GB614332A - Improved change speed gear for bicycles and like vehicles - Google Patents

Abstract

614,332. Change-speed gear. KLEFFENS, . E. J. VAN. Dec. 28, 1945, No. 35045. Convention date, Aug. 29, 1942. [Class 80 (ii)] In a bicycle crank-shaft counter-shaft changespeed gear controlled by backwards movement of the crank-shaft 2, in which the gears or sprockets 3, 4, 5 are couplable to the driving shaft 2 through internal free-wheel clutches having pawls 16 and equal-spaced ratchet teeth, the gears are so constructed that one revolution of one produces, through the counter-shaft 11 and its gears 8, 9, 10, one revolution plus or minus a whole number of pitches of the ratchet teeth of the other gears on the driving shaft. Adaption for use with a back-pedalling brake is obtained by pawls 17 engaging the ratchet teeth of one of the gear-wheels under the action of the spring 22, these pawls are fixed to a shaft 19 forming part of an interrupting device having a feeler 13 which moves in contact with a disc 14 provided with recesses which allow the pawls 17 to be moved into the operative position only when the pedal cranks are substantially horizontal. The pawls 16 for the normal direction of rotation are pressed into the operative position by springs 21 and are also inter-coupled by a locking shaft 23 having a groove engageable with a tooth on the pawls and so arranged that when one pawl enters the operative position its tooth rotates the locking shaft through a predetermined angle to lock the remaining driving pawls in the inoperative position until the operative pawl is again urged into the inoperative position. In a modification, the driving pawls are held in unstable equilibrium between the operative and inoperative positions and are connected either mechanically (Fig. 16), hydraulically, or pneumatically so that when one pawl is moved from the unstable to the operative position, the force on the remaining pawls is decreased to allow them to enter the inoperative position. A further modification provides a two-speed gear in which the braking is effected in low speed and a locking shaft is arranged to be controlled by the interrupter so that the braking pawl is locked in the inoperative position so long as the high-speed pawl is in the operative position and conversely. Detail modifications to the pawls, their controlling means and the spacing of the ratchet teeth are also described.