摘要 |
A loft ladder of the captively sliding type is adapted to be fully automatic by the provision of a power unit (5) in the form of a reversible type of electric motor driving a gear assembly, incorporating a non-reversible worm and wheel, which in turn drives a drum or pair of drums around which a nylon cord (3) is wrapped. This nylon cord 3, by means of pulleys 5, is the medium through which the ladder 1, is lowered and raised. Accurate and critical placing of these pulleys 5, ensure a smooth transition from the angle of the ladder 1, when in use, to the horizontal position in the loft when stored. A three way spring loaded switch, controls the motor unit which automatically shuts off via a micro-switch 12, at the completion of trap 4, closure. <IMAGE> |