Abstract: A displacement pump, including a pump chamber and a regulating chamber which are separated from each other by a piston, wherein the pump has a device with which fluid flowing from the pump chamber toward the regulating chamber can be drained.

Abstract: A rotary pump with an improved seal on a control pressure chamber, including: a housing having a delivery chamber; a feed wheel rotatable in the delivery chamber; an actuating member surrounding the feed wheel forming delivery cells and moveable in the housing relative to the feed wheel. The control pressure chamber is delineated by the actuating member together with axially facing axial co-operating surfaces, forming an axial sealing gap and a radial sealing gap. A control fluid can be introduced into the control pressure chamber for applying pressure to the actuating member to exert an actuating force in the actuating direction; a restoring device for generating a restoring force; and a sealing element arranged on the actuating member or the circumferential co-operating surface. To compensate for a change in gap width of one of the axial sealing gaps, a base leakage cross-section is provided on the sealing element.

Abstract: A displacement pump, including a pump chamber and a regulating chamber which are separated from each other by a piston, wherein the pump has a device with which fluid flowing from the pump chamber toward the regulating chamber can be drained.