CONTROL-REFUELING PUMP 2720710 - Caterpillar

Illustration 1 g01334167
Typical hydraulic pump
(1) Pump drive shaft
(2) Pistons
(3) Control piston
(4) Barrel
(5) Inlet opening from the hydraulic tank
(6) Outlet opening to the combination valve
(7) Pump control valve
(8) Bias spring
(9) Retraction plate
(10) Slipper
(11) Swashplate The hydraulic pump is a variable displacement axial piston pump.The hydraulic pump has nine pistons (2). When drive shaft (1) turns, barrel (4), slippers (10) and retraction plate (9) turn. The piston ends connect to the slippers. Swashplate (11) does not turn. There is a bearing journal on each side of the swashplate. The two bearing journals are inside bearings which allow movement of the swashplate. Oil flow through the passages in the pistons lubricates the internal components of the pump.When swashplate (11) is at the maximum angle and drive shaft (1) is turning, pistons (2) are moved in and out of barrel (4). As the pistons move out of the barrel, the pistons create a vacuum at inlet opening (5). The pressure in the hydraulic tank pushes the oil into the inlet opening. The oil passes through the inlet opening and into the piston bore in the barrel. As the barrel continues to turn, the pistons are pushed into the barrel as the slippers rotate up the angle of swashplate (11). The pistons push the oil from the piston bore through pump outlet opening (6) and into the combination valve.When the engine is operating, the pump will produce flow in order to satisfy the following conditions:
The demand of the steering system
The margin pressure of the pump
The demand of the hydraulic implements
The internal lubrication of the pump components