GRILL 4767682 - Caterpillar

Illustration 1 g02647176
Right Side of Machine (1) Left lower pump stackThe hydraulic pumps are located on the right side of the machine. The right side compartment door provides access to these components. The auxiliary pump is located in left lower pump stack (1). The auxiliary pump is an axial piston pump. The pump has a variable displacement. The pump is pressure compensating.
Illustration 2 g02647177
Cross Section of Auxiliary Pump (2) Pressure compensator spool (3) Valve plate (4) Cylinder block (5) Bias piston (6) Swashplate (7) Bias spring (8) Input shaft (9) Piston (10) Slipper padThis cross sectional view of the auxiliary pump shows the major pump components. When the auxiliary pump is at rest, bias spring (7) forces bias piston (5) to move swashplate (6) to the maximum angle. Engine rotation turns pump input shaft (8), which then rotates the rotating group. The rotating group contains cylinder block (4) and pistons (9). The pistons in the groups rotate with the cylinder block. Piston slipper pads (10) allow the pistons to follow the angle of the swashplate.As slipper pads (10) follow the angle of swashplate (6), pistons (9) move in and out of cylinder block (4). As a piston moves out of the cylinder block, oil from the hydraulic tank is drawn into the piston chamber. As a piston moves into the cylinder block, oil is forced out of the piston chamber.Pump supply oil flows into the pump control valve. Supply oil acts against pressure compensator spool (2) in opposition to the spring. The pressure compensator spool moves against the spring force. This movement opens a passage for pump supply oil to flow into the chamber of bias piston (5). Pressure in the bias piston chamber causes the servo piston to move swashplate (6) against the force of the bias spring. This movement reduces the angle of the swashplate.Pressure compensator spool (2) maintains pump output at a constant pressure.