Bushing-restrictor

Claim 1

A fluid actuator comprising an actuator cylinder, a piston axially reciprocable in said cylinder, means for permitting fluid to flow into and out of opposite ends of said cylinder for reciprocating said piston, a rod projecting from said piston through a bore in one end of said cylinder, and a bushingrestrictor contained in said bore surrounding said rod, said bushing-restrictor comprising a sleeve having a plurality of axially spaced annular grooves in its outer periphery, the lands which define said grooves therebetween having a close sliding fit in said bore, and axial slots extending through said lands, said axial slots through adjacent ones of said lands being circumferentially offset from each other and of a size to permit a small portion of the fluid contained in the rod end of said cylinder to circulate through and around said grooves before discharging to the adjacent groove for cooling said rod end, the inner end of said sleeve having an outer diameter which is slightly less than the inner diameter of said bore to provide a slight diametral clearance which acts as an edge filter for permitting the fluid in the rod end of said cylinder to pass into the adjacent groove in said sleeve while restricting the passage of any large contaminants contained in the fluid, said sleeve having an additional groove adjacent said inner end which is slightly deeper than said plurality of axially spaced annular grooves for receiving the fluid passing through said diametrical clearance, said sleeve having still another groove adjacent the outer end of said sleeve which is axially longer than said plurality of axially spaced annular grooves, and radial holes extending through said sleeve communicating with said axially longer groove for lubricatIng said rod.