A hydraulic system includes a hydraulic pump, an output fluid tube connected to the hydraulic pump, an operation fluid tube connected to a hydraulic device, an unload valve connected to the output fluid tube, and having: a supply position in which the operation fluid in the output fluid tube is supplied to the operation fluid tube; and a restrain position in which supply of the operation fluid to the operation fluid tube is restrained, an operation valve connected to the output fluid tube, a control fluid tube connecting the operation valve and the hydraulic device, a warmup fluid tube connecting the control fluid tube and the operation fluid tube, and a check valve provided in the warm-up fluid tube and being for allowing the operation fluid to flow from the control fluid tube side toward the operation fluid tube, and for blocking the operation fluid from flowing side from the operation fluid tube toward the control fluid tube.

A hydraulic system includes a first system discharge fluid tube that discharges fluid flowing through a first supply fluid tube, a second system discharge fluid tube that discharges fluid, a first control valve, and a second control valve connected to a second supply fluid tube, the first system discharge fluid tube, and the second system discharge fluid tube, configured to be switched between: a supply position that supplies fluid from the second supply fluid tube to the first supply fluid tube; a first stop position that stops supply of fluid from the second to the first supply fluid tube and supplies fluid from the first supply fluid tube to the first system discharge fluid tube; and a second stop position that stops supply of fluid from the second to the first supply fluid tube and supplies fluid from the first supply fluid tube to the second system discharge fluid tube.

A valve system for use with a cylinder having an extensible rod, includes first and second valve assemblies, each including an inlet/outlet port configured to selectively be coupled with a source of pressurized gas, a check valve biased toward a closed state and having a check valve body at least partially receivable within a first port of the cylinder, a flow control valve positioned in series between the inlet/outlet port and the check valve, and an inlet pilot port connected with the check valve for opening the check valve when supplied with pressurized gas. First and second pilot lines extend to the respective inlet pilot ports from respective outlet pilot ports of the opposite ones of the first and second valve assemblies. When pressurized gas is supplied to the inlet/outlet port of a valve assembly, pressurized gas is also supplied to the opposite inlet pilot port.

A safety system has a valve block (10) to which at least one gas safety valve (12, 14) is connected in a detachable manner. At least one controllable valve (50, 52, 58) is in or at the valve block (10). At least one pressure accumulator (42) holds a gaseous pressure medium and is connected to the valve block (10) in a detachable manner. A gas-conveying connection routed at least partially within the valve block (10) between the connected pressure accumulator (42) and the connected gas safety valves (12, 14) can be opened or blocked by the valve (50, 52, 58).

In accordance with an example embodiment, a hydraulic system may include a pump, reservoir, accumulator, hydraulic cylinder, ride control valve assembly, and controller. The ride control valve assembly may include a charging valve, discharging valve, and a head ride control valve. The controller may open the head ride control valve when a ride control feature has been activated, or open the charging valve if the ride control feature has not been activated and a hydraulic fluid warmup is to be performed.

A fluid pressure control device includes a switching valve, a main pilot passage and a sub pilot passage, the switching valve is configured to be switched to the open position when the working fluid is supplied to the pilot chamber, and to be switched to the throttled position with opening on the downstream side of the switching valve in the neutral passage, and the sub pilot passage is provided with a throttle portion and a check valve in parallel in the throttle portion.

A hydraulic device is provided. Working fluid stored in a fluid storage portion is supplied by a fluid supply portion to a power output portion. The fluid supply portion is driven by a brushless motor. A bypass flow path portion can be switched between a first state of supplying the working fluid from the fluid supply portion to the fluid storage portion and a second state of blocking the fluid supply portion from the fluid storage portion. A control to switch the bypass flow path portion from the first state to the second state after the brushless motor is started and a control to switch the bypass flow path portion from the second state to the first state when the brushless motor is stopped is performed. Backflow of the working fluid from the power output portion to the bypass flow path portion is prevented by a backflow prevention valve.

An electro-hydrostatic actuating drive has a variable-volume and/or variable-speed hydraulic machine, which is driven by an electric motor, for the provision of a volumetric flow of a hydraulic fluid. Furthermore, the actuating drive comprises a cylinder with a piston, a piston rod and a first piston chamber, a valve with a first position and a second position, which valve can be moved by a first hydraulic actuator into the first position and by a second hydraulic actuator into the second position, wherein the second position controls a greater volumetric flow of the hydraulic fluid than the first position, a sink, a main line which connects a first piston chamber of the cylinder to the sink and in which the hydraulic machine is arranged, an auxiliary line which connects the first piston chamber to the sink and in which the valve is arranged, a first control line to the first hydraulic actuator, and a second control line to the second hydraulic actuator. A hydraulic resistor is arranged in the main line in series with the hydraulic machine, the first control line is connected to the main line, and the second control line is connected between the hydraulic resistor and the first piston chamber.

An air cylinder in which a flow rate controller is built in, has a head cover and a rod cover. A pilot air adjustment unit guides exhaust air to a switch valve of the flow rate controller as pilot air, and the switch valve is switched by an increase in the pressure of the pilot air.

A hydraulic valve assembly includes a first spool valve and a first selector valve for actuating a first hydraulic consumer port or a second hydraulic consumer port, and a second spool valve and a second selector valve for actuating a third hydraulic consumer port or a fourth hydraulic consumer port. A shut-off valve is arranged in a common pressure channel. A branch channel with first and second pressure branch channels branches off the pressure channel upstream of the shut-off valve. The first selector valve connects the first pressure branch channel to a first connection line in a first switching position and connects the second pressure branch channel to a second connection line in a second switching position. The second selector valve, in a first switching position, connects the first connection line to the control channel and, in a second switching position, connects the second connection line to the control channel.