A piston accommodated in an internal space of a cylinder and forming a pair of pressure chambers together with the cylinder, the piston being configured to move relative to the cylinder; a first actuator connected to one pair of pressure chambers; a second actuator connected to the other of the pair of pressure chambers; a position detector configured to detect a position of the piston relative to the cylinder; a pressure detector configured to detect a pressure of one pair of pressure chambers; and a controller configured to control the first actuator and the second actuator. The controller controls one of the first actuator and the second actuator that the position detected by the position detector is made close to a target position and controls the other of the first actuator and the second actuator that the pressure detected by the pressure detector is made close to a target pressure.

A volumetric compensator assembly for use in the seal section of a pumping system includes an envelope bladder that in turn includes a flexible top sheet and a bottom sheet connected to the top sheet along a pair of side seams and an end seam. The top sheet and bottom sheet together define a bladder interior that has a variable capacity. The volumetric compensator assembly also has a bladder support tube and the envelope bladder is coiled around the bag support tube.

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.

Pump-controlled hydraulic circuits are more efficient than valve-controlled circuits, as they eliminate the energy losses due to flow throttling in valves and require less cooling effort. Presently existing pump-controlled solutions for single rod cylinders encounter an undesirable performance during certain operating conditions. Novel circuit designs employ use of different charge pressures on a pair of pilot-operated charging-control valves or different piston areas and/or spring constants on a shuttle-type charging control valve to shift a critical loading region in a load-force/actuator-velocity plane to a lower load force range, thereby reducing the undesired oscillations experienced in the response of the typical critical loading region. One or more specialized valves are controlled by fluid pressures to provide throttling in the circuit only within the critical loading region, thereby reducing the oscillatory amplitude while avoiding throttling-based energy losses outside the critical region over the majority of the circuit's operational overall operating area.

Provided is a hydraulic drive device that is provided in a work device and with which it is possible to obtain a high energy-saving effect with a low-cost configuration while being equipped with a plurality of hydraulic actuators. The hydraulic drive device is provided with: first and second actuator groups; closed circuits connected to hydraulic actuators included in the first actuator group; a pump section including closed circuit pumps; open circuits which include a plurality of variable throttle valves for changing the flow rate of working fluid supplied from a hydraulic pump included in the pump section to a hydraulic actuator; and circuit switching sections having a first state in which the closed circuits are opened and the opened circuits are blocked, and a second state in which the closed circuits are blocked and the open circuits are opened.

A method and apparatus for reducing a positive pressure of an actuating cylinder of a universal hinged support. An application object is the actuating cylinder of the universal hinged support. The apparatus comprises a foundation, a base frame, a force application apparatus, a direction adaptation apparatus, a universal swing rod apparatus, and an integral external connection apparatus. The method comprises: step 1, determining main design parameters and the type of the force application apparatus; step 2, structural design of the apparatus: designing the structure of the apparatus after the main design parameters and the type of the force application apparatus are determined; and step 3, calculating, testing, and evaluating an actual gravity moment or positive pressure and an effect of weight compensation, determining whether to meet design requirements, and calculating or testing the evaluated gravity moment and a reduction ratio.

A method and apparatus for reducing a positive pressure of an actuating cylinder of a universal hinged support. An application object is the actuating cylinder of the universal hinged support. The apparatus comprises a foundation, a base frame, a force application apparatus, a direction adaptation apparatus, a universal swing rod apparatus, and an integral external connection apparatus. The method comprises: step 1, determining main design parameters and the type of the force application apparatus; step 2, structural design of the apparatus: designing the structure of the apparatus after the main design parameters and the type of the force application apparatus are determined; and step 3, calculating, testing, and evaluating an actual gravity moment or positive pressure and an effect of weight compensation, determining whether to meet design requirements, and calculating or testing the evaluated gravity moment and a reduction ratio.

A rotating pumping apparatus is provided which may be employed in an automotive brake system. The rotating pumping apparatus includes a sealing member and a pressure member. The sealing member is disposed around a pump drive shaft. The pressure member includes a plate spring, a first rotation stopper, and a second rotation stopper. The first rotation stopper serves to stop the pressure member from rotating following rotation of the pump drive shaft. The second rotation stopper engages the seal ring to stop the sealing member from rotating following the rotation of the pump drive shaft. The plate spring works to elastically press the sealing member against a stopper wall of a pump casing to stop the sealing member from moving in an axial direction of the pump drive shaft.

A master cylinder for a regulated braking system having at least one piston, which is movable in a housing and which is sealed from a pressure chamber by a sealing element arranged in a ring groove of the housing, which can be connected to an unpressurized supply chamber by control passages designed in the pistons. In order to reduce the flow resistance of the control passages at the same dead stroke, the control passages have a control edge designed parallel to a piston end face of at least one of the pistons.

Systems, methods and devices are described providing a selective hydraulic or electrically powered prime mover that is a (bi-directional power unit) PU system, including movement within a device or system used to compress and/or expand a fluid and provide fluid movement within the same device or system. The use of a (hydraulic power unit) HPU is involved and comprises at least a pump or other hydraulic fluid moving device often referred to as a prime mover, one or more first set of selective control valves delivering pressurized fluid to the device(s), and one or more second set of selective control valves returning unpressurized fluid from the device(s), a reservoir comprising a compensator tank, a port allowing for operation at ambient pressure, and a pressure measuring device measuring ambient pressure allowing for unbalanced flow to and from the mechanical (user) device as well as thermal expansion or compression.