GB797885A - Improvements in or relating to extensible ladders - Google Patents

Abstract

797,885. Extending ladders. MILES, Ltd., A. Aug. 23, 1954 [Aug. 21, 1953], No. 23069/53. Class 20(2) An extensible ladder comprises an erecting stand 15 in the form of a guide with which a plurality of similar ladder sections may be engaged one after the other, the stand 15 having winding gear operable to project the first ladder section 10 from the stand and there to retain it whilst the next succeeding ladder section 11 is engaged with the stand 15 and is projected by the winding gear to cause it to engage endwise with the first ladder section 10 by plug and socket connections after which further operation of the winding gear effects further projection of the ladder sections in the form of a continuous ladder. The stand 15 consists of a pair of channels 16 connected together at their lower ends by a shoe 18, with their open sides facing each other and with adjustable struts 19 pivoted to their upper ends and connected to their lower ends by the rods 20. Rounds 17 are secured to the back webs of the channels 16 to constitute the lowermost part of the ladder and the major portion of the front webs of the channels 20 are cut away to enable one of the ladder sections to be engaged therewith. The winding gear consists of an endless chain 24 passing over an upper sprocket 22 and a lower sprocket 23 having an operating handle 25, the chain carrying a series of hooks 26 which engage the rounds 27 of a ladder section positioned in the stand 15. At the upper end of the stand a manually releasable gravity or spring loaded pawl 28 engages a round of a projected ladder section to retain that section in projected position. Each of the sockets 14, Fig. 5, at the lower ends of the strings of the ladder sections contain a blade spring 35 which engages a shoulder 32 on the plug 13 at the upper end of the next lower ladder section whereby the sections are automatically locked together. To allow automatic release of this locking means when the winding gear is operated to lower the ladder sections, the socket 14 is provided with a release catch 36 which, is operated by a ramp 40 in the inner surface of each channel 16 of the stand 15.