Spx Corporation

David A Dzioba

David L Anderson

A normally closed, three-way valve comprises a housing having a supply passage, a control passage, and an exhaust passage. A valve assembly controls communication between the passages. The valve assembly includes a valve in the supply passage to open and close communication between the supply and control passages. The valve assembly also includes a second valve in the exhaust passage to open and close communication between the control and exhaust passages. The supply passage valve is normally held closed by the pressure of hydraulic fluid in the supply passage. A solenoid, when activated, moves the exhaust passage valve to closed position. A pintle between the two valves is shifted in one direction by the closing of the exhaust passage valve to open the supply passage valve against the pressure of fluid in the supply passage. The pintle is shifted in the opposite direction by the supply passage valve when the solenoid is de-activated, to move the exhaust passage valve to its open position. A spring in the supply passage acts on the supply passage valve in the open position thereof and during an initial portion only of its movement toward the closed position to assist the fluid pressure in the supply passage in moving that valve to the closed position. The spring is loosely captured between the supply passage valve and a stop in the supply passage so that it does not act on the supply passage valve when it is closed. Hence, the supply passage valve is held closed solely by the pressure of fluid in the supply passage.

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Swartz Creek, MI, United States of America

David A Dzioba