It is an objective of the present invention to eliminate the causes of the VANE BOUNCING and the resultant intermittent LEAKAGE, as well as to reduce the overall NUMBER OF PARTS.

An oval/cycloidal housing of some proportion, either stationary or attached to a drive shaft. The oval housing is defined by a continuous arcuate wall surface including an inlet arc surface of progressively increasing radius in the direction of rotation of the rotor member, and a discharge arc surface of progressively decreasing radius.

Plates to enclose the oval housing sides.

Freely moving INTERSECTING CURVED VANES travel along the inside wall of the oval housing positioned in the guide-slots of the rotating cylinder passing through the guide slots independent with the rotor creating chambers between each pair of adjacent vanes. Vanes are arcs, not spring mounted, to eliminate bouncing as they pass along the arc surface of the oval housing.There is a relatively close fit between each slot and its vane. As a result, fluid is not readily communicated through the slot, past the vane. As the vanes retract into the central cylinder, they are cooled.

The pumping chamber is defined by a pair of inlet arc surfaces and a pair of discharge arc surfaces of progressively decreasing radius.

Cylinder/rotor rotating within the oval/cycloidal housing is slotted to guide and constrain the vanes in their occilating travel.

Connected to either the rotating oval housing or the rotating cylinder which is capable of transmitting rotary motion,through which the system is driven.

There are two oppositely disposed expanding fluid chambers, and two oppositely disposed contracting fluid chambers. It is "balanced" in the fact that the arrangement of the chambers results in balanced hydraulic forces acting on the rotor.