Abstract: The subject matter of this specification can be embodied in, among other things, a fluid actuator system including a fluid actuator having a housing having an inner wall defining an interior cavity, a piston having a piston head configured for reciprocal movement within the interior cavity, the piston head contacting the inner wall and dividing the interior cavity into a first fluid chamber and a second fluid chamber, a first valve configured to control fluid flow between the first fluid chamber and a bypass conduit, and a second valve configured to control fluid flow between the bypass conduit and the second fluid chamber.

Abstract: A pneumatic actuator air flow control system includes a pneumatic rotary actuator (PRA) and a solenoid air flow control valve (SAFCV). The PRA contains an air reservoir and a vane housing allowing pressurized air to rotate an air-driven vane. The SAFCV includes a flow control valve body (FCVB), a pilot solenoid valve (PSV) and a switch system, wherein the FCVB and the PRA can be connected to direct the pressurized air into the air reservoir, and the PSV is used to control the pressurized air in and out of the PRA to change the vane's rotation movement in the vane housing. Additionally, the switch system allows users to switch between a double-acting and fail-safe operation. When there is no pressurized air and/or electrical power and if an emergent need to open or close the valve, a manual override in the PSV can be used without further installation of a declutchable manual gear operator or external piping when there is no pressurized air and/or electrical power.

Abstract: A fail-safe fluid actuator comprising a piston slidably disposed within a cylinder. In the event of a pressure loss, the piston is urged to a fail-safe position by a plurality of externally mounted constant force spring mechanisms. In one embodiment the mechanisms are located at one end of the cylinder with a telescoping cover for protecting them from exposure and damage. In another embodiment the mechanisms are located at the side of the cylinder whereby the overall length of the actuator is significantly shortened. The fail-safe force applied to the piston by the spring mechanisms is externally adjustable, and they are readily accessible fur replacement or repair.

Abstract: A discharge valve is provided to open an electrically controlled pilot valve in emergency situations such as during an electrical or hydraulic failure. The discharge valve has a poppet that operates in response to a pressurized control signal, which may be produced by a hand operated pump. When the poppet opens in response to the control signal, a path is established for fluid to flow from a control chamber of the pilot valve, thereby opening the latter valve.

Abstract: The invention relates to safety device for a cylinder valve automatic switching unit, wherein said valve is automatically closed when some abnormality such as down of an air pressure takes place. A first air-operated selector valve 8 is installed which causes air flowing out of a reservoir tank 10 to flow into a second supply line 3 when air pressure is reduced, whereby a cylinder valve automatic switching unit 1 in the opening situation is caused to make a closing motion for closing a cylinder valve in the opened situation. And, a second air-operated selector valve 9 is further installed which discharges air flowing out of a first supply line 2 to the atmosphere when the air pressure is reduced.

Abstract: A fail-closed gas safety valve system for blast furnace stove operations employing two tight seal butterfly valves, one a gas shutoff valve and the other a gas regulating valve, which together operate to prevent the leakage of hazardous gas into a blast furnace stove area in the event the supply of air to the stove is interrupted because of a power or a hydraulic failure.

Abstract: A desired temperature within the passenger compartment (10) of a motor vehicle is selected by occupant movement of a control lever (80) for a variable resistor (VR2). The temperature of conditioning air being supplied to the compartment is measured by a thermister (72). The two temperatures are electronically compared. If the measured temperature is higher than the selected temperature, a solenoid (62) is energized which moves a control valve (48) in a position allowing passage of pressurized air into an air cylinder (26). The air cylinder (26) functions to close a valve (22) in a water line (18, 20) which extends from the engine cooling system to a heat exchanger (24) located within the conditioning air duct (12). When the temperature of the conditioning air falls below the selected temperature level, the solenoid (62) is de-energized and a spring (54) moves the control valve (58) into a position in which it blocks flow of compressed air to the air cylinder (26) and vents the air cylinder to the atmosphere.

Abstract: The present invention is directed to an improved fail-safe actuator and hydraulic system incorporating the same. The actuator includes energy storage means in the form of a spring adapted to set a control device in a predetermined condition, illustratively in the closed condition, responsive to a failure situation, illustratively, a power failure. The actuator includes a coupling which permits normal operation of the control device without cycling the spring energy storage means, thus increasing the life of the spring and eliminating energy wastage inherent in cocking the spring during each operative cycle.

Abstract: A self-restricting shutoff valve for use with a fluid leak detector to prnt excessive loss of fluid in event of a high flow-rate leak. A valve spool within a valve body is spring-biased to a partial flow position and is maintained in an opened position by fluid pressure. Upon loss of fluid system pressure, springs move the valve spool to a position to restrict fluid flow through the valve body. When sufficient loss of fluid occurs, a fluid leak detector actuates a pilot valve so that system fluid moves the valve spool to a closed position.