Patent ID: 6053286
Filing Date: 2000-04-25
Classification: B66B

Abstract:
A lift system, comprising:a. a first rail extending parallel to a stairway step nose angle and mounted to a vertical support;b. a frame being movable along said first rail;c. a first roller set for engaging opposite sides of said first rail;d. a first coupling means for coupling said first roller set to said frame;e. a first pressing means for pressing said first roller set against said first rail to create sufficient traction contact area between said first roller set and said first rail to support the weight of said frame;f. a second rail extending along and mounted to the vertical support and parallel to said first rail at a constant vertical gauge;g. a second roller set for engaging opposite sides of said second rail;h. a second coupling means for coupling said second roller set to said frame;i. a second pressing means for pressing said second roller set against said second rail to create sufficient traction contact area between said second roller set and said second rail, and also to support the weight of said frame;j. a drive means respectively coupled to said first and second roller sets for driving said frame in either direction; andk. each of said pressing means including a spring means that directly engages the respective roller set at a direction perpendicular to the respective rail, each of said pressing means further including a traction adjustment bolt connected to an internal plate which is slidably located within a pair of interlocking tubes for allowing the internal plate to be adjusted to compress said spring means and providing additional traction pressure.