GB190206767A - A New or Improved Free Wheel and Variable Speed Gearing for use in connection with Velocipedes, Motor Cars and the like and for other purposes. - Google Patents

Abstract

6767. Braithwaite, J. H. March 20. Driving-mechanism; clutches.-Relates to freewheel gearing by which the speed ratio may be continuously varied between an upper and a lower limit. In the application to a bicycle, shown in Figs. 1, 2, 3, and 10, the hub a, Figs. 2 and 3, is formed or fitted with a disc a having slots a' formed in thickened portions a<3> of the disc. Pins c, fitted with friction rollers to slide in the slots a<2>, are secured to clutches c arranged in an annular groove b<1> in the chain-wheel b, which has a supporting-flange b<2> and is mounted in ball bearings b<3> on a disc d mounted free to slide vertically on a sleeve d<1> mounted in ball bearings on the hub. The disc d is formed with an elongated opening d<3> having flanged edges, which engage with shoulders on the sleeve d', a portion of one edge being detachable to allow the disc d to be placed in position. A pin f secured to the sleeve d<1> and passing through the flange on the disc d prevents the sleeve d<1> from rotating. The sleeve d is supported by a forked rod g, Fig. 1, sliding in a tube g<2> secured to the back stays, and is pressed downwards by a spring h. It is raised into any desired position with respect to the flange a by means of a cord passing over a pulley on the frame and attached at its end, as shown in Fig. 15, to a block i<1> sliding in a spiral groove j formed in the boss of a lever j<3> pivoted on the top bar. The clutch blocks c may be fitted with roller clutches c<2>, Fig. 10, and be supported by balls c<3>, or they may carry pawls which engage with ratchet teeth cut in the side or bottom of the groove b<1>. As only the clutch which is moving fastest can engage the groove b<1> at one time, it follows that the speed ratio increases with the eccentricity of the wheel b and hub a<1>. Fig. 19 shows means for automatically lowering the speed ratio when the tension of the chain is increased. The slot d<2> is horizontal, the disc d being secured to a rod k pressed rearwards by a spring n, which is overcome when the tension of the chain increases. Sudden changes of tension are rendered inoperative by a piston p secured to the rod k, sliding in a cylinder o secured to the forks, and fitted with a valve and a small hole, which allow oil contained in the cylinder to pass forwards freely, but retard its rearward motion.