Patent GB-674529-A (GB)
Title: An improved gear for greatly varying speed and output
IPC: F16H15/24
Filed: 1950-02-22
Abstract: 674,529. Variable-speed friction gearing; epicyclic gearing. HACKER, O. Feb. 22, 1950, No. 4535/50. Class 80 (ii). A variable - speed friction gear comprises two pairs of inter-engaging friction members. One pair,. Figs. 2 and 3, consists of a roller 3 on a driving shaft 2 engaging with the rubber lining 4a of a drum 4, which has its position altered to change the gear ratio, while the other pair comprises a roller 6, integral with a hollow shaft 5 and drum 4, engaging the rubber lining 7a of a drum 7 on a driven shaft 9. The shape of the drums and the working of the gear are designed to obtain correct correlative rolling between the rollers and drums, and to ensure that the number of load changes forced upon the friction lining, depending upon the frequency of revolution of the drums, is inversely proportional to the pressure of the rollers on the drums. The adjustable friction parts 4 and 6 are housed in a sleeve 12 connected by its flange 12a and pivot 13 with a ring 14 connected to levers 23; the levers are supported at one end by a pressing roller 26, arranged In knee-levers 28 pivoted in the gear case, and at the other have mounted in them a pressing roller 25 resting on pressing levers 30. Draw-springs 32 connected to the knee-levers 28 at 27 and to the pressing levers 30 at 33 force the pressing roller 26 against the rims 23a of the adjusting levers 23. The rims 23a have the same shape as the generatrix of the cone 4, along which the movable friction parts are shifted to change the gear ratio. The pressure exerted upon the levers 23 by the roller 26 remains constant, while the springs 32 press the levers 30, pivoted at 31 in the gear case, against the roller 25 of the adjusting levers 23, with a pressure varying and depending on the position of the friction parts; as the gear ratio increases, so the pressure exerted upon the roller 25 by the rims 30a increases. The pressing roller 26 remains stationary, while the other pressing roller 25 moves with the secondary roller, 6, so that the points of contact of the pressure rollers with their respective adjusting levers follow the movements of the points of contact between the members 3, 4 and 6, 7 as the gear ratio is changed. The arm 12a of the sleeve 12 carries a pivot 15 with an adjusting rod 16, which at 17 is connected with a shifter lever 19 by which the gear ratio is changed. The bracket 20, supporting the horizontal axle 18 of the shifter lever, is movable around the vertical axle 21, when the shifter lever swings vertically in relation to the plane of the paper. This movement is transmitted via the sleeve 12 to the drum, the shaft and roller 4-6, which accordingly undergoes a crosswise lateral displacement to facilitate the process of changing speed. When this occurs, a spiral movement of the rollers within the drums takes place. After every complete change the shifter lever jumps into the groove of a medium position when the main axis 11 and the axle of the movable friction parts lie in the same plane. In a modification, Fig. 1, the change of speed is caused by moving the drum 4 and roller 6 in relation to the driving shaft 2 by means of a carrier 35. In this form, a differential gear 36 is connected with the driving shaft 2, a differential gear 37 being connected with the output shaft 34 of the variable speed gear by means of the reversing wheels 38, 39, 40. The power is carried off by the planet wheels 41, the pinion cross 42 and the driven shaft 43. By suitable selection of the gear ratio between, the wheels 40 and 38 the arrangement can be so adjusted that the output shaft rotates from zero either in one or both directions as the variable speed gear is operated.