Provided is a swing-back preventing apparatus capable of preventing a hydraulic actuator in a stop state from operating by undesired load. The swing-back preventing apparatus includes a housing, a piston, and a pair of biasing members. First and second spaces are formed between the piston and the housing, and the piston includes a pair of communication passages that are communicable with first and second spaces. When the piston is located at a first offset position, the first space is blocked from a first port. When the piston separates from the first offset position, the first space is connected to the first port. When the piston is located at a second offset position, the second space is blocked from a second port. When the piston separates from the second offset position, the second space is connected to the second port. When the piston is located at a position on the first offset position side of a neutral position, a first communication passage is connected to the first space. When the piston is located in a range from the neutral position to the second offset position, the first communication passage is blocked from the first space. When the piston is located at a position on the second offset position side of the neutral position, a second communication passage is connected to the second space. When the piston is located in a range from the neutral position to the first offset position, the second communication passage is blocked from the second space.

A fluid valve has a valve plug configured as follows. In order to control a flow rate of a fluid between a first pressure chamber and a second pressure chamber, the valve plug is provided so as to be openable and closable in accordance with a difference between forces generated by pressures in the pressure chambers and resilience of an elastic member. The fluid valve includes an opening motion promoting portion. The opening motion promoting portion promotes an increase in degree of opening of the valve plug after the valve plug has been opened.

A hydraulic circuit having a function of compensation and energy recovery comprises a distribution module, a three-way compensated regulator device, a variable flow rate or pressure feeding assembly, an energy recovery device connected to the three-way compensated regulator device. The distribution module comprises a spool including an inlet recess and a drain recess configured so that the flow rate of fluid inlet to the utility is equal to or less than the one outlet therefrom, possibly net of a correction factor. There is also a respective first driving channel and a second driving channel configured so that a pressure taken upstream of the drain recess acts on a first side of the regulator device, and so that a pressure taken downstream of the drain recess in the first channel acts on a second side of the regulator device, and an additional force.

A work machine includes an electric drive system. The work machine includes a prime mover, a machine controller, and a hydraulic control system. The hydraulic control system includes a pump, a control valve and a retarding control valve. The pump is configured to supply pressurized fluid to the hydraulic control system via a supply line. The control valve is fluidly coupled to the pump via the supply line, and includes a pressure relief valve. The retarding control valve is fluidly connected to the pump and the control valve. The retarding control valve includes a solenoid valve, an orifice and a check valve. The solenoid valve is coupled to the machine controller, the orifice restricts a flow of the pressurized fluid through the supply line, and the check valve is coupled to a discharge line, which branches from a point along the supply line between the solenoid valve and the orifice.

A fluid system with a safety-oriented valve assembly including a first fluid connection for a fluidic connection with a fluid connection of a fluid source or a control valve and a second fluid connection for coupling a fluid load as well as a fluid channel between the fluid connections, wherein a first valve can be actuated between a fluid supply position, or open position, and a fluid discharge position, or closed position, is arranged in the fluid channel, wherein a second valve which can be adjusted between an open position for the fluid channel and a throttle position for the fluid channel is arranged in the fluid channel and wherein a sensor for detecting a fluid pressure and for outputting a fluid pressure-dependent sensor signal is arranged in a section of the fluid channel between the first valve and the second valve and including a controller which is designed to process the sensor signal and to process control signals for the valve.

A system for recovering energy from a hydraulic actuator and to a method of operating the system are described. The system may have a hydraulic actuator and a source of hydraulic pressure, comprising a hydraulic pump, in fluid communication with the hydraulic actuator for pressurizing the hydraulic actuator. The system may also have a hydraulic accumulator assembly for selectively absorbing energy from the hydraulic actuator or via the hydraulic actuator. The system may also have a first one-way valve configured to provide fluid communication between the hydraulic actuator and the hydraulic accumulator assembly. The first one-way valve may be configured to permit a flow of fluid through the first one-way valve from the hydraulic actuator to the hydraulic accumulator assembly. The first one-way valve may also be configured to block a flow of fluid through the first one-way valve from the hydraulic accumulator assembly to the hydraulic actuator.

A valve, in particular for use as a pressure maintenance-type component (38) in hydraulically actuated hoisting devices (2), having a valve housing (54), which has a control port (40) plus a fluid inlet (64) and a fluid outlet (66), and having a regulating piston (68) longitudinally displaceably arranged in the valve housing (54), which regulating piston, against the action of an energy storage device (70), in particular in the form of a compression spring, brings the regulating piston (68) into at least one position forming a fluid-conveying connection between the fluid inlet (40) and the fluid outlet (66) or blocks this connection by means of a control pressure existing at the control port (40), is characterized in that a first diaphragm (88) is arranged in the regulating piston (68), which connects the control port (40) to a receiving space (62) for the energy storage device (70) in a fluid-conveying manner, and in that a second diaphragm (90) is arranged in an intermediate part (72) in the valve housing (54), by means of which the receiving space (62) can be connected to a compensating chamber (92), which connected to the fluid outlet (66) in a fluid-conveying manner (98).

A hydraulic system includes a supply line, at least one implement-based control valve, an implement-based pressure regulating valve, and a load sensing circuit. The implement-based control valve(s) is fluidly coupled to the supply line and configured to regulate a flow of the pressurized hydraulic fluid supplied through at least one downstream actuator line to at least one hydraulic actuator of the implement. The implement-based pressure regulating valve is fluidly coupled to the supply line upstream of the control valve(s) and configured to regulate a fluid pressure to be equal to or greater than a minimum fluid pressure. The load sensing circuit is fluidly coupled to the pressure regulating valve and provides a line or load pressure to the pressure regulating valve. The pressure regulating valve is configured to regulate the supply of the pressurized hydraulic fluid based on the line pressure.

Provided is a swing-back preventing apparatus capable of preventing a hydraulic actuator in a stop state from operating by undesired load. The swing-back preventing apparatus includes a housing, a piston, and a pair of biasing members. First and second spaces are formed between the piston and the housing, and the piston includes a pair of communication passages that are communicable with first and second spaces. When the piston is located at a first offset position, the first space is blocked from a first port. When the piston separates from the first offset position, the first space is connected to the first port. When the piston is located at a second offset position, the second space is blocked from a second port. When the piston separates from the second offset position, the second space is connected to the second port. When the piston is located at a position on the first offset position side of a neutral position, a first communication passage is connected to the first space. When the piston is located in a range from the neutral position to the second offset position, the first communication passage is blocked from the first space. When the piston is located at a position on the second offset position side of the neutral position, a second communication passage is connected to the second space. When the piston is located in a range from the neutral position to the first offset position, the second communication passage is blocked from the second space.

A hydraulic elevator may comprise a bidirectional pump that controls up and down motion of an elevator car. A VVVF drive may cause the bidirectional pump to provide working fluid in a controlled manner to a hydraulic jack that supports the elevator car. A control valve may be disposed between the bidirectional pump and the hydraulic jack so that the control valve can be closed when the elevator car needs to be held in place. To avoid pressure waves that propagate when the control valve is opened with disparate pressures on the pump and jack sides of the control valve, the bidirectional pump may adjust the pressure on the pump side of the closed control valve to the pressure on the jack side of the control valve before the control valve is opened.