GB407384A - Improvements relating to change speed gears - Google Patents

Abstract

407,384. Controlling variable speed gearing. GESSNER, E. A., 4, Wettinerstrasse, Erzgebirge Aue, Germany. Aug. 18, 1932, No. 23226. [A Specification was laid open to inspection under Sect. 91 of the Acts, Aug. 19, 1932.] [Class 80 (ii).] In epicyclic variable-speed gearing, reaction drums are held against rotation to bring driving ratios into effect by positive detents, which, by allowing drums to freewheel in one direction, allow the driven shaft of the whole device to overrun, and a vehicle to coast. In Figs. 21 and 22 the invention is shown applied to the multiple-train bevel toothed gearing of Fig. 5 of Specification 370,090. Reaction drums 81, 82, 83, which are to be held selectively against rotation, are provided with rings of peripheral ratchet teeth 95. Each ring of ratchet teeth is adapted to be engaged by its own spring pawl or plunger 96 which slides radially in a fixed casing 57. The pawls 96 are held out of action against their springs 98 by an axially slidable cam bar 100. When the bar 100 is moved as by a pedal 101 so as to bring a cam recess 103 under a bowl 99 carried by a selected pawl, that pawl 96 is pressed by its spring into engagement with the ratchet teeth to hold the selected drum against rotation in one direction. The pawl for reversed driving is directed oppositely to the pawls for forward drives. Additional means may be provided for holding the drums positively against rotation in both directions. Each drum 81, 82, 83 has a peripheral ring of castellated teeth 89 adapted to be engaged for this purpose by a similarlytoothed dog member 92 sliding in a groove 93 in the casing 57 and operable from a pull rod 94. Band brakes may be provided in addition for slowing down the drums prior to positive stoppage. In Fig. 1 is shown an arrangement in which two sliding cam bars 147, 148 are adapted to operate selectively spring pawls 141 which engage ratchet teeth 140 on drums 130 &c. associated with stepped spur planetary gears 125 &c. In Fig. 13 is shown the application of the invention to the planetary roller variable-speed gear of Fig. 1 of the Specification referred to. A friction disc 19 is the reaction member and this has to be held against rotation in one direction or the other according to the radial position of the rollers 10. There are therefore two oppositely-acting pawls 41, 42 which are operated selectively by a manual control bar 45. A brake band is shown at 44. At 38 is shown a gear wheel rigid with the reaction drum adapted to be driven from an additional source of power to increase the range of speeds of the ultimately-driven shaft 15.