A hydraulic system includes a first and a second rotating hydraulic machine, the first and second hydraulic machine being arranged to provide a torque via a common output shaft; a first valve arrangement for providing a differential hydraulic pressure level over the first hydraulic machine by using two sources of hydraulic fluid having different hydraulic pressure levels, a second valve arrangement for providing a differential hydraulic pressure level over the second hydraulic machine by using two sources of hydraulic fluid having different hydraulic pressure levels; and a control unit configured to control the first valve arrangement and the second valve arrangement such that different discrete levels of torque are provided via the output shaft of the hydraulic system. A hydraulic system for providing different discrete levels of torque using one hydraulic machine and a plurality of differential pressure levels, and a method for controlling a hydraulic system, are also provided.

A hydraulic system includes a first and a second rotating hydraulic machine, the first and second hydraulic machine being arranged to provide a torque via a common output shaft; a first valve arrangement for providing a differential hydraulic pressure level over the first hydraulic machine by using two sources of hydraulic fluid having different hydraulic pressure levels, a second valve arrangement for providing a differential hydraulic pressure level over the second hydraulic machine by using two sources of hydraulic fluid having different hydraulic pressure levels; and a control unit configured to control the first valve arrangement and the second valve arrangement such that different discrete levels of torque are provided via the output shaft of the hydraulic system. A hydraulic system for providing different discrete levels of torque using one hydraulic machine and a plurality of differential pressure levels, and a method for controlling a hydraulic system, are also provided.

An electric fluid pressure cylinder is provided with: a driving unit integrally provided with an electric motor, a pump configured to discharge working oil by being driven by the electric motor, and a tank; a hydraulic cylinder configured to be extended and contracted by the working oil supplied from the driving unit; and a first hose pipe and a second hose pipe configured to guide the working oil between the driving unit and the hydraulic cylinder. The driving unit is further provided with: a valve block configured to control the flow of working fluid between the fluid pressure cylinder and the pump; and a connecting plate attached to the valve block and formed with a connecting port to which the pipe member is connected, the connecting port being configured such that the working fluid supplied to and discharged from the fluid pressure cylinder passes through the connecting port.

An electric fluid pressure cylinder is provided with: a driving unit integrally provided with an electric motor, a pump configured to discharge working oil by being driven by the electric motor, and a tank; a hydraulic cylinder configured to be extended and contracted by the working oil supplied from the driving unit; and a first hose pipe and a second hose pipe configured to guide the working oil between the driving unit and the hydraulic cylinder. The driving unit is further provided with: a valve block configured to control the flow of working fluid between the fluid pressure cylinder and the pump; and a connecting plate attached to the valve block and formed with a connecting port to which the pipe member is connected, the connecting port being configured such that the working fluid supplied to and discharged from the fluid pressure cylinder passes through the connecting port.

An example tool includes a hydraulic actuator cylinder; a piston slidably accommodated within the hydraulic actuator cylinder, where the piston includes a piston head and a piston rod extending from the piston head along a central axis direction of the hydraulic actuator cylinder, the piston head divides an inside of the hydraulic actuator cylinder into a first chamber and a second chamber, and the piston rod is disposed in the first chamber and configured to move one or more jaws of the tool; a pump configured to provide pressurized fluid; and a sequence valve configured to block the pressurized fluid from flowing into the second chamber of the hydraulic actuator cylinder until pressure of the pressurized fluid exceeds a threshold pressure value.

An example tool includes a hydraulic actuator cylinder; a piston slidably accommodated within the hydraulic actuator cylinder, where the piston includes a piston head and a piston rod extending from the piston head along a central axis direction of the hydraulic actuator cylinder, the piston head divides an inside of the hydraulic actuator cylinder into a first chamber and a second chamber, and the piston rod is disposed in the first chamber and configured to move one or more jaws of the tool; a pump configured to provide pressurized fluid; and a sequence valve configured to block the pressurized fluid from flowing into the second chamber of the hydraulic actuator cylinder until pressure of the pressurized fluid exceeds a threshold pressure value.

