Abstract: A linear pump assembly includes a cylinder piston disposed in a generally tubular internal cylinder chamber defined within a cylinder housing having first and second ends, a first plunger-cylinder rod securely coupled to a first end of the cylinder piston and disposed in a first generally tubular internal plunger chamber defined within a first plunger housing in linear alignment with the cylinder housing, and a second plunger-cylinder rod securely coupled to a second end of the cylinder piston and disposed in a second generally tubular internal plunger chamber defined within a second plunger housing in linear alignment with the cylinder housing and the first plunger housing. First and second fluid ends are coupled to the first and second plunger housings respectively, the first and second fluid ends each housing a suction valve and a discharge valve.

Abstract: A closed-circuit, self-contained hydraulic axis includes an electric motor, a hydraulic cylinder configured to be connected to a load and a main pump driven by the electric motor to pump hydraulic fluid through the circuit. Pressure connections of the pump are connected to the respective chambers of the cylinder such that the cylinder rod is configured to extend and retract depending on a direction of flow of the hydraulic fluid through the main pump. The hydraulic axis includes a main accumulator connected to the pump via first control valve, an energy storage accumulator connected to the pump via a second control valve, and a charge pump. The hydraulic axis is switchable between a first operating mode that is free of energy storage in the energy storage accumulator, and a second operating mode in which energy is stored in the energy storage accumulator.

Abstract: A hydraulic circuit includes a prime mover that is configured to generate an oscillating flow of hydraulic fluid, and an actuator that is driven by the prime mover and configured to provide oscillating motion and to be connected to a load in each direction of the motion. The hydraulic circuit also includes a reclamation device that is disposed in the hydraulic circuit between the prime mover and the actuator. The reclamation device captures and stores a portion of hydraulic fluid displaced from the actuator during a transition between opposed motions, where the portion of hydraulic fluid corresponds to an amount of hydraulic fluid equal to a volume of fluid required to compensate for compression of fluid within the hydraulic circuit due to system pressure and load pressure. The stored fluid is used by the circuit in a subsequent motion.

Abstract: A closed-circuit, self-contained hydraulic axis includes an electric motor, a hydraulic cylinder configured to be connected to a load and a main pump driven by the electric motor to pump hydraulic fluid through the circuit. Pressure connections of the pump are connected to the respective chambers of the cylinder such that the cylinder rod is configured to extend and retract depending on a direction of flow of the hydraulic fluid through the main pump. The hydraulic axis includes a main accumulator connected to the pump via first control valve, an energy storage accumulator connected to the pump via a second control valve, and a charge pump. The hydraulic axis is switchable between a first operating mode that is free of energy storage in the energy storage accumulator, and a second operating mode in which energy is stored in the energy storage accumulator.

Abstract: A rotary electrohydraulic actuator includes a direct drive hydraulic motor having an output shaft through opening that is concentric with a rotational axis of a rotor of the hydraulic motor. The actuator includes a power plant mounted on the hydraulic motor via a manifold. The power plant includes an electric motor driven hydraulic pump. Operation of the electric motor causes the hydraulic pump to supply pressurized fluid to the hydraulic motor. The power plant is compactly mounted to the manifold so that a longitudinal axis of the electric motor is parallel to and spaced apart from the rotational axis of the hydraulic motor.

Abstract: An electro-hydraulic compact drive for underwater use and for driving an output element includes a hydraulic motor, a hydraulic pump, and an electric motor as components of the electro-hydraulic compact drive. The hydraulic motor has an output shaft. The hydraulic pump supplies the hydraulic motor with hydraulic fluid via a working line. The hydraulic pump is driven by the electric motor. The components of the electro-hydraulic compact drive are located in a closed container filled with a hydraulic fluid. The container has an opening for coupling the output shaft of the hydraulic motor to the output element. The electro-hydraulic compact drive forms a closed unit that contains the complete electric motor/hydraulic pump/hydraulic motor arrangement. The compact drive combines the advantages of the high power density of hydraulics with a decentralized electric direct drive. The handling of the drive is simplified, thus also simplifying the control of underwater vehicles and machines.

Abstract: A rotary electrohydraulic actuator includes a direct drive hydraulic motor having an output shaft through opening that is concentric with a rotational axis of a rotor of the hydraulic motor. The actuator includes a power plant mounted on the hydraulic motor via a manifold. The power plant includes an electric motor driven hydraulic pump. Operation of the electric motor causes the hydraulic pump to supply pressurized fluid to the hydraulic motor. The power plant is compactly mounted to the manifold so that a longitudinal axis of the electric motor is parallel to and spaced apart from the rotational axis of the hydraulic motor.

Abstract: An electro-hydraulic compact drive for underwater use and for driving an output element includes a hydraulic motor, a hydraulic pump, and an electric motor as components of the electro-hydraulic compact drive. The hydraulic motor has an output shaft. The hydraulic pump supplies the hydraulic motor with hydraulic fluid via a working line. The hydraulic pump is driven by the electric motor. The components of the electro-hydraulic compact drive are located in a closed container filled with a hydraulic fluid. The container has an opening for coupling the output shaft of the hydraulic motor to the output element. The electro-hydraulic compact drive forms a closed unit that contains the complete electric motor/hydraulic pump/hydraulic motor arrangement. The compact drive combines the advantages of the high power density of hydraulics with a decentralized electric direct drive. The handling of the drive is simplified, thus also simplifying the control of underwater vehicles and machines.