GB1323741A - Ladder - Google Patents

Abstract

1323741 Folding ladder; lockable hinges H HOFFMANN W HOFFMANN and H BRENNENSTUHL 29 July 1970 [30 July 1969 14 Feb 1970] 36750/70 Headings E1S and E2F Folding ladder sections 10, 18, e.g. are pivoted together by means allowing locking of the section in different relative positions. In the embodiment of Figs. 1-4 joint fittings 11, 17 are attached to the section, each fitting comprising one or, as shown, two spaced discs e.g. 12, 12a, there being a releasing lever 21, also comprising spaced plates, pivotally mounted on one disc 26. The lever 21 is pivoted from the Fig. 1 position in the direction of arrow. 28 to push a channel-sectioned spring loaded stop pin 20 out of engagement with one of peripheral apertures 13-15. The lever is then held by cams 63, 63a engaging notch 61' in lever. When ladder sections are now relatively rotated the spring loaded pivot pins 56', 57' are pushed in by dimples 60'a, to force lever plates inwards and thus disengage cams 63, 63a from notch 61'. The lever now allows the pin 20 to enter the next aperture. In the embodiment of Figs. 5, 6, the stop pin 33 is loaded eccentrically, and a further pin 64, engaging a hole 61 is used in place of cams 63, 63a as an arresting device. In the embodiment of Figs. 7-10, the lever 80 is spring- loaded by a spring 81 into the positions corresponding to an engaged position of a stop pin 86 with one of peripheral apertures 72-74 and the position corresponding to a disengaged position of the stop pin. The pin 86 can move in a slot 87 in joint fitting 75, and in an aperture 88 in the lever. With the lever rotated lockwise to a position corresponding to a disengaged position of pin 86, the ladder can be folded, but on unfolding, cams 94-96 engage a shoulder (99) on lever 80 and cause it to rotate until pin 86 is engaged in one of the apertures. The pin can now only be released manually via the lever.