Cylinder end cap

Claim 1

A cylinder end cap comprising: a. a one-piece metal end plate adapted to form the end of a cylinder, said end plate having first and second opposed surfaces and having a hole therein extending between said surfaces for a piston rod of specified diameter, said hole having a central portion of diameter larger than said specified diameter and being substantially enlarged at each end, each end of said hole being defined by a steeply outwardly sloping beveled edge surface, b. a sleeve of a urea-urethane elastomer that is resilient, tough and resistant to creep and set under load, said sleeve being molded in place in said hole and extending between said first and second surfaces and thus overlying said beveled edge surfaces, said sleeve having an outer surface bonded over substantially its entire length to said end plate, the adhesion of said sleeve to both said edge surfaces reducing the likelihood of said sleeve being stripped from said end plate, c. said sleeve having an interior aperture for said piston rod, said interior aperture being, over its middle portion, of diameter slightly greater than that of said piston rod, d. said sleeve including adjacent one end thereof a first lip extending slightly into said interior aperture to form a wiper and including adjacent its other end a second lip extending slightly into said interior aperture to form a seal and bearing for said piston rod, said lips defining interior openings of diameter slightly less than that of said piston rod, e. said urea-urethane elastomer having a Bashore rebound elasticity of between about 30 percent and 50 percent, a hardness of between about 95 Shore A and 55 Shore D, an A.S.T.M. Die C resistance to tearing value of at least 500 pounds per inch, and an elongation at break of at least 400 percent, f. said end plate including means for connecting said end plate to said cylinder.