A hydraulic arrangement includes a working pump for conveying a hydraulic medium in a direction of a hydraulic working load, a hydraulic tank comprising a tank outlet hydraulically connected to an inlet side of the working pump, and an auxiliary pump mounted in the hydraulic tank. A hydraulic flow of the hydraulic medium flows in the direction of the tank outlet in dependence on a control system.

A working machine includes a branched tube connected to a branched portion branching from an operation fluid tube, a plurality of input tubes connected to the second actuator valves, a plurality of output tubes connected to a pressure receiver portion of the second hydraulic device, a main tube connected to the third actuator valve, and a relay device, and the relay device includes a plurality of input ports connected to the plurality of input tubes, a plurality of output ports connected to the plurality of output tubes, a plurality of first flow lines connecting between the plurality of input ports and the plurality of input ports, a main port connected to the main tube, a branched port connected to the branched tube, and a second flow line arranged between the plurality of first fluid lines to connect between the main port and the branched port.

A boom lift system includes a primary conduit, a pump-motor arrangement having a motor operable to drive a pump to move a fluid through the primary conduit, first and second actuators in fluid communication with the primary conduit and actuatable in response to first and second user input to perform hydraulic function via the fluid, a valve arrangement configured to control flow of the fluid from the primary conduit to the first and second actuators, and a controller programmed to selectively actuate the valve arrangement in response to the first and second user inputs. When the controller receives both of the inputs, the valve arrangement is actuated by the controller to vary the flow rate of fluid to each of the first and second actuators. When the controller receives only one of the first input or the second input, the controller varies a flow rate output of the pump.

A ride control valve includes a valve body defining a work passage, a pump passage, a tank passage, and an accumulator passage configure to couple to an accumulator. A ride control spool is movably disposed within the valve body and configured to move between a a first ride control position to discharge the accumulator, a second ride control position configured to charge the accumulator at a variable charge rate, a third ride control configured to balance the accumulator pressure with the work passage pressure, and a fourth ride control position configured to couple the accumulator to the work passage. A pressure balancing spool is movably disposed within the ride control spool to selectively couple the accumulator passage with each of the pump passage and the tank passage to balance the accumulator pressure. The ride control valve is configured couple to a directional control valve without external conduit.

An attachment is attached to an upper turning body. During a normal operation, a drive means drives the attachment according to an input of an operator to a manipulation device. A sensor detects a motion of an excavator. Based on an output of the sensor, the slip suppression unit detects slip of a traveling body in an extension direction of the attachment and corrects an operation of the attachment performed by the drive means.

Lever neutrality is determined by whether or not operation levers are at a neutral position based on operation signals from operation levers. Pilot pressures are computed based on the operation signals from the operation levers; and pilot pressure signals are converted to current signals. A current interruption controller controls interruption and communication of the current signals to the solenoid proportional valves; and an operating condition is determined by determining whether a construction machine is in a manual operation state or a semiautomatic operation state. At least one hydraulic actuator is controlled to assist the operation of the operator, and when it is determined that the construction machine is in the semiautomatic operation state, the current interruption controller interrupts the current signals to all of the solenoid proportional valves only when it is determined that all the operation levers are at the neutral position.

A hydraulic breaker provided with an automatic lubricant supply structure is proposed. The automatic lubricant supply structure is configured to automatically supply a lubricant without a separate hose, using a working fluid, and is disposed in the body of the hydraulic breaker, and can be used without a separate external part.

A work machine is provided. The work machine includes a changeover valve capable of disabling area limiting control by bypassing an area limiting control solenoid proportional valve disposed in a pilot line through which pilot pressure generated by a hydraulic pilot type operation device is guided to a directional control valve and the work machine can perform the area limiting control while ensuring response of a work implement. When a first fluid temperature T1 is higher than a first predetermined temperature Ta and a control changeover switch 66 specifies disabling of the area limiting control, a controller brings a plurality of changeover valves into a bypass position. When the first fluid temperature T1 is equal to or lower than the first predetermined temperature Ta, the controller brings the changeover valves into a communication position and places the solenoid proportional valves in a fully open position.

In a hydraulic drive system for an electrically driven hydraulic work machine that executes flow rate control of a hydraulic pump by controlling a rotation speed of an electric motor to drive a hydraulic pump to supply a hydraulic fluid to a plurality of actuators, and power consumed by the electric motor reliably limited within a range of preset maximum allowable power without unnecessary degradation of responsiveness of the electric motor. To this end, a controller includes a maximum angular acceleration limitation section (allowable rate computation section and rate limitation section), computes hydraulic power consumed by a main pump, computes a maximum angular acceleration allowed for an electric motor on the basis of a magnitude of the hydraulic power and a preset maximum allowable power consumable by the electric motor, and limits an angular acceleration of the electric motor not to exceed the maximum angular acceleration.

Example embodiments relate to a skid steer trimmer assembly usable for contouring the ground.