An interlocked single function activation valve for hydraulic systems is disclosed. The hydraulic valve prevents unsafe tie-down or safety override situations by requiring the safety mechanism to be reset each time the hydraulic system is used. The hydraulic valve includes an interlock spool that moves to an extension position when the hydraulic system is de-pressurized and then re-pressurized while the control lever is engaged (i.e., tied down). When the interlock spool is in the extension position, it prevents the system from reaching a working pressure, thereby forcing a reset of the control lever before the system can reach working pressure.

An interlocked single function activation valve for hydraulic systems is disclosed. The hydraulic valve prevents unsafe tie-down or safety override situations by requiring the safety mechanism to be reset each time the hydraulic system is used. The hydraulic valve includes an interlock spool that moves to an extension position when the hydraulic system is de-pressurized and then re-pressurized while the control lever is engaged (i.e., tied down). When the interlock spool is in the extension position, it prevents the system from reaching a working pressure, thereby forcing a reset of the control lever before the system can reach working pressure.

A method is for testing a hydraulic system (1), having a pump (2) which, in a first direction of rotation (3), conveys fluid to a first consumer (4) for a volume flow function and, in a second direction of rotation (5), conveys fluid to at least one second consumer (6) for an actuation function. The method includes testing hydraulic readiness of the hydraulic system (1); drawing fluid into the hydraulic system (1); ventilating the hydraulic system (1). A hydraulic system (1) carries out such a method, having a pump (2) which can be driven in a first direction of rotation (3) for a volume flow function and can be driven in a second direction of rotation (5) for an actuation function.

Provided is a hydraulic drive apparatus of a work machine capable of reducing a surge pressure. The hydraulic drive apparatus includes a control valve interposed between the hydraulic pump and a hydraulic actuator, an operation device moving the control valve in response to an actuator operation, an unload valve, an unload operation valve changing a pilot pressure of the unload valve in response to an input of an unload operation command, a target pressure calculation part, and an unload operation command part. The target pressure calculation part calculates a target pressure that increases with an increase in the holding pressure of the hydraulic actuator. The unload operation command part inputs an unload operation command to the unload operation valve to make the pump pressure of the hydraulic pump follow the target pressure.

The self-contained energy efficient hydraulic actuator system of the present invention includes a hydraulic cylinder, a servo motor that is configured to produce rated torque from zero RPM to maximum rated RPM with rotor speed/position feedback to a servo motor, a pump, and a solenoid valve that enables the hydraulic cylinder to maintain its position without the motor running. The system has the ability to hold a load in place without motor operation via the use of the solenoid valve, and therefore saves energy and extends the motor lifetime by minimizing the motor running time.

A controller unit is included in a liquid-pressure driving system for use in a working machine configured to supply an operating liquid to an actuator to move a structural body by the actuator. The controller unit includes: a gyro sensor configured to output a signal corresponding to an operation velocity of the structural body; and a controller configured to control a flow rate of the operating liquid supplied to the actuator, based on the signal output from the gyro sensor and corresponding to the operation velocity of the structural body, wherein: the controller is attached to the structural body; and the gyro sensor is incorporated in the controller.

A crane hydraulic system and a controlling method of the system is provided in order to fundamentally reduce impact in start and stop operations of a load sensing winch system. The load sensing subsystem is arranged, at the start and stop moments of a winch system, the pressure compensator can be opened, and the variable pump oil inlet line communicates with the oil return line to realize pressure relief, so as to reduce the pressure impact.

In accordance with an example embodiment, a hydraulic system may include a pump, reservoir, accumulator, hydraulic cylinder, ride control valve assembly, and controller. The ride control valve assembly may include a charging valve, discharging valve, and a head ride control valve. The controller may open the head ride control valve when a ride control feature has been activated, or open the charging valve if the ride control feature has not been activated and a hydraulic fluid warmup is to be performed.

A pressure booster includes a pressure boosting unit and a bypass unit. The pressure boosting unit includes an input port connected to the side of a fluid supply source and an output port connected to the side of a tank. The pressure boosting unit boosts the pressure of a pressurized fluid supplied to the input port and outputs the pressure-boosted pressurized fluid from the output port. The bypass unit includes a bypass flow path having one end connected to the fluid supply source side and the other end connected to the output port side. The bypass flow path is provided with a bypass check valve configured to block the flow of the pressurized fluid from the output port side to the fluid supply source side.

Disclosed are a slit valve apparatus and a method for controlling a slit valve. The slit valve apparatus includes a slit valve assembly and a servo-control system in communication with the slit valve assembly. The slit valve assembly includes at least one gate able to transition between an open position and a closed position, at least one pneumatic actuator, at least one proportional pneumatic valve including a plurality of controllers, and a continuous position sensor. The servo-control system includes a centralized controller that generates a control signal and adjusts the movement of the at least one gate based on the position trajectory for the gate, a linear position measurement of the gate from the continuous position sensor, and fluid pressure/flow measurements from the plurality of controllers.