Abstract: A rotary fluid pressure device is disclosed comprising a housing having fluid inlet and outlet means and enclosing a gerotor having an internally toothed member and a coacting externally toothed member having a less number of teeth than the internally toothed member and having its axis positioned eccentrically relative to the axis of the internally toothed member. A wobble stick in the housing has a first end connected to the axial drive shaft and a second end connected to the gerotor member having the orbital movement. The housing has one set of passageways communicating at all times with the expanding and contracting gerotor cells. The gerotor member having orbital movement is, in addition to its usual function, a valve with two travel passageways, one travel passageway coaxially surrounding the other passageway.

Abstract: A rotary fluid pressure device is disclosed comprising a housing having fluid inlet and outlet means and enclosing a gerotor having an internally toothed member and a coacting externally toothed member having a less number of teeth than the internally toothed member and having its axis positioned eccentrically relative to the axis of the internally toothed member. A wobble stick in the housing has a first end connected to the axial drive shaft and a second end connected to the gerotor member having the orbital movement. The housing has one set of passageways communicating at all times with the expanding and contracting gerotor cells. The gerotor member having orbital movement is, in addition to its usual function, a valve with two travel passageways, one travel passageway extending straight through the rotor and coaxially surrounding the other travel passageway.

Abstract: A hydraulic device of the type in which an internally toothed first gear and an externally toothed second gear eccentrically located within said first gear are supported for relative rotary and orbital movement. The gear teeth of the first and second gears define pockets or chambers which expand from a minimum volume to a maximum and again contract to said minimum volume upon relative rotational and orbital movement thereof. A commutation valve arrangement in synchronism with said relative rotary and orbital movement connects the expanding pockets with one side of a fluid pressure system and connects the contracting pockets with the other side of the fluid pressure system. The commutation valve arrangement directs fluid to and from said pockets from one axial side thereof, and an additional valve arrangement is provided for directing fluid into the pockets from the other axial side thereof, the additional valve arrangement being responsive to the fluid pressure in the pockets.