The invention relates to a hydraulic device for driving an actuator to be hydraulically controlled or actuated, comprising a motor arranged in a motor housing, a compensating tank (31) for accommodating hydraulic fluid, and a hydraulic pump, which is arranged in a pump housing and driven by the motor, wherein the hydraulic pump is designed in such a way that the hydraulic pump permits conveyance of hydraulic fluid in two directions, namely in the forward direction and in the backward direction, wherein the hydraulic actuator comprises a drive cylinder, which has a first and a second cylinder chamber and a drive piston (3) arranged therebetween, to which drive piston a drive shaft (2) that can be displaced in the longitudinal direction is attached, wherein the device comprises a loading cylinder for an emergency closing spring (16), in which loading cylinder a loading cylinder chamber (12) and a loading piston (11) that can be coupled to the drive shaft (2) are arranged, wherein the emergency closing spring (16) can be loaded into a loaded or emergency-triggering readiness position by the loading piston (11), wherein the loading cylinder chamber (12) is connected to an outlet of the hydraulic pump in such a way that the loading cylinder chamber (12) can be filled with hydraulic fluid by means of the hydraulic pressure of the hydraulic pump and the loading piston can be transferred into a loading position as the emergency closing spring (16) is compressed and the loading piston can be locked there hydraulically by means of check valves (36, 37), and wherein a controlled seat valve (50) is connected to an inflow/outflow opening of the loading cylinder chamber, by means of which seat valve the emergency closing spring (16) can be transferred from the loaded readiness position into an emergency-triggering opening position, wherein both the hydraulic fluid that is contained in the loading cylinder chamber (12) and holds the emergency closing spring (16) in the readiness position and the hydraulic fluid contained in the first cylinder chamber can be discharged via the controlled seat valve (50).

The invention relates to a hydraulic device for driving an actuator to be hydraulically controlled or actuated, comprising a motor arranged in a motor housing, a compensating tank (31) for accommodating hydraulic fluid, and a hydraulic pump, which is arranged in a pump housing and driven by the motor, wherein the hydraulic pump is designed in such a way that the hydraulic pump permits conveyance of hydraulic fluid in two directions, namely in the forward direction and in the backward direction, wherein the hydraulic actuator comprises a drive cylinder, which has a first and a second cylinder chamber and a drive piston (3) arranged therebetween, to which drive piston a drive shaft (2) that can be displaced in the longitudinal direction is attached, wherein the device comprises a loading cylinder for an emergency closing spring (16), in which loading cylinder a loading cylinder chamber (12) and a loading piston (11) that can be coupled to the drive shaft (2) are arranged, wherein the emergency closing spring (16) can be loaded into a loaded or emergency-triggering readiness position by the loading piston (11), wherein the loading cylinder chamber (12) is connected to an outlet of the hydraulic pump in such a way that the loading cylinder chamber (12) can be filled with hydraulic fluid by means of the hydraulic pressure of the hydraulic pump and the loading piston can be transferred into a loading position as the emergency closing spring (16) is compressed and the loading piston can be locked there hydraulically by means of check valves (36, 37), and wherein a controlled seat valve (50) is connected to an inflow/outflow opening of the loading cylinder chamber, by means of which seat valve the emergency closing spring (16) can be transferred from the loaded readiness position into an emergency-triggering opening position, wherein both the hydraulic fluid that is contained in the loading cylinder chamber (12) and holds the emergency closing spring (16) in the readiness position and the hydraulic fluid contained in the first cylinder chamber can be discharged via the controlled seat valve (50).

An arrangement for manipulating the flow of a fluid into a fluid actuator, preferably of a seat, has a base body having an opening designed to introduce the fluid into the base body, and at least one further opening provided for forwarding or discharging the fluid introduced into the base body. Means for producing and/or interrupting a fluid-conducting connection between the openings are provided. The means comprise such additional means that can be charged with a pressure of the fluid to be conducted and are designed such that, in a first pressure range of the fluid, the fluid entering the base body from the fluid actuator is discharged via one of the openings from the base body to the surroundings and, in a second pressure range of the fluid that is higher than the first pressure range, the fluid introduced into the base body is introduced into the fluid actuator.

An arrangement for manipulating the flow of a fluid into a fluid actuator, preferably of a seat, has a base body having an opening designed to introduce the fluid into the base body, and at least one further opening provided for forwarding or discharging the fluid introduced into the base body. Means for producing and/or interrupting a fluid-conducting connection between the openings are provided. The means comprise such additional means that can be charged with a pressure of the fluid to be conducted and are designed such that, in a first pressure range of the fluid, the fluid entering the base body from the fluid actuator is discharged via one of the openings from the base body to the surroundings and, in a second pressure range of the fluid that is higher than the first pressure range, the fluid introduced into the base body is introduced into the fluid actuator.