Band Brake Assembly for Bicycle

1. Field of the Invention

This invention relates to a band brake assembly for a bicycle including a brake lining of a brake band adapted to be urged against an outer circumferential surface of a drum to obtain braking force.

2. Description of the Prior Art

In a prior art band brake assembly for a bicycle as shown in FIG. 1, when an inner wire a of a brake operating cable is tensioned for operating the brake assembly, the tensile force is transmitted through a bell crank b to a brake band d integral with a lining c so that a frictional force caused between a drum e and the lining c is supported through a fixed end f of the brake band d by a casing g.

In this manner, when the operating end of the brake band c is directly subjected to a force through the bell crank b by the inner wire a, vibration caused between the lining c and the drum e is transmitted to the casing g to give rise to a resonance phenomenon. In other words, as only the tensile force acts over the entire length of the brake band d, it is likely to go into vibration which in turn causes resonance of the associated parts resulting in discomfort noise.

It is therefore a general object of the invention to provide an improved band brake assembly for a bicycle, which eliminates the above disadvantage of the prior art by a particular arrangement absorbing vibration generated in a brake band for preventing discomfort noise in braking.

In order to achieve the above object, the band brake assembly for a bicycle including a brake band having a brake lining to be urged to a brake drum by brake operating force acting on a brake operating cable in braking, according to the invention comprises a wire guide consisting of a front half and a rear half, said front half being in the form of an arc and fixed to an operative end of said brake band, said rear half extending in a tangential direction of said brake band, and an inner wire of said brake operating cable, said inner wire extending rearward along an outer surface of said wire guide and being fixed to a rear end of said wire guide.

The invention will be more fully understood by referring to the following detailed specification and claims taken in connection with the appended drawings.

FIG. 1 is a front elevation of a band brake assembly partially in section of the prior art;

FIG. 2 is a front elevation of a band brake assembly partially in section according to the invention;

FIG. 3 is a plan view, partially in section taken along lines III--III in FIG. 2, illustrating the assembly shown in FIG. 2;

FIG. 4 is a partial sectional view of the assembly shown in FIG. 2;

FIG. 5 is a sectional view taken along the line V--V in FIG. 4; and

FIG. 6 is an exploded perspective view of the assembly of FIGS. 2 and 3.

A preferred embodiment of a band brake assembly according to the invention shown in FIGS. 2-6 comprises a brake hub 2 fixed to a frame 1 by means of nuts 3, and a brake drum 4 threadedly engaged with a threaded portion of the brake hub 2 and fixed to the brake hub 2. In this embodiment, a casing 5 enclosing the brake drum 4 is fitted on the brake hub 2 and a torque arm 6 extending in front of the frame 1 is fixed to the frame by means of a bolt 7 engaging a deep notch 6a of the torque arm 6.

A fixed end 9a of a brake band 9 provided with a lining 8 fixed to its inner surface is fixed through a spacer 11 to the casing 5 by means of a rivet 10. A wire guide 12 consists of a front half 12a and a rear half 12b having a channel-shaped cross-section as shown in FIG. 5. The front half 12a is formed in an arc along an outer circumference of the brake band 9 and is fixed onto an outer surface of an operative end 9b of the brake band 9. The rear half 12b extends in a tangential direction of the brake band 9. A wire adjuster 14 is fixed to one end of an outer wire 13 of a brake operating cable and is also fixed to the casing 5 by means of a nut 15. An inner wire 16 of the brake operating cable extends rearward along the channel of the wire guide 12 and fixed to the wire guide 12 at its rear end by means of a bolt 17 and a nut 18. The casing 5 is formed with an opening 5a through which the rear half 12b of the wire guide 12 extends as shown in FIG. 2.

The band brake assembly constructed as above described according to the invention operates in the following manner. With this arrangement according to the invention as shown in detail in FIGS. 4 and 5, the front half 12a of the wire guide 12 is fixed onto the outer surface of the operative end 9b of the brake band 9 and the inner wire 16 extends on the bottom of the channel of the wire guide 12 and is fixed to the rear end of the wire guide 12 which extends away from the drum 4 in its tangential direction at an appropriate location thereon. Accordingly, the four members, i.e. the lining 8, brake band 9, wire guide 12 and inner wire 16 are overlapped to form a multiple or overlapped connection which is more advantageous than the prior art in view of prevention of vibration due to friction. In other words, when braking, the brake band 9 and the inner wire 16 are subjected to tensile forces and the wire guide 12 therebetween is subjected to a compressive force, so that these overlapped members are slightly shifted relative to each other to prevent the resonance and to absorb and damp the vibration.

In the illustrated embodiment of the invention, the casing 5 of the brake assembly is fitted on the hub 2 and fixed to the frame 1 by means of the bolt 7 which passes through the deep notch 6a of the torque arm 6 extending from the casing 5, thereby enabling the casing 5 to be simply and securely attached to the frame 1.

While the invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details can be made therein without departing from the spirit and scope of the invention.