Patent ID: 6899014
Filing Date: 2005-05-31
Classification: F15B

Abstract:
1. A telescopic multi-stage hydraulic hoist, comprising: an outer stage tube having one end sealed by a base member and an open end, and having a wall formed from an aluminum alloy from one of the series 2000,6000 or 7000 aluminum alloys; at least one additional tube stage disposed within the open end of said outer stage tube such that there is an overlap between said tube stages, said at least one additional tube stage having a wall formed from a heat treated aluminum alloy; a hydraulic fluid port in communication with an interior of the tube stages; and at least one seal mounted between tube stages, whereby forcing hydraulic fluid into said hydraulic fluid port causes said at least one additional tube stage to extend relative to said outer tube stage; whereby the walls of said tube stages have a modulus of elasticity which allows the tube stages to expand under the force of a momentary pressure spike, and upon release of the pressure spike, to retract to their original configuration.