Patent ID: 7040092

Claim:
A center section assembly for mounting inside the housing of a hydrostatic drive apparatus, comprising: a pump support portion comprising a pump running surface and a first mating surface; a motor support portion comprising a motor running surface and a second mating surface; hydraulic porting comprising: a pair of pump kidney ports formed on the pump running surface; a first pair of hydraulic ports formed in the pump support portion, where each of the first pair of hydraulic ports has a first end open to one of the pump kidney ports and a second end open at the first mating surface; a pair of motor kidney ports formed on the motor running surface; and a second pair of hydraulic ports formed in the motor support portion, where each of the second pair of hydraulic ports has a first end open to one of the motor kidney ports and a second end open at the second mating surface, whereby each of the second ends of the first pair of hydraulic ports is open to a corresponding second end of the second pair of hydraulic ports; and a raised surface formed on one of the first mating surface or the second mating surface to contact the opposite mating surface when the pump portion is joined to the motor portion whereby the raised surface assists in sealing the hydraulic porting.