Laterally retractable frame for staircase - comprises half steps with two rungs rotating on central mounting raised on stringers where they are retracted, plates at rung ends form hinge receiving spindles on which rungs rotate

摘要

The retractable staircase comprises half steps each with two rungs (6) rotating on a central mounting raised on wooden stringers where they are retracted. The U sectioned stringer is formed from a thin web (1) connecting the sides (2). The central H section mounting is also formed by a web connecting the two sides. Plates (3,4) fixed at the ends of the rungs form a hinge which receive the spindles (7) on which they rotate. From one side the spindle extensions penetrate into drillings (8) in the sides of the stringers and the central mounting. From the other side their heads are supported in a notch (10) in the web of a corner piece (9). The force for raising the rungs is reduced by a flexible brake arm fixed on the rear of one of the stringers.