Pushbutton activated water pressure balanced mixing valve

A hydraulically activated water pressure balanced mixing valve for use in faucets and shower/tub discharge controls including a valve sleeve having hot and cold water inlets and a mixed water discharge, a chamber within said valve sleeve, a valve member movably positioned within said chamber, said valve member having a hot water passage communicable with said sleeve hot water inlet and said sleeve mixed water discharge, and a cold water passage communicable with said sleeve cold water inlet and said sleeve mixed water discharge,

• a housing, said sleeve and valve member being positioned within said housing, an outlet in said housing connected to said sleeve mixed water discharge,
• generally equal pressure balancing surfaces on said valve member, passage means in said housing connected to said sleeve mixed water discharge and to each of said pressure balancing surfaces for applying water pressure onto said surfaces for causing water temperature modulation movement of said valve member within said sleeve, with such movement changing the relative communication between said sleeve hot and cold water inlets, mixed water discharge and said valve member passages,
• a passage connecting each of said pressure balancing surfaces with said housing outlet, and manually operable check valves in each passage connecting a pressure balancing surface and said housing outlet, operation of one of said check valves reducing the water pressure applied to one of said pressure balancing surfaces causing the valve member to move thereby changing the extent of communication of each of the sleeve hot and cold water inlets with the sleeve mixed water discharge to vary the water temperature thereof.