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).

In order to reduce fluid consumption, a fluid return apparatus is provided for a double-acting cylinder having a first fluid connection for supplying fluid to a first cylinder chamber of the cylinder and a second fluid connection for supplying fluid to a second cylinder chamber at a piston rod-side of the cylinder. The fluid return apparatus comprises a first fluid passage providing fluid communication between the first fluid connection and the first cylinder chamber; a rapid venting valve comprising an inlet providing communication with the second fluid connection; an outlet providing communication with the piston-rod-side second cylinder chamber; a vent of the rapid venting valve, connected by a second fluid passage to the first fluid passage; and a non-return fitting in the second fluid passage, which prevents fluid from flowing from the first fluid passage to the rapid venting valve and an auxiliary outlet device.

The present invention provides an improved high-low hydraulic system for compacting machinery, such as balers, horizontal balers, compactors, transfer station compactors, and the like. The high-low hydraulic system comprises at least one double rotary pump, a plurality of directional control valves, a pilot-operated back pressure reducing valve, a flow control valve, a plurality of one-way valves, and a plurality of pressure switches. The high-low hydraulic system may be regenerative or non-regenerative and provides many advantages over conventional hydraulic systems. Such advantages include greater system efficiency due to a reduced back pressure during the time of the retraction stroke and clever flow sequencing, mitigation of hydraulic shocks at the beginning and end of compaction and retraction strokes, and reduced cycle time of the cylinder during operation due to the concurrent filling of the rod end side during decompression of the blind end side after the compaction stroke. Moreover, the present high-low hydraulic system allows for the cylinder to operate at three or more independent speeds. Additionally, the present high-low hydraulic system may also comprise an accumulator and pressure transducer that further assist with substantially maintaining a predetermined hydraulic pressure on the blind end side after the completion of the compaction stroke.

The invention relates to a hydraulic cylinder, for example for use in a hydraulic tool, comprising at least one piston/cylinder combination composed of a cylinder body and a piston accommodated in said cylinder body and provided with a piston rod that projects from said cylinder body, wherein the cylinder body and the piston body define a first cylinder chamber while the cylinder body, the piston body and the piston rod define a second cylinder chamber, and wherein during operation the piston performs alternating forward and return operational cycles under the influence of a fluidum under pressure that is conducted to the first and the second cylinder chamber through a first and a second line, respectively, and a control valve which regulates the supply of a fluid under pressure through the first or the second line to the piston/cylinder combination.

Provided is a hydraulic drive system for a work machine configured with a single solenoid proportional valve for a regeneration circuit, wherein substantially the same actuator speed can be secured irrespective of whether or not hydraulic fluid discharged from a hydraulic actuator is regenerated for driving of another hydraulic actuator. The hydraulic drive system includes: a regeneration line that connects a bottom-side hydraulic chamber of a hydraulic cylinder 4 to a portion between a hydraulic pump device 50 and a second hydraulic actuator 8, and a regeneration flow rate adjustment device that supplies, at an adjusted flow rate, at least part of the discharged hydraulic fluid to a portion between the hydraulic pump device 50 and the second hydraulic actuator; a discharge flow rate adjustment device that discharges, at an adjusted flow rate, the discharged hydraulic fluid to a tank; one electric drive device 22 that simultaneously controls the regeneration flow rate adjustment device and the discharge flow rate adjustment device; and a control unit 27 that outputs a control command to the electric drive device in such a manner that falling speed of a first driven body does not vary significantly, irrespective of the magnitude of the regeneration flow rate caused by the regeneration flow rate adjustment device.

Disclosure herein are hydraulic systems and method of use thereof. The hydraulic systems can include a hydraulic cylinder and a manifold. The hydraulic cylinder can have a first end and a second end. The hydraulic cylinder can include a first port, a second port, and a third port. The first port can be located proximate the first end. The second port cane be located proximate the second end. The third port can be located in between the first port and the second port. The manifold can include a first valve and a second valve. The first valve can be in fluid communication with the first port and the third port. The second valve can be in fluid communication with the second port and the third port.

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).

Disclosure herein are hydraulic systems and method of use thereof. The hydraulic systems can include a hydraulic cylinder and a manifold. The hydraulic cylinder can have a first end and a second end. The hydraulic cylinder can include a first port, a second port, and a third port. The first port can be located proximate the first end. The second port cane be located proximate the second end. The third port can be located in between the first port and the second port. The manifold can include a first valve and a second valve. The first valve can be in fluid communication with the first port and the third port. The second valve can be in fluid communication with the second port and the third port.

Load-handling vehicle comprising: a load-handling member, a jack (4) for lifting the load-handling member, comprising a lifting chamber (5) and a lowering chamber (6), a fluid source (7), a first fluid connection (8) from the lifting chamber (5) to the source (7), a second fluid connection (9) from the lowering chamber (6) to the source (7), the first connection (8) comprising a safety valve (10) that is open in the direction of the fluid source (7) towards the lifting chamber (5), and that is normally closed in the direction of the lifting chamber (5) towards the fluid source (7). A valve (11) arranged on the second link (9) is sensitive to the pressure of the portion of the first link (8) extending between the valve (10) and the source (7), and a unidirectional fluid circulation line (12), which can be closed according to the pressure weighing on the portion of the second fluid connection (9) between the valve (11) and the source (7), connects the first and second connections (8, 9).

The invention relates to a timber handling vehicle (1) and a timber grip, wherein said timber handling vehicle includes a load compartment (2), a crane (3) a timber grip (4), a hydraulic cylinder (4c), a hydraulic system (11, 12), a pump (15), a tank (16), a control valve (18) with which a fluid flow set under a pump feed pressure (P) is directed to a plus side (15:1) via a first pipe (15A) respectively a minus side (15:2) via a second pipe (15B). For efficient timber handling, the hydraulic system (11, 12) includes a third pipe (15C), which results in a regenerative fluid flow from the minus side (15:2) to the plus side (15:1) of the hydraulic cylinder (4c), a valve means (21) in the second pipe (15B), which valve means (21) is configured to; drive in a first operating condition, where the valve means (21) is closed and fluid flow from the minus side (15:2) to the plus side (15:1) of the hydraulic cylinder is directed via said third pipe (15C), receive a pressure indication that indicates a pump feed pressure (P) on the plus side (15:1) of the hydraulic cylinder (4c), determine whether the pump feed pressure (P) exceeds a first operating condition threshold value (Z1) and, if so, drive in a second operating condition, where the valve means (21) is open, and fluid flow from the minus side (15:2) of the hydraulic cylinder (4c) is directed to the tank (16).