JOINT 0337833 - Caterpillar

Illustration 1 g03344223
(1) Gear pump (hydrostatic charge, service brakes, differential lock)
(2) Gear pump (Steering, implement) The steering/implement pump (2) and the charge/brake/differential lock pump (1) are two pumps together as one unit. The gear pump assembly is mounted on the hydrostatic pump (1). Both pumps are fixed displacement gear type pumps and identical in operation. When the pump is viewed from the drive end, the pump shaft rotates in a clockwise direction.
Illustration 2 g03344259
Typical Fixed Displacement Gear Pump
(3) Drive gear
(4) Idler gear
(A) Outlet (High pressure)
(B) Inlet (Low pressure) A gear pump carries oil from inlet port (B) to outlet port (A) in the spaces between the gear teeth.The drive shaft turns drive gear (3). The drive gear forces idler gear (4) to rotate. When the gear teeth separate, a partial vacuum is formed. Oil fills in the spaces between the teeth inlet port (B). The gears carry oil around the circumference of the pump to outlet port (A). A seal is formed by the gear teeth against the pump housing. Oil is forced out of the spaces between the gear teeth as the gear teeth mesh together at outlet port (A). Oil will not return to inlet port (B) because the meshing of the gears will fill the spaces between the gear teeth.The flow rate of oil that is supplied by the pump is controlled by the rate of rotation of the shaft.