Abstract: A fluid flow control device has an inlet, an outlet and an exhaust port all for an operating fluid. A pilot inlet receives a pilot pressure signal which operates a valve stem actuator via a piston. The valve stem is operable to open a supply valve between the inlet and outlet and, to open an exhaust valve disposed between the outlet and the exhaust. In a further position both the valves are closed. A first fluid leak path is provided between the valve stem and the supply valve for allowing fluid to leak through the supply valve chamber when the supply valve is open and a second fluid leak path is defined by the exhaust valve for allowing fluid to leak through the exhaust valve chamber. The leak paths provide for a force balancing arrangement. A quick exhaust feature allows exhaust flow through the device.

Abstract: A fluid flow control device has an inlet, an outlet and an exhaust port all for an operating fluid. A pilot inlet receives a pilot pressure signal which operates a valve stem actuator via a piston. The valve stem is operable to open a supply valve between the inlet and outlet and, to open an exhaust valve disposed between the outlet and the exhaust. In a further position both the valves are closed. A first fluid leak path is provided between the valve stem and the supply valve for allowing fluid to leak through the supply valve chamber when the supply valve is open and a second fluid leak path is defined by the exhaust valve for allowing fluid to leak through the exhaust valve chamber. The leak paths provide for a force balancing arrangement. A quick exhaust feature allows exhaust flow through the device.

Abstract: A fluid flow control device has an inlet, an outlet and an exhaust port all for an operating fluid. A pilot inlet receives a pilot pressure signal which operates a valve stem actuator via a piston. The valve stem is operable to open a supply valve between the inlet and outlet and, to open an exhaust valve disposed between the outlet and the exhaust. In a further position both the valves are closed. A first fluid leak path is provided between the valve stem and the supply valve for allowing fluid to leak through the supply valve chamber when the supply valve is open and a second fluid leak path is defined by the exhaust valve for allowing fluid to leak through the exhaust valve chamber. The leak paths provide for a force balancing arrangement. A quick exhaust feature allows exhaust flow through the device.

Abstract: A main control valve is actuated by a pilot fluid control signal between open and closed positions to supply fluid to an actuator such as a valve actuator. A stack of logic control valves is supported on the main valve- and controls the flow of the pilot signal. Each of the logic control valves has a housing of common design. Intermediate flow-directing plates of different designs provide fluid communication between adjacent housings. The stack has a common pilot feed passage and a common exhaust passage that are each defined by an annular clearance around supporting tie bars that pass through bores in the stack. Each plate has apertures that form part of the exhaust and pilot feed passages and an aperture that interconnects the returning pilot signal with the pilot inlet of the next valve in the stack. The arrangement allows for simplification of the design of the apparatus with a single housing design and multiple plate designs.

Abstract: A fluid flow control device such as a volume booster has an inlet, an outlet and an exhaust port all for an operating fluid. A pilot inlet receives a pilot pressure signal which operates a valve stem actuator via a diaphragm assembly. The valve stem is operable to open a supply valve between the inlet and outlet and, separately and independently, to open an exhaust valve disposed between the outlet and the exhaust. In a further position both the valves are closed. Movement of the stem in a reciprocal manner by the diaphragm assembly causes a respective annular shoulder to engage a respective valve and lift it off a valve seat against the force of a biasing spring. A first fluid leak path is provided between the valve stem and the supply valve for allowing fluid to leak through the supply valve chamber when the supply valve is open and a second fluid leak path is defined by the exhaust valve for allowing fluid to leak through the exhaust valve chamber.

Abstract: A main control valve is actuated by a pilot fluid control signal between open and closed positions to supply fluid to an actuator such as a valve actuator. A stack of logic control valves is supported on the main valve- and controls the flow of the pilot signal. Each of the logic control valves has a housing of common design. Intermediate flow-directing plates of different designs provide fluid communication between adjacent housings. The stack has a common pilot feed passage and a common exhaust passage that are each defined by an annular clearance around supporting tie bars that pass through bores in the stack. Each plate has apertures that form part of the exhaust and pilot feed passages and an aperture that interconnects the returning pilot signal with the pilot inlet of the next valve in the stack. The arrangement allows for simplification of the design of the apparatus with a single housing design and multiple plate designs.

Abstract: A fluid flow control device such as a volume booster has an inlet, an outlet and an exhaust port all for an operating fluid. A pilot inlet receives a pilot pressure signal which operates a valve stem actuator via a piston. The valve stem is operable to open a supply valve between the inlet and outlet and, separately and independently, to open an exhaust valve disposed between the outlet and the exhaust. In a further position both the valves are closed. Movement of the stem in a reciprocal manner by the piston causes a respective annular shoulder to engage a respective valve and lift it off a valve seat against the force of a biasing spring. A first fluid leak path is provided between the valve stem and the supply valve for allowing fluid to leak through the supply valve chamber when the supply valve is open and a second fluid leak path is defined by the exhaust valve for allowing fluid to leak through the exhaust valve chamber.

Abstract: A fluid flow control device such as a volume booster has an inlet, an outlet and an exhaust port all for an operating fluid. A pilot inlet receives a pilot pressure signal which operates a valve stem actuator via a diaphragm assembly. The valve stem is operable to open a supply valve between the inlet and outlet and, separately and independently, to open an exhaust valve disposed between the outlet and the exhaust. In a further position both the valves are closed. Movement of the stem in a reciprocal manner by the diaphragm assembly causes a respective annular shoulder to engage a respective valve and lift it off a valve seat against the force of a biasing spring. A first fluid leak path is provided between the valve stem and the supply valve for allowing fluid to leak through the supply valve chamber when the supply valve is open and a second fluid leak path is defined by the exhaust valve for allowing fluid to leak through the exhaust valve chamber.