Abstract: A hydraulic motor has a longitudinally extended piston cylinder divided longitudinally into two separate and distinct fluid passages by a central divider. Longitudinally midway about the extended piston cylinder is attached a large center piston which provides the primary driving force for operation of the hydraulic motor. Pressurized fluid passes through one fluid passageway formed by the extended cylinder and central divider, and then through ports formed in the piston cylinder into a chamber. The pressurized fluid drives the large center piston, and therefore the piston cylinder, towards the source of fluid pressure being admitted into the piston cylinder. Pressurized fluid is thereby ported from a pressure chamber through the cylinder beyond the longitudinal midway point, and then passed through the cylinder wall to the power piston surface.

Abstract: A hydraulic motor has three interconnected power pistons. The pistons include passageways therebetween that allow a working fluid to be conserved upon reciprocating piston motion. Valves control the pressure state of working fluid within working chambers, which in turn will cause the three piston assembly to oscillate within the working chambers. The hydraulic motor is combined with a pressure source and an energy converter to form a hydraulic-pneumatic power plant. The energy converter converts pressurized working fluid from a single port into pressurized fluid passed through a first port and reduced pressure fluid passed through a second port. The pressure source is preferably pneumatic, which provides the necessary store of energy, or push, to initiate motion within the hydraulic motor.