GB191317236A - An Improvement in the Propelling-mechanism of Bicycles and the like. - Google Patents

Abstract

17,236. Boyd, A. July 28. [Cognate Application, 28,957/13.] Cranks, variable-throw. - In pedal - crank driving - mechanism for cycles, of the kind wherein the pedal is elongated and connected to the crank-pin by a one-way clutch, an additional spindle or member freely supported by the crank-pin is provided, and this member, connected to the pedal by the one-way clutch, is geared to the crank bracket in such a way that its angular velocity is reduced below that of the crank-pin either continuously throughout the revolution of the crank or only at such time as it is desirable for the pedal to be ankled for effecting the clutch connexion. The gearing may comprise chain or toothed-wheel gearing connecting a spindle rotatably mounted in a hollow crank-pin to a fixed wheel on the crank bracket, or the bracket and spindle may carry equal toothed-wheels, the ratchet-wheel of the clutch being freely mounted upon the fixed pin and arranged to carry planet-wheels in mesh with a sun-wheel on the pin and with internal teeth on a flanged disk carried by the spindle. As shown in Figs. 7 and 8<a>, the pedal d is connected by a dog clutch n<1> with a ratchetwheel c<1> engaged by pawls upon a plate m; this plate has a pin m<1> passing through a slot in the boss of the crank a and engaging the rod l of a strap upon an eccentric k rigidly or adjustably fixed to the bottom bracket. Or the rod l may be connected to a crank-pin on a wheel at the pedal instead of using the plate m. In order to safeguard the pedal from injury should it contact an obstacle when the machine is being wheeled, the pedal is arranged to be disconnectible from the ratchet mechanism. A two-armed lever o, p, Fig. 9, has a boss q with a projection engaging a recess s in a bearing r, a bolt u mounted freely in the boss being forced outwardly to engage one of a set of holes in a pawl-carrying disk c<1> by a spring v when either lever o or p is depressed by the rider's foot. As soon as pressure is removed from the lever it is pressed back by a spring t and raised by the action of the recess s, and the boss q bearing upon a nut at the end of the bolt carries the bolt out of engagement with the disk c<1>. According to Provisional Specification 28,957/13 more than one disengaging arrangement may be fitted to each pedal.