| 摘要 |
388,378. Loft ladders. GORHAM, P. H., 5, King William Street, Greenwich, London. Aug. 21, 1931, No. 23559. [Class 20 (ii).] A collapsable loft ladder comprises lazy-tongs structures at the sides and back and is hinged to the lining of the trapdoor opening independently of the trapdoor, the latter being biased to the closed position and being arranged for movement to that position with the ladder upon it when the ladder is contracted. According to one construction, the ladder comprises side lazytongs 15, Fig. 4, and back lazytongs 9b, and is hinged to a bracket 33 fixed to the side 34 of the trap opening. The treads 7 are supported on brackets 16 attached to adjacent pivots of the lazy-tongs 15 on each side of the ladder. The centre pins of the lazy-tongs 9b are attached to cross-bars 8 which are connected at each end to the pins 35 of the side lazy-tongs. In a modified construction, each tread 7 is supported by a pair of bars 4, 6, Fig. 2, which extend across the width of the ladder and are connected respectively to the pins 3, 5 of the side lazy-tongs. The ladder is braced, when extended, by pairs of pivoted links 10, 11, which are connected to the side rails as shown and provided with stop pins 12 to limit their opening ; or, alternatively, are connected in a similar manner to the back lazy-tongs 9. To counterbalance the weight of the ladder, a cord 24, Fig. 6, is attached to the foot thereof and passes over a pulley 25 on a shaft 26, the counterweight being attached to a cord 28 which passes around a second pulley 27 on the shaft 26. To limit the extension of the ladder, a flat metal strip is threaded between the links of the side or back lazy-tongs, the strip being of sufficient width as to form an abutment for the pins connecting the links of the lazytongs. The trap door, in the form shown, comprises two hinged flaps 18, 19 which are interconnected by links 20, 21, 22. A weight 23 tends always to return the door to the closed position, in which position it is held by a latch 32. A rope passing around the shaft 26 may be utilized for raising or lowering the ladder. |
