A linear actuator system includes a linear actuator and an integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with two fluid drivers, each fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes the pump in a normal mode of operation in which the prime movers are independently driven and switches to a fail-safe mode of operation in which only one prime mover is operated.

A hydraulic system includes a hydraulic pump to be driven by a prime mover, a first hydraulic actuator, a second hydraulic actuator, a first connecting fluid tube connected to the first hydraulic actuator, a second coupling hydraulic tube connected to the first hydraulic actuator, and a first control valve having a first position and a second position. The hydraulic system includes a second control valve configured to control the second hydraulic actuator, a first fluid tube configured to supply a return fluid to the second control valve, a second fluid tube connected to the first fluid tube, a first communicating-connection tube to be connected to the second fluid tube when the first control valve is in the first position, and a second communicating-connection tube to be connected to the second fluid tube when the first control valve is in the second position.

A linear actuator system includes a linear actuator and at least one integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with at least one fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover to exclusively adjust at least one of a flow and a pressure in the linear actuator system to an operational set point.

A hydraulic drive system for an electrically-driven hydraulic work machine makes it possible to make a rated voltage of various electric equipment such as power storage devices common to one of an electrically-driven hydraulic work machine that is capable of being operated with lower horsepower and to prevent that only a power storage situation of one of the plurality of power storage devices significantly degrades together with operation of the electrically-driven hydraulic work machine and besides, to extend a time period within which each of actuators of the electrically-driven hydraulic work machine can obtain a predetermined speed. Accordingly, a controller 50 includes a virtual limitation torque calculation section 51 and electric motor rotational speed control sections 52 and 53. Variable horsepower control tables 52r and 53r are provided in the electric motor rotational speed control sections 52 and 53, and limit values q1*limit and q2*limit for a virtual displacement of the variable horsepower control tables 52r and 53r are changed such that a charge state of a power storage device 170 and a charge state of another power storage device 270 become equal to each other.

The present disclosure relates to a control device and a control method for a construction machine. The control device and the control method for the construction machine according to the exemplary embodiment of the present disclosure may adjust an engine revolutions per minute (rpm) according to a load applied to the construction machine, thereby controlling an output of equipment. In the control device and the control method for the construction machine according to the exemplary embodiment of the present disclosure, an output of a pump is increased at an appropriate time, so that good operation performance may be maintained, and in the case of an operation pattern, in which a load is low, the engine rpm is adjusted to be decreased, thereby improving fuel efficiency.

An electrohydraulic drive unit is provided, comprising a cylinder-piston assembly having a piston-side first hydraulic working chamber and a piston-rod-side second hydraulic working chamber, a tank, a hydraulic pump, which can be driven at variable rotational speed and which has a tank connection point and a working connection point, a valve assembly, which is connected between the working connection point of the hydraulic pump and the cylinder-piston assembly, and an anti-cavitation valve, which is connected between the tank and the first hydraulic working chamber; and a machine controller. Switching valves of the valve assembly can be switched between loading of the first hydraulic working chamber and loading of the second hydraulic working chamber of the cylinder-piston assembly during pumping operation of the hydraulic pump from the working connection point of the hydraulic pump by the machine controller.

A shovel according to an embodiment of the present invention includes a lower traveling body, an upper turning body pivotally mounted on the lower traveling body, a hydraulic pump mounted on the upper turning body, a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump, an operating device used to operate the actuator, and a control device configured to control an acceleration/deceleration characteristic of the hydraulic actuator in response to an operation of the operating device depending on a work mode.

A pressing tool is described for plastically deforming a workpiece. The pressing tool comprises a piston pump driven by a motor that rotates in operating rotation direction RA and a pressure release valve and a coupling arrangement, which mechanically couples the motor to the pressure relief valve, so that the motor opens the pressure relief valve when operated in a loosening rotation direction RL opposite to the operating rotation direction RA. Also described is a corresponding method of operating a pressing tool.

A hydraulic system includes a hydraulic pump to be driven by a prime mover, a first hydraulic actuator, a second hydraulic actuator, a first connecting fluid tube connected to the first hydraulic actuator, a second coupling hydraulic tube connected to the first hydraulic actuator, and a first control valve having a first position and a second position. The hydraulic system includes a second control valve configured to control the second hydraulic actuator, a first fluid tube configured to supply a return fluid to the second control valve, a second fluid tube connected to the first fluid tube, a first communicating-connection tube to be connected to the second fluid tube when the first control valve is in the first position, and a second communicating-connection tube to be connected to the second fluid tube when the first control valve is in the second position.

A linear actuator system includes a linear actuator and at least one integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with at least one fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover to exclusively adjust at least one of a flow and a pressure in the linear actuator system to an operational set point.