extendable ladder od.dgl. for use on a vehicle is obvious

摘要

1287467 Ladders E W FAULSTICH 13 Nov 1969 [28 Nov 1968] 55686/69 Heading E1S [Also in Division B8] An extendable boom or ladder has a support 24 which is operated in conjunction with the extension of the upper boom or ladder section 20 so that said section is simultaneously raised and extended. In the preferred embodiment the ladder section 20 is raised by a cable 36 driven by an electric motor 30, to which cable is attached the section 20 and also the top 26 of the support the attachment points being on opposite sides of the pulley 38 on the lower section 18 around which the cable passes. Clips 50, 52 on the cable engage the ends of springs 54, 56 attached to limit switches which reverse the direction in which the cable is driven by the motor, (Figs. 6-8, not shown). The support 24 is moved clockwise (with respect to the configuration of Fig. 5) when the section 20 is extended, and anticlockwise when it is retracted.