Inside a valve housing equipped with a first flow path and a second flow path that connect in parallel with a first port and a second port, there are provided a needle valve body that opens/closes a throttle hole in the first flow path, a check valve that opens/closes the second flow path, and a piston that performs an open/close control of the needle valve body through the interaction of the pressure of a fluid introduced into a pressure chamber and the spring force of a compression spring. The needle valve body is formed at the tip of a rod coupled to the piston. Inside the rod and the needle valve body there is formed a conduction hole connecting the throttle hole and the pressure chamber.

A valve system for use with a cylinder having an extensible rod. includes a first valve assembly including a first inlet/outlet port, a check valve biased toward a closed suite, the cheek valve 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 first inlet/outlet port and the check valve, and a first pilot port selectively communicable with a pressurized gas for opening the check valve. The valve system further include a second valve assembly including a second inlet/outlet port, a second pilot port through which the pressurized gas must flow before being introduced to the first pilot port, and a valve body at least partially receivable within a second port of the cylinder, wherein the second inlet/outlet port and the second pilot port are integrally formed as a portion of the valve body.

A valve system for use with a cylinder having an extensible rod, includes a first valve assembly including a first inlet/outlet port, a check valve biased toward a closed state, the check valve 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 first inlet/outlet port and the check valve, and a first pilot port selectively communicable with a pressurized gas for opening the check valve. The valve system further includes a second valve assembly including a second inlet/outlet port, a second pilot port through which the pressurized gas must flow before being introduced to the first pilot port, and a valve body at least partially receivable within a second port of the cylinder, wherein the second inlet/outlet port and the second pilot port are integrally formed as a portion of the valve body.

A safe hydraulic drive system and process, comprising at least one first cylinder chamber and a second, separate cylinder chamber which are connected to one another via a connecting line to form a fluid-filled hydraulic circuit, and a hydraulic drive for conveying the fluid from one cylinder chamber, via the connecting line, into the other cylinder chamber in which the connecting line is arranged. The connecting line has at least one parallel system, between the hydraulic drive and one of the two cylinder chambers, including at least one first sub-connection with at least one first stop valve and a second sub-connection with a baffle arranged therein. The connecting line, excluding the second sub-connection, has a first flow resistance and the second sub-connection has a second flow resistance due to the baffle arranged therein, which is greater than the first flow resistance for the fluid, wherein the drive system is provided with at least one open first stop valve in normal mode and with a closed first stop valve in safe mode for conveying the fluid, and a suitably high second flow resistance has been selected so that a maximum permissible speed for a piston rod is not exceeded in safe mode, even when an external force acts on the drive system in the direction of movement of the piston rod.

An electromagnetic switching valve, for which the maximum opening is set to be small, is disposed on piping between a lift cylinder and a hydraulic pump motor. A pilot check valve, for which the maximum opening is set to be larger than the electromagnetic switching valve, is disposed on piping, different from the piping, between the lift cylinder and the hydraulic pump motor. In addition, during lowering operations, first, the electromagnetic switching valve is opened, and then after the same is opened, the pilot check valve is opened after a prescribed time has passed. Thus, the shock generated when lowering an object to be raised/lowered is reduced and a fork is operated quickly.

A valve system, for use with a cylinder having an extensible rod, includes a first valve assembly having a first inlet/outlet port, a check valve biased toward a closed state, the check valve 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 first inlet/outlet port and the check valve, and a first pilot port selectively communicable with a source of pressurized gas for opening the check valve. The valve system further includes a second valve assembly having a second inlet/outlet port, a second pilot port through which the pressurized gas must flow before being introduced to the first pilot port, and a valve body at least partially receivable within a second port of the cylinder.

A hydraulic driving system includes a hydraulic pump, a driving source, a hydraulic cylinder, a closed circuit hydraulic path between the pump and cylinder, a pump-flow-rate control unit controlling a discharge flow rate of the pump, a flow rate control valve between the pump and the cylinder in the fluid path, a directional control unit, a target flow rate setting unit and a control device. The directional control unit allows a flow of fluid from the pump to the cylinder and prohibits a flow of fluid from the cylinder to the pump when fluid is supplied from the pump to the cylinder via the flow rate control valve. The control device controls fluid flow to the cylinder with the flow rate control valve when the target flow rate is within a prescribed range, and with the pump-flow-rate control unit when the target flow rate is greater than the prescribed range.

A regulator valve has a check valve manifold for use in subsea control circuits. For example, the regulator valve having the check valve manifold can be used in a circuit between a directional control valve and an actuator for a gate valve. The check valve manifold can have a flange that attaches to the regulator valve to communicate with the supply-side and outlet-side of the regulator valve. Internal communication inside the manifold includes a check valve. If the pressure in the circuit downstream of the regulator valve needs to be vented, the check valve can open to allow the pressure to bleed from the outlet-side back to the supply-side without needing to pass through the internal pressure control valve of the regulator.

A two-stage speed controller includes a main body including a first port and a second port in communication with each other, and a primary channel and a secondary channel for fluid to flow therethrough. The secondary channel allows flowing in a single direction to a pressure accumulation chamber. A sliding-axle seat is arranged in the second port. An end of a sliding axle assembly forms, together with the sliding-axle seat, a valve. The pressure accumulation chamber is connected with a primary throttle channel. The sliding axle assembly is formed, in a transverse direction, with a secondary throttle channel. During ingress and discharging of the fluid, all the channels and movement of the valve together allow for control of the pressure of the fluid according to a magnitude of a spring force of a regulation assembly in order to control a moving speed of a cylinder connected to the main body.

A two-stage speed controller includes a main body including a first port and a second port in communication with each other, and a primary channel and a secondary channel for fluid to flow therethrough. The secondary channel allows flowing in a single direction to a pressure accumulation chamber. A sliding-axle seat is arranged in the second port. An end of a sliding axle assembly forms, together with the sliding-axle seat, a valve. The pressure accumulation chamber is connected with a primary throttle channel. The sliding axle assembly is formed, in a transverse direction, with a secondary throttle channel. During ingress and discharging of the fluid, all the channels and movement of the valve together allow for control of the pressure of the fluid according to a magnitude of a spring force of a regulation assembly in order to control a moving speed of a cylinder connected to the main body.