GB474070A - Improvements in or relating to gradual action change speed gears - Google Patents

Abstract

474,070. Variable-speed gears. BOYER, M. Jan. 22, 1936, Nos. 2103 and 2104. Void. Convention dates, Jan. 22, 1935 and May 29, 1935. [Class 80 (ii)] A variable-speed gear device comprises an adjustable eccentric driving member A, Fig. 1, driven from a shaft O which is adapted when displaced eccentrically with respect to the shaft O to impart an oscillatory movement to a ring C rotatably supported thereon and to which are pivotally connected rods B<1>, B2 having at their extremities uni-directional connections with two rings R<1> and R<2> respectively. If one of these rings R<1> is fixed, a reaction is obtained by means of which the oscillatory movement of the ring C and rods B<1> and B<2> can impart a forward motion to the other ring R<2>, the value of which depends upon the amount of eccentricity of the driving member A. Alternatively, if R<2> is held, the ring R<1> can be driven in the reverse direction. The driving thrust on the rods B<1> and B<2> always tends to reduce the eccentricity of the member A and if this thrust is opposed by a spring D tending to increase the eccentricity a speed of the driven member R<2> which varies automatically with the driving load is obtained. Figs. 3 and 4 show a practical embodiment of the invention, the ring R<1> being held by the gear casing, the ring R<2> secured to a driving shaft F and the eccentric A being adjustable on a driving shaft E by means of gearing 6, 7, the pinion 6 being actuated by a quick-pitch thread engagement with an axially-slidable sleeve 21. This sleeve is controlled by a lever 26 which is actuated either by hand as required or by an external spring D to give an automatic speed-variation with the load. Alternatively, the gear may be controlled automatically, through a relay or directly, by a governor, float, or any other variable factor. The connecting rods B<1>, B2 engage the rings R<1>, R<2> through pivoted toothed segments 9 which are guided in annular grooves 14 in the rings and drive in one direction only. Other oneway driving devices such as wedging balls or rollers may be used and the rods B<1>, B<2> may drive through one-way devices pinions geared to the rings R<1>, R<2>. Alternatively, a one-way driving device may be provided on one ring only, a pivotal connection being provided on the other and a sliding pivotal connection on the eccentric. In a modified arrangement, Fig. 8, the gear is adapted for use on a bicycle, and in this arrangement the eccentric A does not rotate but is adjustable on another fixed eccentric 8. The ring R<1> serves as a driving wheel, being connected to the pedal crank 17, and the wheel R<2> is driven and carries the chain wheel 33. In this case a speed multiplication is obtained which can be varied manually as required or automatically by adjustment of the eccentric 8. In another modification, the eccentric member A is stationary and the ring C is driven positively on the eccentric by the driving shaft through a coupling of the Oldham type. In this case, single rods B<2> with one-way devices only are utilized acting on a single driven ring R<2>, the reaction ring R<1> and rods B<1> being dispensed with. Two or more of the speed reducing or multiplying devices may be arranged in series to give a wider range of speed variation. By arranging two automatically variable-speed devices as shown in Fig. 1 in parallel, with a common drive member for the two driving eccentrics, a dual drive can be obtained off two driven rings R<2>, which arrangement fulfils the function of a differential gear.