Valve seat

In a throttle valve comprising a valve housing having an annular recess therein, a throttle member pivotally movable in the valve housing and having an annular seal face throttle member seal face, the improvement comprising said valve seat including resilient means located in said annular recess and defining an annular groove, and a radially movable seat ring located in said annular groove, said seat ring being made of a stiff material but with sufficient radial direction resiliency such that when subject to a radial load from contact with the throttle member seal face said seat ring may be displaced and/or deformed in the radial direction, said resilient means and said seat ring cooperating so that when said ring moves in a radial direction under said radial load said resilient means sealingly engages said seat ring and when said radial load is removed from said seat ring said resilient means maintains said seat ring substantially in the displaced shape and position, so that wear between said seat ring and said seal face is minimized in that when said seat ring is circular and said seal face is circular, the seat ring is displaceable into alignment with said seal face and is maintained in the aligned position when said radial load is removed therefrom, and when said seat ring is circular and said seal face is elliptical, said seat ring is deformed into an elliptical shape and is maintained in said elliptical shape when said load is removed therefrom.