Patent ID: 7516615

Claim:
A hydraulic drive system for a vehicle, wherein the vehicle includes a set of wheels mounted on opposite sides of a center line of the vehicle, the drive system comprising: a source of propulsive hydraulic fluid, wherein the source comprises at least two rotatable hydraulic pumps, each pump disposed in a separate pump housing, and the two pump housings being mounted on opposite sides of the vehicle center line, and the source is configured to permit symmetric application of components of the hydraulic drive system about the vehicle center line; and a pair of hydraulic motors, each motor disposed in a separate motor housing and in fluid communication with one of the hydraulic pumps, and each motor is engaged to one of the wheels to provide force thereto wherein the source comprises a plurality of system ports oriented parallel to, and disposed across a first plane perpendicular to, the vehicle center line and at least one bypass valve oriented parallel to the system ports and disposed across a second plane parallel to the first plane.