A hydraulic device having a plurality of cylinders for distributing a flow of hydraulic fluid between a reservoir and a load, the device comprising: a housing having the plurality of cylinders with a plurality of corresponding pistons configured for reciprocation of a constant stroke length; an input port of the housing fluidly connected to each cylinder of the plurality of cylinders, the input port facilitating introduction of the hydraulic fluid into said each cylinder; an output port of the housing connected to said each cylinder, the output port facilitating the ejection of the hydraulic fluid from said each cylinder during the reciprocation, the output port configured for fluidly coupling said each cylinder to the load; and a distributor coupled to a main shaft of the hydraulic device, such that the distributor rotates in conjunction with the main shaft, the distributor having a distributor body including a first port configured for fluid communication with the input port and a second port configured for fluid communication with the output port; wherein the first port and the second port are fluidly coupled to the input port and the output port external to a shaft body of the main shaft.

A hydraulic device having a plurality of cylinders for distributing a flow of hydraulic fluid between a reservoir and a load, the device comprising: a housing having the plurality of cylinders with a plurality of corresponding pistons configured for reciprocation of a constant stroke length; an input port of the housing fluidly connected to each cylinder of the plurality of cylinders, the input port facilitating introduction of the hydraulic fluid into said each cylinder; an output port of the housing connected to said each cylinder, the output port facilitating the ejection of the hydraulic fluid from said each cylinder during the reciprocation, the output port configured for fluidly coupling said each cylinder to the load; and a distributor coupled to a main shaft of the hydraulic device, such that the distributor rotates in conjunction with the main shaft, the distributor having a distributor body including a first port configured for fluid communication with the input port and a second port configured for fluid communication with the output port; wherein the first port and the second port are fluidly coupled to the input port and the output port external to a shaft body of the main shaft.

A variable displacement pump-motor includes a pump-motor having a plurality of cylinders and pistons, and further including a main shaft rotatable relative to the system body. A hydro mechanical control system includes a plurality of main stage valves in communication with the plurality of cylinders. Each of the main stage valves is configured to open and close a cylinder of the plurality of cylinders to one or more of high or low pressure fluid sources. A pilot spool valve is in selective communication with each of the main stage valves. The pilot spool rotates with the main shaft. The pilot spool includes coding configured to operate each of the main stage valves to open and close the respective cylinders to the one or more high and low pressure fluid sources according to a translational position of the pilot spool and rotation of the pilot spool by the main shaft.

An axial reciprocation device having a main piston and an anchor piston coupled to one another via a swivel joint interconnecting 20 a pair of connecting rods, the main piston positioned in a main cylinder bore and the anchor piston positioned in an anchor piston bore of a housing, such that the main piston is configured for axial reciprocation in the main cylinder bore; wherein variable positioning of the anchor piston along the anchor piston bore results in variable displacement of the main piston of hydraulic fluid with respect to an inlet/outlet port of the housing.

A variable displacement pump-motor includes a pump-motor having a plurality of cylinders and pistons, and further including a main shaft rotatable relative to the system body. A hydro mechanical control system includes a plurality of main stage valves in communication with the plurality of cylinders. Each of the main stage valves is configured to open and close a cylinder of the plurality of cylinders to one or more of high or low pressure fluid sources. A pilot spool valve is in selective communication with each of the main stage valves. The pilot spool rotates with the main shaft. The pilot spool includes coding configured to operate each of the main stage valves to open and close the respective cylinders to the one or more high and low pressure fluid sources according to a translational position of the pilot spool and rotation of the pilot spool by the main shaft.