A hydraulic machinery may include: a boom actuator including a large chamber and a small chamber; a tank; and an energy recovery circuit provided between the boom actuator and the tank, wherein the energy recovery circuit includes: a discharge valve provided between the large chamber and the tank to allow or block the flow of fluid from the former to the latter; a regeneration valve connecting the large chamber and the small chamber to allow or block the flow of fluid from the former to the latter; a recovery part for recovering energy; and a first valve provided between the large chamber and the recovery part to allow or block the flow of fluid from the former to the latter.

An excavator or other work machine includes a tilting bucket operated by a hydraulic actuator controlled by a bucket control valve responsive to control signals including a bucket shake control signal, which causes the bucket to move repeatedly in the rack and dump directions to shake debris from the bucket in a bucket shake operation. The actuator is powered by pressure from a hydraulic pump, and a control system includes an unloader valve to relieve pressure from the supply line to unload the pump when there is no demand for power. The control system is arranged to maintain a constant pressure signal in a load sensing line, to maintain the unloader valve constantly in a closed condition, for the duration of the bucket shake operation. This may be achieved by pressurising an actuator of a quick coupler to lock the bucket to the machine.

A main valve throttle (53) of a main valve (43) is configured by a lateral hole (53A) communicating an inlet side flow passage (25) and an outlet side flow passage (27) through the inside of the main valve (43) and a groove portion (53C) communicating the inlet side flow passage (25) and the outlet side flow passage (27) via an outer peripheral portion of the main valve (43). The groove portion (53C) is located such that a hydraulic fluid spurting from the groove portion (53C) changes the direction of a flow of a hydraulic fluid spurting from the lateral hole (53A). In this case, the direction of a flow of a hydraulic fluid F2 spurting from the lateral hole (53A) can be changed to approach the direction parallel to the center axis of the main valve (43) by a hydraulic fluid F1 spurting from the groove portion (53C).

Power machines and control systems used thereon include a lift cylinder, a tilt cylinder, and a slave cylinder mechanically connected to assist the lift cylinder with raising a boom. With a lift control valve controlled to cause extension of the lift cylinder to raise the boom, pressure from a hydraulic source is provided to the slave cylinder to aid in raising the boom. Resulting increased pressure on a side of the slave cylinder opens load holding valves, allowing hydraulic pressure from the tilt cylinder to be communicated to the slave cylinder such that tilt cylinder pressure due to a heavy load on an implement aids in raising the boom.

A control system for construction machinery includes a hydraulic cylinder operable by a working oil discharged from a hydraulic pump, a control valve arranged between the hydraulic pump and the hydraulic cylinder to control an operation of the hydraulic cylinder according to a position of a spool therein, the control valve having a first spool position for draining the working oil discharged from a chamber of the hydraulic cylinder to a drain tank, and a pressure compensated valve installed in a return hydraulic line through which the working oil discharged from the control valve at the first spool position is drained to the drain tank, the pressure compensated valve being configured to control a flow rate of the working oil passing through the pressure compensated valve according to a pressure difference between a front end and a rear end of the control valve.

A quick-change system for changing attachments on a construction machine with a quick coupler arranged to be pivotable about a pivot axis orthogonal to the axis of rotation by means of a hydraulic slewing drive and rotatable about an axis of rotation on a connection part by means of a hydraulic rotary drive contains mounts and at least one locking element which can be actuated by means of a hydraulic drive to hold an attachment coupled to the quick coupler. The quick-change system includes a hydraulic control device, which contains a first control circuit to drive rotary drive and slewing drive, at least one additional control circuit to supply the attachment coupled to the quick coupler and a shuttle valve arrangement to expose the hydraulic drive to the higher pressures acting in the first or the at least one additional control circuit to activate the at least one locking element.

A control valve of hydraulic system for a working machine is provided, which includes a main body and a spool. The main body includes first, second, third, fourth and fifth ports, and first second, third, fourth and fifth inner fluid paths connected to the first, second, third, fourth and fifth ports, respectively. The spool is configured to move between a neutral position and a communicating position allowing fluid communication between the second inner fluid path and the fifth inner fluid path or between the first inner fluid path and the fifth inner fluid path. The spool includes a communicating hole configured to allow the fluid communication between the second port and the fourth port, or between the first port and the fourth port, when the spool is in a position between the communicating position and the neutral position.

The invention relates to a system for a work machine. The power system comprises a power-split continuously variable transmission for propulsion of the work machine and a hydraulic system for work hydraulics. The power-split continuously variable transmission has a hydrostatic branch and a mechanical branch. The hydrostatic branch comprises a first hydraulic machine and a second hydraulic machine. The hydrostatic branch comprises a first control valve fluidly connected to the first hydraulic machine and to the second hydraulic machine for controlling the flow of hydraulic fluid between the first hydraulic machine and the second hydraulic machine. The hydraulic system comprises at least one hydraulic actuator fluidly connected to a first port of the first hydraulic machine, and a second control valve for controlling the flow of hydraulic fluid to said at least one hydraulic actuator.

A hydraulic system for operating a hydraulic fall-back support of a work machine including at least one hydraulic fall-back support cylinder for tracking and limiting movements of a boom of the work machine and a hydraulic pump by means of which the fall-back support cylinder and at least one further hydraulic consumer can be supplied with hydraulic fluid. A stop valve having a blocking position and a passage position is connected between the hydraulic pump and the fall-back support cylinder, by means of which the stop valve and a load-bearing cylinder space of the fall-back support cylinder is blockable and a hydraulic store connected to the load-bearing cylinder space is provided between the stop valve and the fall-back support cylinder.

A hydraulic system for recovering potential energy of a load implement of a mobile construction vehicle. The hydraulic system includes first and second actuators and control valving. The first and second actuators are configured to be coupled to the load implement for controlling raising and lowering of the load element. The control valving is operable between a first position at which, during a lowering of the load implement, the control valving directs hydraulic fluid from one of the first and second actuators to an accumulator to charge the accumulator, and a second position at which the control valving directs hydraulic fluid from the accumulator to one or more of the first and second actuators to power the one or more of the first and second actuators to raise the load element.