GB452162A - Improvements in and relating to variable speed transmission mechanism - Google Patents

Abstract

452,162. Variable - speed gearing. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London. April 9, 1935, No. 11004. Convention date, April 10, 1934. [Class 80 (ii)] Expansible toothed gear - wheels comprise toothed segments 7, guided in radial slots 12 and spiral slots 11, in discs 10, 9 respectively, the discs being turned relatively to each other automatically by the torque of the drive, opposed by a helical torsion spring 13, which latter tends to open out the segments to their maximum effective diameter. The scroll-disc 9 is secured to the driving shaft 4. The segments 7 are guided by segmental pieces 14, arranged between the discs 9, 10 and having projections 15, 16 engaging the slots 12, the segments 7 having pins 8 passing through the pieces 14 into the slots 11. Internal springs 20 press on flats 21 of the pins 8 to hold the segments normally in a radial position, from which they can yield slightly to obtain correct mesh. A double arrangement is used, an expanding-wheel on the driving shaft 4, meshing inside an internally toothed wheel 23 on an eccentrically-adjustable countershaft 24, carrying a second expanding-wheel, meshing inside an internally toothed wheel 30 on the driven shaft 5. The countershaft 24 is pivotally carried by a swinging arm 25, loaded by a helical torsion spring 28 to preserve mesh. The torque-loading spring 13a of the second expanding-wheel is of greater strength than that of the first wheel, to balance the greater torque which it transmits.