Patent ID: 7588119

Claim:
A hydrostatic retarder pump and motor apparatus for a vehicle comprising: a housing; a shaft rotatably supported by the housing, said shaft including a first eccentric portion and a second eccentric portion; a plurality of pistons disposed within the housing, said plurality of pistons engageable with said first eccentric portion, said plurality of pistons selectively connectable with one of a low pressure accumulator and a high pressure accumulator; and a plurality of valves disposed within the housing, said plurality of valves being configured to selectively connect the plurality of pistons with the low pressure accumulator or the high pressure accumulator; wherein the second eccentric portion is engageable with the plurality of valves; and wherein shaft rotation may be implemented to drive the plurality of pistons and thereby transfer hydraulic fluid from the low pressure accumulator to the high pressure accumulator such that resistance is applied to the shaft and vehicle output is retarded, and further wherein hydraulic fluid from the high pressure accumulator may be implemented to drive the plurality of pistons and thereby power the vehicle.