Hydraulic lash adjuster

Claim 1

An hydraulic lash adjuster comprising a hollow cylindrical body member having a bottom wall at one end thereof, a hollow plunger member having a bottom wall at one end thereof and an upper wall at the upper end thereof slidably disposed within said body member, said plunger and said body member defining a pressure chamber between the bottom walls thereof, said plunger member having a reservoir chamber therein and an aperture in said bottom wall thereof, check valve means operatively associated with said aperture to permit fluid contained in said reservoir chamber to pass through said aperture to said pressure chamber while preventing fluid flow in the opposite direction, clearance means between said body member and said plunger member and passage means through said plunger means communicating said clearance means with said reservoir chamber, spring means located in said pressure chamber for biasing said plunger member away from the bottom wall of said body member and a structurally independent, free floating member disposed on and substantially covering the upper surface of said hydraulic fluid in spaced relation to said upper wall of said reservoir to prevent air above the fluid from being absorbed by the fluid in operation.