Variable displacement pump-motor

A variable displacement pump-motor system comprising:

• a pump-motor including a plurality of cylinders and a plurality of pistons slidably received in the cylinders, the pump-motor includes:
• a system body including the plurality of cylinders, and
• a main shaft rotatable relative to the system body;
• a hydromechanical fluid control system comprising:
• a plurality of main stage valves in communication with the plurality of cylinders, respectively, each of the main stage valves is configured to open and close a respective cylinder of the plurality of cylinders to one or more of a high pressure fluid source or a low pressure fluid source,
• a pilot spool valve in selective communication with each of the main stage valves with respective pilot connection ducts, the pilot spool valve includes a pilot spool configured for rotation and translation within the system body, and the pilot spool rotates with the main shaft, and
• wherein the pilot spool includes coding configured to operate each of the main stage valves to open and close the respective cylinders to one or more of the high pressure fluid source or the low pressure fluid source according to a translational position of the pilot spool and rotation of the pilot spool by the main shaft.