GB385112A - Variable-speed transmission gearing - Google Patents

Abstract

385,112. Variable-speed gearing. ALVIS CAR & ENGINEERING CO., Ltd. and CLARKE, G. T. SMITH-, Holyhead Road, Coventry. Dec. 22, 1931, Nos. 35366/31, 22614/32, and 29104/32. [Class 80 (ii).] Variable-speed gearing comprises an hydraulic coupling in combination with an epicyclic toothed train and a mechanical clutch in parallel with the coupling so that the latter cushions engagement of the former. When used with conventional change gearing in place of the usual engine clutch on a vehicle, the mechanical clutch is disengaged in changing speed. The engine shaft 4, Fig. 1, carries the driving member 2 of the hydraulic coupling which has a casing extension 2<1> secured to a female clutch cone 19. The male clutch member 18 is splined at 17 on a sleeve 12 fast to the sun gear 11 of the epicyclic train. The driven member 5 of the coupling is fast to the annulus 6 of the train and to a plate 13 closing a recess containing the train. Planet gears 7 are carried directly on the driven transmission shaft 8. The male clutch member 18 is doubly coned and is normally held in firm double engagement by springs 22 acting on a female cone 20 splined at 21 to the casing 2<1>. In this position, with the engine throttled down, the coupling members rotate idly in opposite directions. The cone 20 is connected by a sleeve to a thrust ring 23 outside the casing to which a rightward manual thrust is applied to compress the springs 22 and withdraw the cone 20 from clutch engagement. At the same time, a Belleville spring 24 automatically thrusts the male cone 18 clear of the cone 19, freeing the driven coupling member 5 from mechanical constraint. A form is described with a single spring-pressed clutch cone having an angle of 28‹ to ensure firm gripping engagement. In a form shown in Fig. 2, the male clutch cone 18a is rendered self-tightening by mounting it on a quick-pitch thread 28 on a sleeve 27 splined at 17 on the sleeve 12 of the sun gear 11. The sleeve 27 is held against axial motion by a flange 34 which forms an abutment for clutch-engaging springs 41. The springs 41 act on a collar 35 which engages projections 31 on keys 30 sliding in straight grooves 29 in the sleeve 27. The keys 30 have inclined lands 32 engaging the clutch cone 18a so that the springs 41 turn the cone 18a which screws into firm. engagement with the member 19 and casing 21. Disengagement is effected by a pedal leftward thrust on a block 39 which slides the collar 35 and keys 30 so as to unscrew the nut cone 18a sufficiently. A bevel planetary train may be used.