The invention relates to a hydraulic cylinder, for example for use with a hydraulic tool, which hydraulic tool is provided with a frame and an element which is movable with respect to the frame by means of the hydraulic cylinder. A hydraulic tool which is operated by means of a hydraulic cylinder as described above is known from, for example, European patent no. 0641618. This patent discloses a frame which is coupleable to a jib of an excavator or the like and to which an assembly of two jaws can be coupled. One of the jaws is pivotable with respect to the other jaw by means of a hydraulic adjusting cylinder (a double-acting piston/cylinder combination).

The first piston of the first cylinder and the second piston of the second cylinder are connected so that the first piston and the second piston have the same displacement. The cross-section area of one side of the first piston is the smallest, and the cross-section area on the same side of the second piston is the third smallest. The two air chambers of the first cylinder and the two air chambers of the second cylinder are referred to as a first air chamber, a second air chamber, a third air chamber, and the fourth air in ascending order in the cross-section area. The control valve connects the air pressure source to the first air chamber, connects the second air chamber to the third air chamber, and opens the fourth air chamber to the atmosphere in the forward stroke.

A rack assembly for a rack and pinion gear system may comprise: a rack housing; and a rack disposed within the rack housing, the rack and the rack housing at least partially defining a first hydraulic chamber disposed between a first side of the rack and the rack housing, a second hydraulic chamber disposed between a second side of the rack and the rack housing, a third hydraulic chamber disposed within the rack proximal the first hydraulic chamber, and a fourth hydraulic chamber disposed within the rack proximal the second hydraulic chamber.

An actuator assist apparatus for use with an actuator has a housing and a piston member slidably disposed in the housing. The piston member divides the interior of the housing into a first fluid chamber and a second fluid chamber. The actuator assist apparatus is configurable between a first, primed, configuration and an activated configuration. A force applicator is configured to store energy when the apparatus is in the primed configuration and release the energy to move the piston member relative to the housing. Movement of the piston member applies a force which assists in urging the actuator towards an extended configuration, thereby reducing the minimum operating pressure of the actuator.

Provided is a cylinder connection assembly comprising a ventilation connection sleeve sleeved on a piston shaft of the cylinder, the ventilation connection sleeve fixedly provided in a cylinder barrel of the cylinder and separates an inner cavity of the cylinder barrel to form front and rear air chambers, a first ventilation hole communicating with the front air chamber and a second ventilation hole communicating with the rear air chamber are provided on the ventilation connection sleeve, so that when the compressed gas is filled into the front air chamber through the first ventilation hole, or the compressed gas is filled into the rear air chamber through the second ventilation hole, the piston assembly in the cylinder barrel can move axially. Through the ventilation connection sleeve provided in the cylinder barrel, the compressed gas can directly enter the front air chamber or the rear air chamber through the ventilation hole thereon.

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 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.

A cylinder has a piston part, a cylinder part, and a pipe section connected to the piston or cylinder parts. A portion of the pipe section encloses a pressure compartment which receives a fluid to apply a pressure on a pressure surface so the piston part is displaced in a first stroke direction. A first return pressure compartment receives a fluid to apply a pressure on a first return pressure surface so that the piston part is displaced in a second return stroke direction. The first return pressure compartment is positioned on the outside of the pipe section, and the area of the first return pressure surface is substantially equal to the area of the return pressure surface so that a volume-neutral operation of the cylinder is provided. Also described is a hydraulic system, an excavator comprising the cylinder and a procedure for operation of the cylinder.

The present disclosure relates to variable recruitment actuator systems and related methods. In one embodiment, a variable recruitment actuator system may include a high-pressure fluid connection and a plurality of actuators. A variable recruitment actuator mechanism may selectively recruit a subset of the plurality of actuators based on a position of the variable recruitment actuator mechanism by selectively placing the subset of the plurality of actuators in fluid communication with the high-pressure fluid connection. A control system to control the position of the variable recruitment actuator mechanism may operate based on an input from a user.

A walking excavator (1) having a superstructure (2) and an undercarriage (29), and a cab (3) disposed on the superstructure (2), and four walking legs (4) pivotably disposed on the undercarriage (29), and an excavator arm (5) which is pivotably mounted on the superstructure (2) and to which an excavating tool (6), in particular an excavator bucket, is fastened or able to be fastened. A dual-action differential cylinder (7) pivots the excavator arm (5) up and down relative to the superstructure (2) and is articulated on the superstructure (2), on one side, and on the excavator arm (5), on an other side. For applying additional force along with the dual-action differential cylinder (7) when pivoting the excavator arm (5) down relative to the superstructure (2), a single-action differential cylinder (8) is additionally articulated on the superstructure (2), on one side, and on the excavator arm (5), on an other side.