Telescopic differential column hydraulic cylinder

Claim 1

A hydraulic cylinder capable of withstanding cantiliver loading, said cylinder including a first elongated support member including large and small outside cross-sectional area end portions, a second cylinder member including large and small inside cross-sectional area end portions sealingly and slidingly engaged with said first support member large and small end portions, respectively, defining a peripheral expansion chamber between said support member and said cylinder member, means operative to admit and evacuate fluid under pressure to and from said expansion chamber, said large and small end portions of said second cylinder member defining large and small outside cross-sectional area end portions, and a third cylinder member including a large cross-sectional area base end and a small cross-sectional area far end sealingly and slidingly engaged, respectively, with said large and small end portions of said second cylinder member and defining a peripheral expansion zone between said second cylinder member and said third cylinder member between said base and far ends, means establishing communication between said chamber zone, the end of said small diameter end portion of said support member remote from the large diameter end portion thereof including an abutment thereon against which the small diameter end portion of said second cylinder member may abut to limit movement of said second cylinder member away from said large end portion of said support member, said small diameter end portion of said second cylinder member including an abutment thereon against which said far end of said third cylinder member may abut, and abutment means operative to limit movement of said second and third cylinders relative to and toward the large end portions of said support and second cylinders members, respectively.