| 摘要 |
333,595. Bessler Disappearing Stairway Co., (Assignees of Bessler, F. E.). Jan. 19, 1929, [Convention date]. Ladders.-An attic ladder of the type which is power-actuated and is caused to swing as it slides through a ceiling opening, has the driving means controlled automatically by the movements of the swinging element. The ladder 13 is adapted to slide on brackets 14 pivotally mounted on a drum shaft 15, which is driven through reduction gearing from a motor 22. The motor is controlled through two hand switches 24, 25, and an automatic stopping and connection re-setting switch 26, which is operated by movements of the radius arms 16, which are pivoted to the switch box and to the upper ends of the ladder. A lug 16<a>, Fig. 3, on a radius arm operates switch arms 27, 28 connected to a lug plate 30, which is caused to actuate a tumbler 29 through pins 29<a> at the two extreme positions of the ladder. In order to render the control adjustable, contact screws 31 are used in the switch arms. An automatic switch for controlling a light in the upper room may be actuated through the other radius arm, and in order to foil burglars, or to keep out intruders when the ladder is raised, a cut-out switch 32 may be placed in the upper hand switch 25. In a modification, Fig. 6, for use with lofty rooms, the main ladder is provided with a sliding extension 35 operated from a separate drum 35<a> on the drum shaft, and the motor 22 is placed at the other end of the ceiling opening, part of the reduction gearing being at the motor end and part at the drum-shaft end. In a further modification, the ladder is raised and lowered by pinion and rack gear 40. 41 driven through worm gearing from a vertical shaft 23<c> operated by the motor 22, which is placed in a wall recess in the lower room, and in this form a ladder extension operated by belt and pulley gearing may also be provided. The lower end of the stairway is provided with a panel 18 to act as a ceiling closure. Specification 216,692 is referred to. |
