GB397242A - Variable speed gearing - Google Patents

Abstract

397,242. Variable-speed gearing. KIMBER, W. G., 195, Pear Tree Avenue, Bitterne, Southampton. Feb. 21, 1933, No. 10556/32. [Class 80 (ii).] Continuouslyvariable toothed gearing comprises pivoted toothed segments 5, Figs. 1 and 3, which revolve and come into engagement in succession with a toothed wheel 6, the segments 5 being biased against an adjustable cam 10 by springs 26. The segments 5 are supported on studs 4 on a disc 3 fast on a driving shaft 1. The wheel 6 is fast on a driven shaft 7 offset with respect to the shaft 1. Each segment has a roller 25 which rolls round the periphery of the cam 10 which is turned about a fixed pivot 11, Fig. 5, to assume more or less eccentric positions and, by varying the swing of the segments, to control the speed of the driven shaft 7. As the disc 3 turns clockwise of Fig. 3, a segment at D comes into mesh with the wheel 6. As it passes to position E, it imparts a clockwise drive which is sustained elastically by the spring 26. The drive is direct when the cam 10 is concentric as shown in full lines in Fig. 5. As a lever 14 is turned to the left, the cam 10 is moved to eccentric positions on the right and the speed is reduced until it falls to zero with the lever 14 in position A and the cam as shown in chain lines A<1>. The lever 14 acts to annul the effect of a spring 19 which acts on a freely-pivoted lever 18 so as to balance the load reaction on the cam 10 which pushes the cam 10 towards lower-speed positions. The gearing when controlled by the spring 19 alone varies automatically with the load. The leftward displacement of the manual lever 14 asserts itself by acting on the balance lever 18 against the spring 19 by a finger 16 on the former engaging a lug 17 on the latter. The springs 26 allow of freewheeling on forward drives. To effect reversed driving, the lever 14 is moved further to position B, so raising a segmental cam 22 turning on a fixed pivot 23, which cam takes the reaction of the rollers 25. The cam 22 reinforces the springs 26 in turning the segments 5 clockwise to Fig. 3 about their pivots 4 to impart an anticlockwise drive to the wheel 6. The toothed segments may have their teeth directed outwardly instead of inwardly.