since 1989 and continually improved since, these lightweight double-acting cylinders bolt rigidly to the rack housing with four symmetrically located sockets head cap screws. The thrust is absorbed independently of the bolts by a 9/16 dowel. A thick nonmetallic piston prevents metal-to-metal contact in the bore and contributes to the very long useful life of these parts. These cylinders are tested to 1800 PSI in both directions