The object is to make it possible to efficiently utilize rated output torque of the prime mover by performing total torque control with high precision through precise detection of absorption torque of the other hydraulic pump by use of a purely hydraulic structure and feedback of the absorption torque to the one hydraulic pump's side. For this purpose, the hydraulic drive system is equipped with: a torque feedback circuit 112v which is supplied with delivery pressure of a main pump 202 and load sensing drive pressure, modifies the delivery pressure of the main pump 202 to achieve a characteristic simulating the absorption torque of the main pump 202, and outputs the modified pressure; and a torque feedback piston 112f which is supplied with output pressure of the torque feedback circuit and controls displacement of a main pump 102 so as to decrease the displacement of the main pump 102 and thereby decrease maximum torque T12max as the output pressure increases. The torque feedback circuit 112v includes first and second variable pressure reducing valves 112g and 112q.

A patient support apparatus includes a base, a litter frame, and an elevation assembly supporting the litter frame on the base. The elevation assembly is configured to effect changes in elevation of the litter frame relative to the base. The elevation assembly includes a pair of hydraulic actuators and a hydraulic fluid control system for delivering fluid to the first and second hydraulic actuators. The control system includes a pump and a user operable control coupled to the pump for controlling the flow of hydraulic fluid from the pump to the first and second hydraulic actuators.

Disclosed is a turbine fracturing apparatus. The turbine fracturing apparatus includes: a main power assembly and an auxiliary power assembly. The main power assembly includes a first power source and a piston pump connected to the first power source; the first power source outputs power to the piston pump, and the piston pump outputs a first liquid. The auxiliary power assembly includes a second power source, a load sensitive system connected to the second power source, and an auxiliary power device; the second power source outputs power to the load sensitive system, the load sensitive system is connected to the auxiliary power device and outputs a second liquid for the auxiliary power device. The first liquid is different from the second liquid, and the first liquid and the second liquid have certain pressure. The load sensitive system is configured to regulate a pressure of the second liquid in real time according to pressure of the second liquid required by the auxiliary power device.

A hydraulic tool including a tank, which is filled with oil, a hand pump connected to the tank in fluid communication, having a spring-loaded lever mechanism, which is in operative connection with a pump piston, with a piston cylinder system as actuator, which is connected to the pump in fluid communication with a non-return valve, wherein the piston surface of the actuator is a multiple of the piston surface of the hand pump.

A control system of a hybrid construction machine includes a regeneration passage switching valve having a normal position where flow of working fluid is blocked, and a regeneration position allowing for the working fluid to flow from main passages to a regeneration motor when a working fluid pressure of the main passages reaches a set pressure during operation of the actuators, and an assist switching valve having a normal position proportionally dividing the working fluid of an assist passage into a regeneration passages, a first switching position supplying more working fluid of the assist passage to one of the main passages when that the one has a higher working fluid pressure, and a second switching position supplying more working fluid of the assist passage to the other one of the main passages when that the other one has a higher working fluid pressure.

The invention relates to an actuator device, having two working chambers which are coupled to one another in such a way that a volume increase in a first of the working chambers is associated with a volume decrease in the second working chamber, and vice versa. There is provided an output device which can be driven, and thus moved, by the respective volume increase in the respective working chamber. There is provided a pump device having a solid-state actuator and intended for conveying a fluid. There is provided a first flow path through which the fluid conveyed by means of the pump device can flow and via which, to bring about the volume increase in the first working chamber, the fluid conveyed by means of the pump device and flowing through the first flow path can be introduced into the first working chamber.

A hydraulic fluid energy regeneration apparatus of a work machine includes: a regeneration hydraulic motor driven by a return hydraulic fluid; a first hydraulic pump mechanically connected to the regeneration hydraulic motor; a second hydraulic pump that delivers a hydraulic fluid for driving a hydraulic actuator; a confluence line that causes the hydraulic fluid delivered from the first hydraulic pump to join the hydraulic fluid delivered from the second hydraulic pump; a first adjuster configured to adjust the flow rate of the hydraulic fluid of the first hydraulic pump; and a second adjuster configured to adjust the delivery flow rate of the second hydraulic pump. A control device includes: a first calculation section configured to calculate a non-confluence time pump flow rate in the case where the hydraulic actuator is driven solely by the second hydraulic pump and calculate a control command output to the first adjuster such that the flow rate of the hydraulic fluid from the first hydraulic pump is equal to or lower than the non-confluence time pump flow rate; and a second calculation section configured to calculate a target pump flow rate by subtracting from the non-confluence time pump flow rate the flow rate of the hydraulic fluid from the first hydraulic pump and calculate a control command output to the second adjuster such that the target pump flow rate is attained.

A control system for hybrid construction machine includes: an operation valve for operating a boom; a variable displacement type fluid pressure motor; a distribution mechanism adapted to adjust a flow to be distributed to the fluid pressure motor; a motor generator adapted to be rotated integrally with the fluid pressure motor; a variable displacement type assist pump adapted to be rotated integrally with the motor generator; a distribution mechanism control unit adapted to control the distribution mechanism; a tilt angle control unit adapted to control tilt angles of the fluid pressure motor and the assist pump; and a motor generator control unit adapted to maintain a rotation speed of the motor generator at a target rotation speed. The target rotation speed at the time of boom regeneration control is set to higher than the target rotation speed in a case where only an assist control is carried out.

A hydraulic control system for a machine is provided. The hydraulic control system includes a fluid reservoir and a pump motor. The pump motor is fluidly coupled to the fluid reservoir. The pump motor is configured to provide pressurized fluid and to receive fluid to provide a power output to the shaft. The hydraulic control system further includes an actuator and an accumulator fluidly coupled to the pump motor and the actuator. The hydraulic control system further includes an accumulator valve and a controller. The accumulator valve is fluidly coupled between the accumulator and the pump motor. The controller is in communication with the pump motor and the accumulator valve. The controller is configured to detect an operator command to operate the power source; determine pressure at the accumulator; and selectively move the accumulator valve to fluidly connect the accumulator with the pump motor.

A hydraulic drive device for a molding machine includes at least one motor, such as an electric motor, at least one first hydraulic pump which can be driven by the at least one motor, and at least one flywheel. At least one second hydraulic pump is connected, or can be connected, with the at least one flywheel, and a hydraulic connection conduct is provided between the first hydraulic pump and the second hydraulic pump.