OIL 7X7611 - Caterpillar

Illustration 1 g00970480
(1) Soft stop for destroke (2) Piston travel (3) Barrel (4) Stop screw for maximum angle (5) Bleed plug (6) Swashplate (7) Drain plug (8) Hydraulic horsepower regulator (9) Stop screw for minimum angle (10) Main pump regulator (11) Actuator piston (12) Maximum angle piston (13) Piston (14) Minimum angle piston (15) Control pressure plug (16) Destroke rodIllustration 1 shows the internal components of the main pump. The main pump is a variable displacement piston pump with a swashplate that is directly mounted to the engine flywheel housing. The pump is driven by a flexible coupling. The pump is self-priming.The pump generates flow when pistons (13) in the rotary group ride on the inclined surface of swashplate (6). Maximum angle stop screw (4) determines the maximum pump flow. Minimum angle stop screw (9) only keeps the pump flow from going over center during minimum operating angle actuation. The minimum pump flow is fixed by the length of the destroke rod (16) and the position of the opening to the passage inside the maximum angle piston (12) .When maximum angle piston (12) is moved to the left, swashplate (6) approaches the minimum displacement angle. As swashplate (6) approaches the minimum displacement angle the destroke pressure begins to progressively bleed off through the passage into the pump case. Progressively bleeding off the destroke pressure softly stops swashplate (6) before the swashplate makes contact with minimum angle stop screw (9) .Minimum angle stop screw (9) prevents excessive destroking of the pump, but the minimum angle stop screw does not determine the minimum displacement angle. The output flow is proportional to the rpm and to the swashplate angle. The pump regulator determines the amount of pump flow by regulating the oil pressure that is supplied to maximum angle piston (12) .Component and Location
Illustration 2 g00924170
M322C pump compartment (10) Main pump regulator (17) Swing pump regulator (18) Main pump (19) Fan drive pump (20) Charge pump (21) Swing pump
Illustration 3 g00924171
M316C and M318C pump compartment (10) Main pump regulator (17) Swing pump regulator (18) Main pump (19) Fan drive pump (20) Charge pump (21) Swing pumpThe two hydraulic pumps are mounted in tandem. The nearest pump to the engine (front pump) is main pump (18). Main pump (18) supplies flow to all of the implement and travel circuits.The main pump control (10) consists of the following separate sections:
Load sensing regulator (not shown)
Hydraulic horsepower regulator (8) The load sensing regulator uses the load sensing signal pressure from the main control valve in order to regulate the pump flow. The pump output is held at 2000 to 2200 kPa (290 to 320 psi) above the load sensing signal pressure. The pressure difference between the pump output and the load sensing signal pressure is called the margin pressure. The load sensing signal is supplied by the main control valve. The load sensing signal pressure is the highest implement pressure in the entire main hydraulic system. The load sensing regulator uses the load sensing signal in order to