Patent GB-444570-A (GB)
Title: Improvements in and relating to automatic change-speed gearing
IPC: F16H61/02
Filed: 1934-08-23
Abstract: 444,570. Variable-speed epicyclic gearing; automatic clutches; yielding-shaft couplings. EDWARDS, A. W., Te-Aroha, Compstall Road, Romiley, Cheshire. Aug. 23, 1934, No. 24302. [Class 80 (ii)] Change-speed gearing suitable for motor-cars is rendered automatic bv a resilient torque coupling B, Fig. 3, which acts ' through two different auxiliary stepped - planetary trains 46, 54, Fig. 1, which effect a relative angular displacement of a toothed quadrant 50, Fig. 4, which is rotating all the time. The coupling B has a step-bystep action and the quadrant 50 is turned in steps to change between low, middle, and high speeds in an epicyclic transmission with triple planets 12, 15, 67, Fig. 1. In the arrangement shown, the torque coupling B has centrifugal weights 33, 34, so that it is responsive in part to the speed of the driven shaft 21 as well as to the torque load on that shaft. There is a separate reversing-gear R operated by a hand lever 79 and an automatic engine clutch A. The clutch A comprises weights 3, Fig. 2, normally held by springs 6 near the trailing ends of the weights pressed inwards against a flange 2b of a disc 2, Fig. 1, carried by the engine shaft 1. Links 4 connecting the weights 3 to the disc 2 are set at such an angle that when the clutch is driving, they help to hold the weight 3 against an outer flange 8 forming the driven member of the clutch. The angle of the links 4, further, is such that the flange 8 cannot drive back to the disc 2, giving a free-wheeling effect. The planet gear 12 meshes with a sun gear 9a on a clutch shaft 9 which carries the engine clutch drum 8 and a gear clutch drum 10. The planet gear 15 meshes with a gear 16 which is the driven element of the train and is rigid with a middle shaft 43 between which and the driven shaft 21 the torque coupling B is set. The planet gear 67 meshes with a sun ring 68 which is prevented from turning backwards by a oneway brake 70. A carrier frame 13 of the planets 12, 15, 67 carries also an expanding brake 58, shown also in Fig. 4, and a precisely similar expanding clutch 30. When the load is too light to collapse a spring 19, Fig. 3, the transmission turns solid in high speed because the clutch 30 is expanded into engagement with the drum 10. When the load increases, the spring 19 collapses and cups 31, 32 which support its ends come together and the driven shaft 21 turns back relatively to the shaft 43 by a distinct step. A rod 44 squared to turn with the shaft 21 passes through the shaft 43 and carries a sun gear 53 of an auxiliary train alongside a sun gear 45 on the shaft 43. Stepped planets 46, 54 carried by one and the same loose carrier 47 mesh respectively also with a sun gear 49 connected to the sector 50 and with a sun gear 56 fast to the carrier 13 of the main gear train. The step yield in the coupling B causes a relative turn between the gears 53, 45 and this is passed on by the trains 46, 54 as a relative turn between the gears 49, 56, which means that the toothed sector 50, Fig. 4, turns so as to rock a cam shaft 52. This rocking applies the brake 58 to a fixed ring 66 and at the same time contracts the clutch 30. The carrier 13 is thus held against rotation and the train 9<a>, 12, 15, 16 acts to bring in middle speed. If the load increases so as to collapse also a stronger spring 17, Fig. 3, another stepped relative displacement is passed along to the cam shaft 52 causing it to contract and withdraw the brake 58. The sun gear ring 68 is now immobilized by the one-way brake 70 and the planets revolve so as to drive the gear 16 and shafts 43, 21 at low speed. A snap action of the torque coupling or governor which prevents hunting is obtained thus. The torque coupling shown in Fig. 3 connects a driving crank-arm 39, Fig. 9, on the shaft 43 to a driven crank-arm 20 on the shaft 21. Between these two crank arms is a loose member 18, Fig. 7, having rigid cross-arms 18<1> and 18<2>. The cross arm 18<2> supports rockably cups 31, 31<1>, Fig. 3, supporting ends of the torque springs 19, 17 the other ends of which are in cups 32, 32<1> secured by studs 39<1>, 20<1> respectively to lateral extensions of the arms 39, 20. In the position shown in Figs. 3 and 9, the weights 33, 34, which are pivoted at 41, 42, hold bowls 35, 36 hard against cams 37, 38 on the arms 39, 20 so that the drive passes from the arm 39 to the arm 20 through the cross - arm 18<1>, Fig. 7, without stressing the torque springs. When, however, the bowls 35, 36, snap off the arms 39, 20, the drive passes through both springs 19, 17 in series, and first one of these collapses, and then the other, to yield the snap-action three-position automatic speed control.