GB685058A - Improvements in extending ladders - Google Patents

Abstract

685,058. Loft ladders. GRAVITY LADDERS, Ltd. Feb. 12, 1951 [Nov. 11, 1949; June 19, 1950]. Nos. 28924/49 and 15232/50. Class 20 (ii). In a loft ladder of the sliding extension type, an outwardly directed flange 27, Fig. 4 on each rear stringer 26 of one ladder section 10 slidably engages between a pair of spaced inwardly directed flanges 30, 31 on the front stringer 29 of the other ladder section 11. The front and rear stringers 29, 28 on each side of the section 11 are spaced apart to form a longtitudinal slot 41 Fig. 5 engaged by rollers 38, 39 on a runner 37 pivotally and adjustably mounted in one of a series of holes 40 on a bracket 47 secured to the top face of the trap door 15 Fig. 2. A similar arrangement slidably secures the ladder section 11 to brackets 12 secured to the loft floor 13 adjacent the opening. Radius arms 17 are pivotally secured near the top of the section 11 and to brackets 18 on the loft floor to control angular movement of the ladder during lowering, torsion springs 20 Fig. 6 (not shown) fitted around pivot pins 19 on the brackets 18 serving to oppose the lowering movement of the ladder. Adjustable stops 43 Fig. 2 on the section 11 limit its downward movement by abutting against the brackets 12 and a similar arrangement ensures that the ladder section 10 is extended to a position to bring the treads of the overlapping steps level. The stringers which may be extruded, rolled or drawn sections of light aluminium alloy, are secured to the front and rear flanges 23, 24, Fig. 4 of grooved or corrugated channel section steps 21., Instead of the unitary stringer member 29, two similar overlapping L-section members may be secured together to form the stringer. According to the first Provisional Specification instead of the rollers 38, 39, Fig. 5, the slots 41 are engaged by brass sliders pivoted on bracket pins provided with adjustable spring controlled friction washers for resisting motion of the ladder relatively to the pins.