A hydraulic thruster system for providing an axial force. In one embodiment, the system comprises a pump, a motor for driving the pump, and a hydraulic thruster comprising: a cylinder comprising a plurality of cylinder pistons; a shaft comprising a plurality of shaft pistons; a plurality of first pressure chambers; and a plurality of second pressure chambers, wherein the plurality of shaft pistons are positioned inside the cylinder, between the cylinder pistons to form the plurality of first and a second pressure chambers, wherein the shaft further comprises a first fluid passage connected to the pump and to the first pressure chambers, and a second fluid passage connected to the pump and to the second pressure chambers, and wherein the pump may pump fluid into the first pressure chambers and suction fluid from the second pressure chambers providing an axial force between the shaft and the cylinder.

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 hydraulic system, for use under water with a hydraulic actuating drive, includes a hydraulic cylinder and at least one hydraulic machine. At least one rotary drive device and the hydraulic machine are coupled mechanically for a common rotating movement, and the hydraulic machine adjusts at least the hydraulic cylinder. The hydraulic cylinder has at least three cylinder chambers, and the hydraulic system includes a first hydraulic circuit and a second hydraulic circuit. The hydraulic system for use under water is set up, in particular, with a redundant hydraulic actuating drive for manual (mechanical) actuation.

A hydraulic thruster system for providing an axial force. In one embodiment, the system comprises a pump, a motor for driving the pump, and a hydraulic thruster comprising: a cylinder comprising a plurality of cylinder pistons; a shaft comprising a plurality of shaft pistons; a plurality of first pressure chambers; and a plurality of second pressure chambers, wherein the plurality of shaft pistons are positioned inside the cylinder, between the cylinder pistons to form the plurality of first and a second pressure chambers, wherein the shaft further comprises a first fluid passage connected to the pump and to the first pressure chambers, and a second fluid passage connected to the pump and to the second pressure chambers, and wherein the pump may pump fluid into the first pressure chambers and suction fluid from the second pressure chambers providing an axial force between the shaft and the cylinder.

One object is to reduce a weight of a fluid actuator. The fluid actuator includes: a cylinder having an inner space and a first mounting portion, the inner space being partitioned into a first fluid chamber and a second fluid chamber, the first mounting portion being disposed on an end portion of the cylinder on an axial direction A side; and a piston rod configured to reciprocate in accordance with pressures in the fluid chambers. A wall portion defining the first fluid chamber in the cylinder is made of an iron-based alloy. A wall portion defining the second fluid chamber in the cylinder is made of an aluminum alloy. The piston rod is made of an iron-based alloy.

An actuator includes: a casing; a pressure reducing valve and a piston. The pressure reducing valve is provided in the casing to reduce a pressure of a driving fluid supplied from an outside of the casing to a predetermined level. The piston is provided in the casing to form a pressure chamber together with the casing. The piston is driven by the driving fluid that has been pressure-reduced to the predetermined level.

A cylinder device includes: a first piston (8) inserted in a first cylinder hole (4) so as to be movable in an axial direction, a piston rod (7) being hermetically inserted in the first piston (8), the first piston (8) being fixed to the piston rod (7); a second piston (10, 37) inserted in a second cylinder hole (5) so as to be movable in the axial direction, the piston rod (7) being inserted in the second piston (10, 37); and a partition wall (13) dividing a cylinder hole (6) into the first cylinder hole (4) and the second cylinder hole (5), the partition wall (13) being movable in the axial direction.

The invention relates to a hydraulic fluid power transmission comprising: actuator apparatus having a plurality of chambers, each of the chambers having a respective fluid driving surface configured to drive or be driven by hydraulic fluid therein; a discretised pressure control system configured to selectively connect one or more first chambers of the said plurality of chambers to one of a plurality of hydraulic fluid sources or sinks, at least two of the plurality of hydraulic fluid sources or sinks having different fluid pressures; a continuous pressure control system configured to control the pressure of hydraulic fluid, or a flow rate of hydraulic fluid, input to or output from one or more second chambers of the said plurality of chambers, the pressure or flow rate of the hydraulic fluid input to or output from the second chambers being thereby variable within a range of pressures or flow rates respectively; and a controller configured to control the discretised and continuous pressure control systems to thereby regulate a property of the actuator affected by the hydraulic fluid pressure in the said chambers.

An air cylinder includes a cylinder, a piston rod, a piston, and a controller. The piston rod has one end disposed in the cylinder and the other end protruding from the cylinder. The piston is provided at the one end of the piston rod and moves the piston rod by moving in the cylinder. The controller supplies gas into one of a space, which is a space in the cylinder directed on the piston rod side with respect to the piston, and a space, which is a space in the cylinder opposite to the space with respect to the piston, and sucks gas from an interior of the other of the spaces.

A hydraulic actuator has a lower cylinder comprising a lower cylinder extension area and a lower cylinder retraction area, an upper cylinder comprising an upper cylinder extension area and an upper cylinder retraction area, and an actuator shaft. The actuator shaft has a lower cylinder piston disposed in the lower cylinder, an upper cylinder piston disposed in the upper cylinder, a lower shaft connecting the lower cylinder piston to the upper cylinder piston, and an upper shaft extending from the upper cylinder piston and at least partially externally from the upper cylinder. At least one of fluid flow of the lower cylinder matches fluid flow of the upper cylinder and (1) an internal diameter of the lower cylinder is not equal to the an internal diameter of the upper cylinder and (2) a diameter of the lower shaft is not equal to a diameter of the upper shaft.