A counter pressure valve arrangement for controlling a pressure level of a hydraulic fluid in a return line from a hydraulic actuator arrangement. The counter pressure valve arrangement comprises a counter pressure valve having: a moveable valve member; a counter pressure regulating port configured for being connected to the hydraulic actuator arrangement via the return line; a tank port configured for being connected to a tank or low pressure reservoir for storing low pressure hydraulic fluid; and a pump port configured for being connected to a source of pressurised hydraulic fluid. A first position of the valve member effects fluid communication between the pump port and the counter pressure regulating port for supplying pressurised hydraulic fluid to the return line, and a second position of the valve member effects fluid communication between the counter pressure regulating port and the tank port for discharging hydraulic fluid from the return line to the tank.

A time delay valve includes a switching valve that switches between a first position and a second position; an urging member that urges the switching valve toward the first position; a driving mechanism that urges the switching valve toward the second position located opposite the first position in the presence of the pressure of a pilot fluid being supplied: a pilot flow channel that introduces the pilot fluid to the driving mechanism; and a delaying mechanism that delays the switching timing of the switching valve. The delaying mechanism includes a first throttle valve provided on the pilot flow channel, a compensation mechanism that urges the switching valve toward the first position in the presence of the pressure of the pilot fluid being supplied, and a compensation flow channel that is branched from the pilot flow channel to introduce a portion of the pilot fluid to the compensation mechanism.

The invention relates to a compressed-air supply system for operating a pneumatic installation in a pneumatic system of a vehicle, comprising: a compressed-air feed; a compressed-air connection point to the pneumatic installation; a venting connection point to the environment; a pneumatic main line between the compressed-air feed and the compressed-air connection point, which pneumatic main line has an air dryer; a venting valve, which is arranged on the pneumatic main line and is designed as a pilot valve and has a pilot connection point; a compressor having at least one compressor stage; and, in addition to the pneumatic main line, a pilot valve and a pneumatic pilot channel that connects the pilot valve to the pilot connection point of the venting valve. With respect to the compressed-air supply system, according to the invention, a pressure-holding pneumatic reservoir device is connected to the pilot connection point, which reservoir device is designed to provide a control pressure for the pilot connection point, in particular independently of a pressure in the pneumatic main line during venting of the pneumatic system, and the pressure-holding pneumatic reservoir device has at least one separate pilot pressure accumulator, which can be pneumatically connected to the pilot connection point via the control line.

A system for controlling hydraulic fluid flow within a work vehicle includes a load sense valve configured to adjust the pressure of a bleed flow within a load sense conduit. Moreover, the system includes a computing system configured to determine the pressure of the hydraulic fluid within the fluid supply conduit downstream of the flow control valve based on the data captured by a pressure sensor. Furthermore, the computing device is configured to control an operation of the load sense valve to selectively adjust the pressure of the bleed flow within the load sense conduit based on the determined pressure.

A working machine includes a machine body, a first hydraulic actuator mounted on the machine body, a first control valve that controls the first hydraulic actuator, a controller that controls the first control valve, and a second hydraulic actuator that is different from the first hydraulic actuator. When the second hydraulic actuator and the first hydraulic actuator are operated in combination, the controller reduces the amount of change in the flow rate of a hydraulic fluid supplied from the first control valve to the first hydraulic actuator with respect to changes in a manipulation amount to operate the first hydraulic actuator to a value smaller than that when the first hydraulic actuator is solely operated.

A hydraulic system includes: hydraulic actuators; a control valve for controlling the hydraulic actuators; a tank for storing a hydraulic operation fluid; a variable displacement pump for supplying the hydraulic operation fluid to the hydraulic actuators; a regulator for controlling the variable displacement pump; a pilot pump for discharging a hydraulic pilot fluid; a load sensing system for maintaining a differential pressure to be a constant pressure, the differential pressure being obtained by subtracting a second signal pressure from a first signal pressure that is the discharge pressure of the variable displacement pump, the second signal pressure being the maximum one of the load pressures generated in the hydraulic actuators; a signal tube for sending the second signal pressure to the regulator; a throttle provided on the signal tube; and a warm-up circuit for supplying the hydraulic pilot fluid to a downstream side of the throttle.

A hydraulic circuit with a compensation and energy recovery function includes a distribution module having at least one spool defining a main delivery branch and a discharge branch. The hydraulic circuit also includes a supply unit and a three-way compensated adjustment device connected to the spool discharge branch and connected to discharge at a second channel. The three-way compensated adjustment device further includes a first piloting line and a second piloting line configured so that a Maximum Load Sensing piloting signal acts on a first side and a Local Load Sensing piloting signal acts on the second side. An energy recovery device and a selection section are configured to receive a signal at reduced pressure and send it to the first piloting line to activate the three-way compensated adjustment device switching to a position where the fluid coming from the discharge branch is sent to the energy recovery device.

A hydraulic excavator 1 includes an engine 16, a main hydraulic pump 17 driven by the engine 16, a plurality of hydraulic actuators driven with pressure oil discharged from the main hydraulic pump 17, a plurality of flow rate control valves adapted to control the flow rate of pressure oil to be supplied from the main hydraulic pump 17 to the respective hydraulic actuators, a pilot hydraulic pump 18 adapted to supply pressure oil for driving the flow rate control valves, and a controller 15 configured to control the discharge flow rate of the pilot hydraulic pump 18. The controller 15 controls the discharge flow rate of the pilot hydraulic pump 18 such that it becomes equal to the sum of requested pilot flow rates determined in accordance with control commands for the respective flow rate control valves and a preset standby flow rate.

A hydraulic system for a working machine includes a hydraulic actuator having a first fluid chamber and a second fluid chamber, an accumulator, an outputting fluid tube to output an operation fluid, and a switching valve to be switched between a first position and a second position. The first position allows the first fluid chamber and the second fluid chamber to be communicated with the outputting fluid tube and thereby allowing a floating operation. The second position allows the first fluid chamber and the accumulator to be communicated with each other, allows the second fluid chamber and the outputting fluid tube to be communicated with each other, and thereby allows an anti-vibration operation.

A system for controlling hydraulic fluid flow within a work vehicle includes a load sense valve configured to adjust the pressure of a bleed flow within a load sense conduit. Moreover, the system includes a computing system configured to determine the pressure of the hydraulic fluid within the fluid supply conduit downstream of the flow control valve based on the data captured by a pressure sensor. Furthermore, the computing device is configured to control an operation of the load sense valve to selectively adjust the pressure of the bleed flow within the load sense conduit based on the determined pressure.