Improvements in or relating to structures e.g. step ladders provided with wheels or other anti-friction devices

摘要

1,034,060. On and off castors. MARTIN THOMAS Ltd. May 18, 1965 [June 4, 1964], No. 23199/64. Heading A4U. [Also in Division A6] A steps or like structure, e.g. builders' staging, step ladders, trestles or platforms, is mounted on wheels 34, 39, castors or anti-friction balls and includes one such wheel 39 which is mounted for movement from its ground engaging position to a position clear of the ground when the steps or the like are loaded by a user's weight, the arrangement being such that when the wheel 39 is raised the non-slip feet 36, 37 engage the ground and remain in this position after removal of the user's weight. A tread member 41, 43, 44, 45 carries the raisable wheel 39 and is pivoted on a frame cross bar 42, one extended arm 44 of the tread being movable between fixed stops 59, 60 limiting the pivoting of the tread. The tread lever 44 forms a toggle with a telescopic link surrounded by a compression spring 55, the intermediate pivot axis 47 passing through a dead-centre position when the wheel 39 is raised or lowered so that the extended lever 44 is engaged with a snap action against one or other of the stops 59, 60. The wheel 39 may be re-set in its ground engaging position by foot pressure on the tread plate 41.