GB594408A - Improvements in or relating to power transmission mechanism - Google Patents

Abstract

594,408. Variable-speed gearing. HOBBS, H. F. Sept. 30, 1944, No. 18756. [Class 80 (ii)] Variable-speed gearing comprises a driving shaft 10, at least one layshaft 50, two intermediate shafts 12, 13 between which power can bE distributed in at least two ratios, gears on the intermediate shafts 12, 13, and on a driven shaft 11, meshing with gears on the layshaft or layshafts, and a double dog clutch 56 movable in opposite directions to bring two powei paths into operation, a third power path being also provided which is made effective when the double dog clutch 56 is in a neutral position. As shown, for a gearing providing seven forward speed. ratios, the shafts 12, 13, have bevel gears 23, 24, engaging planets carried by a spider 22. Clutch plates 26, 27, on the spider 22 and gear 23, respectively, are clutchable to a housing 34 driven by the shaft 10. Gears 15, 17, fixed on the shafts 13, 12, engage gears 16, 18, fixed on layshafts 50, 53, which also have gears 20, 25, engaging loose and fixed gears 19, 21, on the driven shaft 11. Layshaft 53 is loose on layshaft 50 but can be clutched thereto by a dog clutch 68 actuated by a yoke 74. The double dog clutch 56 is splined to the driven shaft 11 and in its extreme positions clutches to either shaft 12 or gear 19. The clutch 56 is moved by a yoke 64 which is linked to the yoke 74 so that the clutch 68 can be engaged only when the member 56 is in the neutral position shown. The clutches 26, 27, are actuated, when desired, by fluid pressure generated by a pump 45. The dog clutches have baulking rings 65, 66, 71, to ensure synchronous engagement. The gearing has four separate power paths of different ratios through which power can be transmitted separately or through pairs of paths simultaneously viz:-(a) 12, 56, 11; (b) 12, 17, 18, 53, 20, 19, 56, 11; (c) 13, 15, 16, 50, 25, 21, 11; and (d) 12, 17, 18, 68, 50, 25, 21, 11. The seven forward ratios are (1) Through path (b) clutches 27 and 19-56 being engaged and 26 disengaged; (2) through paths (b) and (c) simultaneously, clutches 26 and 19-56 being engaged and 27 disengaged; (3) through path (d) with clutches 27 and 68 engaged and 26, 19-56 disengaged; (4) through paths (c) and (d) simultaneously with clutches 26, 68 engaged and 27, 19-56 disengaged; (5) direct drive through path (a) clutches 27, 12-56 being engaged and 26 disengaged; (6) overdrive through paths (a) and (c) simultaneously with clutches 26 and 12-56 engaged; and 27 disengaged, and (7) overdrive through path (c) clutches 26, 27, being both engaged and all dog clutches disengaged. The layshafts instead of being concentric may be offset from each other or arranged end to end. In a modification which is also described in Specification 590,607 means are provided for a reverse speed. Specifications 549,988 and 560,379 also are referred to.