Patent ID: 8820703

Claim:
A fluid flow valve comprising: a body member having flow ports interconnected by a flow orifice surrounded by an annular planar valve seat normal to an operating axis; a stepped piston counterbore in said body member spaced from and coaxial with said valve seat, said piston counterbore having an open end and a closed end, wherein the stepped piston counterbore has a first portion having a first diameter and a second portion having a second diameter greater than the first diameter; a valve guide sealing said open end of piston counterbore and having an opening therethrough coaxial with said operating axis; a stepped piston slidably supported in said piston counterbore coaxial with said operating axis, said piston forming a first chamber between said piston and said closed end of said piston counterbore and a second chamber between said piston and said valve guide, wherein the stepped piston has a first portion having a first diameter and a second portion having a second diameter greater than the first diameter, and at least a portion of the first portion of the stepped piston is received in the first portion of the stepped piston counterbore and the second portion of the stepped piston is received in the second portion of the stepped piston counterbore; and a poppet valve member having a stem extending through said opening in said valve guide and coaxially operatively connected to said piston for concurrent movement between an open position and a closed position, said poppet valve member having an enlarged head section having a sealing surface normal to said operating axis for engaging said valve seat in said closed position at a sealing interface.