Patent ID: 7178787

Claim:
A valve assembly comprising: a valve member having a valve stem extending from a head end portion of said valve member, said valve stem having reference surface and a valve stem thread convolution; a valve seat disposed in engagement with said head end portion of said valve member; a primary spring which extends along said valve stem; and a spring retainer having a spring retainer thread convolution which engages said valve stem thread convolution on said valve stem, said primary spring being compressed between said valve seat and said spring retainer to provide a primary spring preload force which presses said valve seat against said head end portion of said valve member, said spring retainer thread convolution on said spring retainer and said valve stem thread convolution on said valve stem transmit force to press a force transmitting surface on said spring retainer against said reference surface on said valve stem with a retainer preload force which is at least as great as said primary spring preload force; a circular damping disk disposed between said primary spring and said spring retainer, said damping disk having a circular outer side surface which cooperates with a housing to dampen movement of said valve member relative to the housing, and a plurality of circular shims disposed between said primary spring and said damping disk, each of said shims having a circular outer side surface with a diameter which is less than a diameter of said circular outer side surface of said damping disk.