Extensible ladder

Details Extensible ladder Extensible ladder

1998-12-15

1999-07-27

Chin-Shue, Alvin

Fire escape, ladder, or scaffold

Wall- or floor-attached

Ladder

E06C 900

Patent

active

059274344

ABSTRACT:
An extensible ladder includes an upper frame, an up and down transmitting unit and a first and a second extensible frame. The first and the second extensible frame each have a plurality of pairs of crisscrossing rods pivotally connected with each other. Plural ladder steps and connecting rods are pivotally connected between the first and the second extensible frame. The connecting rods are pivotally connected to guide blocks, which have a vertical threaded hole for each of two threaded rods of the up and down transmitting unit to fit in and engage. Then each threaded rod has a clockwise threaded portion and counterclockwise threaded portion engaging the vertical threaded holes of the guide blocks. When an active rod with two worm sections is rotated by two worm gears combined with splines with an upper spline shaft portion of the two threaded rods, the active rod rotates the threaded rods, forcing the two extensible frames to extend down or shrink up.

REFERENCES:
patent: 209916 (1878-11-01), Ochsner
patent: 277124 (1883-05-01), Ferris

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