Remove the pump head. Weight is approximately 99 kg (220 lb.). 7. Install protective plates (A) on both pumps as protection for the barrels from any damage. Use oil or grease to hold the protective plates in position on the pump barrels. Keep the protective plates on the barrels at all times. 8. Remove port plates (10) and the four dowels from the pump head. Put identification on the port plates for correct installation.Install Pump Head
1. Use a piece of wire to clean oil holes (1) in the pump head. 2. Install dowels (3) in the pump head. Put clean grease on the pump head to hold the port plates in position when installed. Install port plates (2) in their original position on the pump head.3. In addition to