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.

[Object] To make it possible to detect, with a single pressure sensor, a malfunction of two solenoid valves for switching flow paths and to quickly and reliably exhaust residual pressure in an air device through a solenoid valve.

[Solution] A residual pressure exhaust air circuit 1 includes: a main flow path 9 through which air from an air source 2 is supplied to an air cylinder 100; an exhaust flow path 10 through which air in the air cylinder 100 is exhausted; a first sensor 8 for detecting a malfunction of solenoid valves 12, 13; a detection flow path 11 through which air from the air source 2 is supplied to the first sensor 8; and the two solenoid valves 12, 13 that switch communication states among the main flow path 9, the exhaust flow path 10, and the detection flow path 11. The two solenoid valves 12, 13 are formed of two-position valves having first positions 12a, 13a at the time of OFF and second positions 12b, 13b at the time of ON and are synchronously ON/OFF controlled. When the two solenoid valves 12, 13 do not operate in synchronization with each other, the air from the air source 2 is supplied to the first sensor 8 to detect a malfunction of the two solenoid valves 12, 13, and at the same time, the air in the air cylinder 100 is exhausted through the solenoid valve 12, 13.

A stage assembly (10) includes a stage (14), and a fluid actuator assembly (24) that moves the stage (14). The fluid actuator assembly (24) includes a piston housing (32) that defines a piston chamber (34); (ii) a piston (36) that separates the piston chamber (34) into a first chamber (34A) and a second chamber (34B); (iii) a supply valve (38C) that controls the flow of the working fluid (40) into the first chamber (34A); and (iv) an exhaust valve (38D) that controls the flow of the working fluid (40) out of the first chamber (34A). The supply valve (38C) has a supply orifice (250G) having a supply orifice area, and the exhaust valve (38D) has an exhaust orifice (352G) having an exhaust orifice area. Moreover, the supply orifice area is different from the exhaust orifice area. Further multiple valves of different sizes can be used in combination for the supply and exhaust for each chamber (34A), (34B).

Provided is a hydraulic drive device, wherein the hydraulic drive device is provided with: a cylinder (101); a rod (103); a piston (102); a hydraulic pump (107); a tank (113); a valve (106) that can be switched between a positive state of connecting the hydraulic pump (107) and a head chamber (101h) and connecting a rod chamber (101r) and the tank (113), and a negative state of connecting the hydraulic pump (107) and the rod chamber (101r) and connecting the head chamber (101h) and the tank (113); and a confluence channel (114) at which, when the valve (106) is in the positive state, at least a portion of hydraulic oil going from the rod chamber (101r) to the tank (113) is merged into hydraulic oil going from the hydraulic pump (107) to the head chamber (101h).

An example valve includes a main stage, a pilot stage, and a solenoid actuator. The main stage includes a sleeve and a piston axially movable within the sleeve. The piston defines a cavity therein. The pilot stage includes a pilot pin received at, and axially movable in, the cavity of the piston, where the piston forms a pilot seat at which the pilot pin is seated when the valve is in a closed state. The solenoid actuator includes a solenoid coil, an armature, and a solenoid spring. The solenoid spring applies a biasing force in a distal direction on the pilot pin to seat the pilot pin at the pilot seat. Energizing the solenoid coil causes the armature to move in a proximal direction, thereby reducing the biasing force that the solenoid spring applies on the pilot pin.

A dual spool valve and methods of controlling hydraulic fluid that is moved to a hydraulic actuator of an aircraft. The dual spool valve may include first and second manifolds that each includes a movable spool. Multiple ports are positioned in each of the manifolds. The movable spools are positionable within their respective manifolds to control the movement of the hydraulic fluid that is supplied to and removed from the hydraulic actuator.

The present invention relates to a hydraulic switch arrangement and a fluid switch for incorporating into a hydraulic switch arrangement that may be included in a hydraulic circuit for inhibiting flow of hydraulic fluid through a hydraulic circuit in the event of movement of an apparatus or platform from a stable to an unstable condition. Such platforms or apparatus may include for example, cranes, excavators, teletrucks and forklift trucks and roll over incidents of such machinery is common leading to numerous fatalities. Aspects of the present invention ensure fast switching in the event of a transfer from a stable to an unstable condition.

A control valve device includes a valve main body formed to have an actuator port connected to an actuator, a communication passage formed in the valve main body and configured to allow the actuator port to communicate with a drain port, and an on/off valve provided between the communication passage and the drain port, and the on/off valve includes a seat member assembled to the valve main body, an orifice provided in the seat member, and a poppet member configured to open and close a seat portion of the seat member.

The present invention relates to a hydraulic switch arrangement and a fluid switch for incorporating into a hydraulic switch arrangement that may be included in a hydraulic circuit for inhibiting flow of hydraulic fluid through a hydraulic circuit in the event of movement of an apparatus or platform from a stable to an unstable condition. Such platforms or apparatus may include for example, cranes, excavators, teletrucks and forklift trucks and roll over incidents of such machinery is common leading to numerous fatalities. Aspects of the present invention ensure fast switching in the event of a transfer from a stable to an unstable condition.

A hydraulic drive system includes an oil supply device, an oil return device and a hydraulic cylinder circuit component. The circuit component includes a hydraulic cylinder, a first and a second two-position two-way electromagnetic directional valves. The cylinder includes a first chamber and a second chamber that has a piston rod. A first port of the first valve connects with the first chamber and a first port of the second valve connects with the second chamber. When the oil supply device connects to a second port of the first valve and a second port of the second valve connects to the oil return device, the piston rod is extended outwards. When the oil supply device connects to the second port of the second valve and the second port of the first valve connects to the oil return device, the piston rod is retracted.