Oil Delivery

NOTE: For oil delivery description of the vane portion of the tandem pump, refer to Standard Pump.





NOTE: Numbers in parentheses ( ) indicate a component or tool in the associated illustration.

The spring-loaded pistons (5) more axially due to rotation of the eccentric drive shaft (3). With the travel of the piston to the lower dead-center position, a vacuum is created due to the increase in volume in the piston chamber. This causes the oil to flow in through the transverse bores in the piston which connects the cylinder chamber to the inlet side shortly before the lower dead-center position. On the power stroke the full cylinder chamber is sealed due to the overlapping of the bores shortly after the lower dead-center position.

Oil is pushed out to the pressure side via spring loaded exhaust valves. Constant oil flow at variable speed is achieved by suction control. As speed increases, the opening time of the transverse bores in the piston is reduced so that the suction vacuum is no longer adequate to completely fill the cylinder chamber in the short time interval. The decreasing partial filling has the effect of keeping the flow rate as well as the required power almost constant as speed increases.