Hydraulic ram

US4457212A · kind A · utility

Assignee

• Gewerkschaft Eisenhutte Westfalia GmbH · DE

Inventors

• Eberhart Unger · Grafenau, DE
• Herbert Heitkamp · Werne, DE
• Heinz Hessel · Flaesheim, DE
• Karl-Heinz Plester · Grafenau, DE
• Manfred Lagodka · Grafenau, DE

Key dates

• Filing date: Apr 5, 1982
• Grant date: Jul 3, 1984
• Expiry date: Apr 5, 2002

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F16C11/06
• WIPO field: Civil engineering
• WIPO sector: Other fields

Abstract

A hydraulic ram for use in thrust-jacking of tunnel linings comprises a cylindrical outer member, a cylindrical inner member reciprocable within the outer member, and an extension member reciprocable within the inner member. A two-part clamping ring is provided for releasably locking the extension member to the inner member. An auxiliary drive is provided for retracting the extension member rapidly within the inner member. The auxiliary drive may be a mechanical spindle drive, or a hydraulic drive having an auxiliary piston reciprocable within an axial bore formed in the extension member. The clamping ring comprises spring means for urging the parts of the clamping ring in to the closed position, and piston-and-cylinder means for urging the parts of the clamping ring apart, against the biasing force of the spring means, to open the clamping ring.