GB1474086A - Coaster brake hub for a bicycle - Google Patents

Abstract

1474086 Coaster brake hubs SHIMANO INDUSTRIAL CO Ltd 30 May 1974 [31 May 1973] 24031/74 Heading B7E A coaster brake hub for a bicycle comprises a hub shell 1, a fixed member consisting of both a shaft 4 passing through the shell and a brake cone 7 fixed to one end of the shaft, a driving means 6 rotatably mounted on the shaft 4 at its end remote from the cone 7, a sprocket 10 fixed to the driving means 6, a clutch cone 11 screwthreadedly engaged with the driving means 6, a plurality of brake shoes 12 each having two tapered internal faces 12a, 12b engageable with outer tapered faces of the cones 11 and 7 respectively, and a helical spring 14 extending in the direction from the cone 11 towards the cone 7 and engaging the cone 11 and the fixed member. In operation rotation of the driving means 6 in the forward direction urges the cone 11 to the right as viewed in Fig. 1 by virtue of the screwthreaded connection between the cone 11 and means 6, thus causing the cone 11 to engage the shell 1 so that torque is transmitted to the shell from the means 6. Forward rotation of the means 6 and hence of the cone 11 also tends to wind up the spring 14 and radially contract it so that the spring does not resist rotation of the cone 11. However on commencement of reverse rotation of the driving means 6 and cone 11 the spring 14 tends to be unwound and hence is radially expanded so preventing further reverse rotation of the cone 11. Thereupon the reverse motion of the means 6 causes the cone 11 to be driven to the left as viewed in Fig. 1 by virtue of the screw-threaded connection, so forcing the brake shoes 12 into engagement with the hub shell 1. In the Fig. 1 embodiment the spring 14 is of opposite hand to the screw-thread on the driving means 6 and is engaged within bores in the cones 7 and 11. This embodiment may be modified (Fig. 3, not shown) by frictionally engaging the end of the spring adjacent the cone 7 around the shaft 4 or a sleeve fixed thereto, such that if reverse torque exceeds a predetermined value the spring is disengaged from the shaft or sleeve to prevent damage thereto. Alternatively, Fig. 4, the spring 14 may be of the same hand as the screw-thread and engage over a cylindrical extension 110 of the cone 11 and in a bore in the cone 7.