A hydrostatic module is disclosed, including a pair of shafts rotatably supported
by a frame. Two yokes are pivotally mounted on the frame, each having complimentary
surfaces to the other yoke and to the frame, minimizing the space occupied by the
yokes. Stop means are provided on the yokes and on the frame to limit the pivotal
movement of the yokes. A hydrostatic power unit is carried by each yoke, each connected
to one of the shafts. A control system, having a single piece control housing containing
servo pistons, pivots the yokes. The servo pistons independently determine the
orientation of the yokes. A single piece fluid control porting plate is secured
to the control housing to route hydraulic fluid to multiple locations within the
control housing. A fluid manifold serves as a main structural element, with intimate
proximity between the manifold and the control housing allowing simplified fluid
exchange therebetween.