A hydraulic system includes: a cylinder that moves a moving object in a vertical direction by extension and retraction of a rod; a first bidirectional pump connected to a head-side chamber of the cylinder by a first supply/discharge line; a second bidirectional pump connected to a rod-side chamber of the cylinder by a second supply/discharge line and coupled to the first bidirectional pump in a manner enabling torque to be transmitted between the first and second bidirectional pumps; a relay line connecting the first and second bidirectional pumps such that a hydraulic liquid discharged from one of the first and second bidirectional pumps is introduced into the other of the first and second bidirectional pumps; and a servomotor that drives the first or second bidirectional pump. At least one of the first and second bidirectional pumps is a variable displacement pump whose delivery capacity per rotation is freely variable.

The disclosure relates to a hydraulic control block for controlling a pressure medium supply of a hydraulic cylinder of a hydraulic spindle. The hydraulic control block includes a generic hydraulic switching structure electively configurable in each of a plurality of specific hydraulic switching structures, each of the plurality of specific hydraulic switching structures having a respective hydraulic cylinder with a number of piston areas which differs from a number of piston areas in the respective hydraulic cylinders of each of the other of the plurality of specific hydraulic switching structures.

A portable hydraulic power unit includes a frame, a fluid tank supported by the frame, and a manifold supported by the frame. The fluid tank is configured to store a supply of hydraulic fluid for powering a hydraulically-driven tool. A reciprocating pump is mounted on the exterior of the fluid tank and on the exterior of the manifold. The reciprocating pump is secured to the fluid tank and the manifold with fasteners extending through a cylinder body of the reciprocating pump.

A hydraulic control loop controls a hydraulic adjusting cylinder. The cylinder has a cylindrical housing and a displaceable piston therein. The piston divides the housing interior into a first and a second hydraulic chamber. A first hydraulic valve supplies the first hydraulic chamber with hydraulic fluid. A hydraulic pressure of the first hydraulic chamber is adjustable by controlling the first hydraulic valve. A second hydraulic valve supplies the second hydraulic chamber with hydraulic fluid. A hydraulic pressure of the second hydraulic chamber is adjustable by controlling the second hydraulic valve. A control device controls the two hydraulic valves. In a position control state, the second hydraulic valve is controlled by a position control signal dependent on the working position of the piston and the first hydraulic valve is controlled by an adjusted position control signal, that is generated on the basis of the position control signal.

A sheet metal working machine includes a hydraulic drive system to drive a plurality of working tools in a separate and independent manner. The hydraulic drive system includes a plurality of hydraulic cylinders provided with pistons defining thrust chambers and return chambers and associated with corresponding working tools, a reversible first pump connected to the thrust chambers and arranged to send fluid to, or to suck fluid from, at least one of the thrust chambers so as to move the respective piston and the working tool associated therewith, a plurality of valves interposed between the first pump and the thrust chambers of the respective hydraulic cylinders and activable to connect the first pump to the thrust chambers; a hydraulic accumulator connected to the return chambers and arranged for maintaining fluid at a defined preload pressure therein.

A hydraulic control loop controls a hydraulic adjusting cylinder. The cylinder has a cylindrical housing and a displaceable piston therein. The piston divides the housing interior into a first and a second hydraulic chamber. A first hydraulic valve supplies the first hydraulic chamber with hydraulic fluid. A hydraulic pressure of the first hydraulic chamber is adjustable by controlling the first hydraulic valve. A second hydraulic valve supplies the second hydraulic chamber with hydraulic fluid. A hydraulic pressure of the second hydraulic chamber is adjustable by controlling the second hydraulic valve. A control device controls the two hydraulic valves. In a position control state, the second hydraulic valve is controlled by a position control signal dependent on the working position of the piston and the first hydraulic valve is controlled by an adjusted position control signal, that is generated on the basis of the position control signal.

A fluid pressure cylinder includes a first cylinder portion and a second cylinder portion disposed in parallel, and a supply-and-discharge port. The first cylinder portion is partitioned by a first piston into a head-side first accumulation chamber and a rod-side second accumulation chamber. The second cylinder portion is partitioned by a second piston into a head-side release chamber and a rod-side drive chamber. Pressurized fluid is supplied to and discharged from the second accumulation chamber and the drive chamber through the supply-and-discharge port. An end of a first piston rod connected to the first piston and an end of a second piston rod connected to the second piston are connected to each other. The first piston includes a communication switching valve switching communication between the first accumulation chamber and the second accumulation chamber, between enabled and disabled.

A hydraulic control circuit operable to selectively hydraulically link first and second hydraulic actuators and to bypass that hydraulic link.

A pressure-measuring system, including a tube system having at least first and second pressure measuring devices, each including a pressure transducer membrane and a measuring chamber. A first flow regulation device with a perfusion tube section is positioned between the first pressure measuring device and a supply of fluid, and has a first tube clamp that acts on a tube section by squeezing. The system further includes at least one non-perfusion regulation device.

A hydromechanical linear converter has a cylinder, a piston unit and a seat valve unit. The cylinder and a piston of the piston unit delimit a hydraulic working chamber, into which a working connection and a further fluid connection open, and has a supply connection 10. The valve unit switches between a first position connecting the supply connection to the fluid connection and a second position blocking the fluid connection from the supply connection. The linear converter includes a valve housing with a valve seat 16, a valve body with a valve head cooperating with the seat, a spring unit preloading the valve body into a position corresponding to the first position and an electromagnetic actuator 14 acting on the valve body 12 by purely mechanical action, to move the valve body against the force of the spring unit into a position corresponding to the second switching position.