Bent Axis Hydraulic Pump: With this type of hydraulic pump, the cylinder barrel is driven by the pistons which in turn are themselves driven by the drive flange. The cylinder barrel is located and guided at its periphery by either a centre pin or a needle bearing, and is pivoted with reference to the shaft horizontal axis. The displacement volume changes in accordance with this pivot angle. Reversible hydraulic pump can be realised using this principle.
The pistons and the drive flange are connected by means of a ball·joint connection. This pulls out the pistons during the suction phase and forces them back into the piston bores in the cylinder during the pressure phase. A further knuckle joint is necessary between the actual pistons themselves and the ball-joint connection. (Compensation of the elliptical orbit and the circular orbit.) The separation of the suction and pressure sides is by means of a slot control as in the bent-axis hydraulic pump. The control plate, which can be either flat or spherical depending upon the particular design, pivots together with the cylinder barrel. In other words, the pressure connection must be routed through the swivel bearing. Oil is drawn in during the suction phase directly from the hydraulic pump chamber (this applies for versions with only one direction of delivery).