Method for forming a hydraulic cylinder assembly

A method of forming a hydraulic cylinder assembly utilizing a plastic material for the cylinder body. The method includes forming the cylinder body in a first molding operation and simultaneously molding one or more external walls on the exterior of the cylinder body having an axial thickness less than the axial thickness of the walls of the cylinder body and thereafter increasing the axial thickness of the exterior walls to a value substantially exceeding the thickness of the cylinder walls so as to define an appendage. Where the appendage includes a mounting flange, a small external annular wall is molded on the cylinder body during the initial molding operation having an axial thickness less than the thickness of the walls of the cylinder body and a larger flange is thereafter formed around the small flange. Where the appendage includes a reservoir, the external wall formed on the cylinder body in the initial molding operation includes an integral closed loop rim joined to the cylinder wall of the cylinder body by an annular wall having an axial thickness less than the thickness of the cylinder wall and the reservoir is thereafter provided by forming a reservoir around the rim. The steps may be performed in either order. Specifically, the reservoir or flange may be initially formed and then used as an insert in the mold cavity so that the cylinder main body, including the attaching rim or small wall portion, may be thereafter injected into the mold cavity in surrounding relation to the reservoir or flange insert.