Patent ID: 7007468

Claim:
A hydraulic drive apparatus, comprising: a housing forming an oil sump; a center section mounted in the sump and comprising a pump running surface and a motor running surface formed thereon and hydraulic porting formed therein; a rotatable pump cylinder block mounted on the pump running surface and a rotatable motor cylinder block mounted on the motor running surface, wherein the pump cylinder block and motor cylinder block are hydraulically connected through the hydraulic porting; a pair of check valves mounted in the center section; an oil gallery located adjacent to the check valves and separate from the oil sump; and a charge pump located in a charge pump plate mounted on the center section adjacent to and separate from the pump cylinder block, wherein the charge pump is in fluid communication with both the oil sump and the oil gallery, and the charge pump is powered by rotation of the pump cylinder block and provides pressurized fluid to the oil gallery.