A load sensing valve maintains a differential pressure at a set pressure by controlling a regulator in accordance with a differential pressure between a discharge pressure of a hydraulic pump and a load pressure of hydraulic actuators. A set pressure control device controls the set pressure. A controller controls the set pressure control device to reduce the set pressure more than when the work implement is being operated, when a predetermined determination condition that includes the work implement not being operated is satisfied.

Disclosed is a device for relieving pressure in hydraulic lines, in particular in connecting lines that have coupling points (6, 8) and are located between attachments comprising hydraulically actuated actuators and working implements supplying said attachments. The disclosed device comprises a control block (2) which is connected to the line to be relieved and which includes an openable non-return valve (12) as a relief valve, a pressure accumulator (22) which holds a relieving volume when the non-return valve is open, and an actuating member (38) which can be moved manually in order to open the non-return valve (12) and which is arranged so as to be movable on the housing (24) of the pressure accumulator (22).

A work machine including a prime mover, an electric motor, an electric motor fluid circuit, a transmission fluid circuit, a hydraulic circuit, a cooling circuit, a pump, and a controller. The electric motor may supply a portion of power of the prime mover. The electric motor fluid circuit may be adapted to remove waste heat from the electric motor. The transmission fluid circuit may be adapted to lubricate a moving part of a transmission powered by the prime mover. The hydraulic circuit may be adapted to transmit power from the prime mover to a moving component of the work machine. The cooling circuit may be absorbing waste heat from one or more of the electric motor fluid circuit, the transmission fluid circuit, and the hydraulic circuit. The control may be adapted to control diversion of a portion of waste heat from the cooling circuit to a portion of the cab.

A quick coupler which features a safety mechanism which facilitates ease of use and assures safe use in the workplace by use of hydraulic circuits designed to automatically reset the safety locking mechanism on intentional removal of a front pin, including use of a 2-line hydraulic supply to the coupler.

An excavator includes a hydraulic oil holding circuit that is provided in an oil passage between a bottom-side oil chamber of a boom cylinder and a control valve and is closed when the boom is not lowered, and a controller. The controller releases a closed state of the hydraulic oil holding circuit when the excavator is in a predetermined unstable state, and controls a released state so that an acting velocity in a lowering direction of the boom becomes less than or equal to a predetermined reference.

The invention relates to a construction machine such as a road paver with an electric generator. The construction machine comprises a hydraulic oil system for hydraulic functions that also cools the generator.

A pump apparatus comprises a primary pump having a relatively low pressure fluid input and a relatively high pressure fluid output and means, associated with said primary pump fluid input, operable where the ambient pressure is insufficient substantially to prevent cavitation in the primary pump, to locally increase the pressure at said primary pump fluid input.

A working machine includes a fan motor driven with hydraulic fluid, the fan motor including a first port and a second port, a bypass fluid passage connecting the first port of the fan motor and the second port to each other, a flow rate control valve provided on the bypass fluid passage to control a flow rate of the hydraulic fluid flowing in the bypass fluid passage, a drain passage configured to drain the hydraulic fluid upstream of the flow rate control valve, and an unloading valve shiftable between a full-closing position to close the drain passage and a full-opening position to open the drain passage.

A device mounting structure for mounting a load maintaining mechanism on a hydraulic cylinder, a pipe for suppling and discharging working oil to and from the hydraulic cylinder being connected to the load maintaining mechanism such that the working oil is led thereto, includes a single coupling portion that includes a screw hole and is provided on the hydraulic cylinder, and a bracket to which the load maintaining mechanism is fixed, the bracket being coupled to the coupling portion via a first screw member that is screwed into the screw hole, wherein the bracket includes a first through hole through which the first screw member is passed so as to leave a gap in a radial direction.

A hydrostatic drive includes a hydraulic machine, a hydraulic adjusting device, a high-pressure accumulator, an accumulator-closing valve, and an electronic control unit. The hydraulic machine has a swept volume that is adjustable via the hydraulic adjusting device from a maximum positive swept volume to a maximum negative swept volume via a zero swept volume. The hydraulic machine is operated as a pump with positive swept volume and as a motor with negative swept volume. The high-pressure accumulator supplies the hydraulic machine with pressure medium for operation as a motor via a pressure line. The accumulator-closing valve has a first position and a second position and is arranged in the pressure line. A fluidic connection from the high-pressure accumulator to the hydraulic machine is open in the first position and closed in the second position. The accumulator-closing valve is actuated in accordance with signals from the electronic control unit.