Modular hydrostatic transmission

A hydrostatic transmission comprising:

• a center section having a pump running face for interfacing with a pump, and a motor running face for interfacing with a motor;
• a pump that interfaces with the center section against the pump running face;
• a motor including a motor housing and an internal rotor set, wherein the motor housing is secured to the center section adjacent to the motor running face in a manner that permits rotation of the rotor set;
• a bearing supported by the motor housing;
• and
• a top housing that encloses the center section, pump, and motor;
• wherein:
• the center section forms an end cover for the motor housing to which the motor housing is secured, the end cover including the motor running face adjacent to the internal rotor set, and the motor running face having motor kidney ports that open into the motor housing;
• the center section forms a porting manifold for communicating hydraulic fluid to the motor;
• the porting manifold comprising at least two internal passages between pump kidney ports on the pump running face and motor kidney ports on the motor running face, and the motor kidney ports are raised in elevation relative to the pump kidney ports;
• and
• the internal passages run parallel to each other as they rise in elevation between the pump kidney ports and the motor;
• and
• wherein the center section forming the end cover and the porting manifold is a unitary member.