Patent ID: 6920819

Claim:
A piston and seal assembly comprising: a cylindrical piston ( 14 ) for being slidably mounted within a cylinder and having an annular groove ( 24 ) in the outer circumference thereof, said groove ( 24 ) defined by upper ( 26 ) and lower side ( 28 ) walls spaced apart by a bottom ( 30 ) and extending into the outer circumference of the piston ( 14 ), said upper side wall ( 26 ) having a greater depth than the depth of said lower side wall ( 28 ) so tat said bottom defines a frustoconical shape about said piston ( 14 ), and a piston ring ( 22 ) having a frustoconical cross-sectional shape disposed in said groove and including outer and inner annular surfaces that are spaced apart and parallel with an outer end extending between said annular surfaces and an inner end extending between said annular surfaces.