GB232280A - An improved variable speed gear - Google Patents

Abstract

232,280. Biggs, C. E. Nov. 14, 1923. Variable-speed and reversing gearing comprising a set of worms 7 - - 10, Fig. 2, slidable on a driving-shaft 20 and adapted to be enmeshed alternatively with a nest of driven worm-wheels 11 - - 14 is operated by a single rod 4 which turns and also slides. The shaft 20 is supported in a bracket 17<1> supported on a pair of toggle links 18 articulated to shoes 19 which latter normally lodge in transverse slots 21 in a fixed frame 22. In gear position, this bracket 17<1> is locked by pins 17 projecting through holes in a laterallyslidable plate 15 which carries the worm-wheels. As shown in Fig. 1, the worm-wheels 11 - - 14 slide together on a differential sleeve 1 and the nest as a whole drives forwardly through a pawl 32 and rearwardly through a pawl 33. When the speed is to be changed, a main driving clutch is disengaged and the rod 4 is turned so that arms 5 upon it through links 6 withdraw the shoes 19 from the grooves 21. At the same time the bracket 17' falls and the pins 17 are disengaged. The rod 4 is then thrust longitudinally carrying with it the bracket and set of worms, the shoes 19 sliding in a long groove. This longitudinal movement through a bell-crank 23, Fig. 3, moves the plate 15 and nest of worm-wheels transversely. When the proper worm is under its worm-wheel, a turning back of the rod 4 straightens up the toggles 18 and holds the worm gearing firmly in mesh. The pitch of the worm 7 for reversing is of opposite hand to the others.