Die spring construction

Abstract

A pneumatic shock absorber used primarily as a die spring includes a piston formed with a base and an upstanding cylindrical body provided with an internal fluid reservoir. An outer housing is mounted on the base and extends about the cylindrical body. An inner housing is axially telescopically mounted for sliding movements within the outer housing. A flexible sleeve is enclosed at one end by a sealing cap and is sealingly connected at its outer end to the exterior of the piston body forming a fluid chamber therein which communicates with the fluid reservoir of the piston. An opening is formed in the piston body to fill the reservoir and chamber with a high pressure fluid which places the inner housing in an expanded position by the end cap pressing against an end wall of the inner housing upon axial expansion of the sleeve. Rolled end flanges formed on the housings engage each other to stop the movement of the inner housing at the expanded position. The inner housing moves axially within the outer housing compressing the fluid trapped in the fluid reservoir and chamber to absorb axial forces applied to the piston and inner housing. A coating of low friction material is applied to the inner surface of the inner housing and to the outer surface of the piston body to reduce the sliding and rolling friction with the flexible sleeve during axial movement of the inner housing.