Cantilever brake with quick release mechanism

A cantilever brake of bicycle is provided with a triangular cable stop including first, second and third corner attachments and a wheel between the first and second corner attachments; a first pivot member including a first trough; a first cable passing through the first corner attachment, the wheel, and the second corner attachment to be fastened at the first pivot; a second pivot member including a second trough; a second cable having one end fastened in the third corner attachment and the other end fastened in the second pivot member; a first brake arm releasably pivotably secured to the first trough and including two opposite first projections and a spring actuated first adjustment knob distal the first projections; and a second brake arm releasably pivotably secured to the second trough and including two opposite second projections and a spring actuated second adjustment knob distal the second projections.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to bicycle brakes and more particularly to a cantilever brake having a quick release mechanism.

2. Description of Related Art

A conventional cantilever brake of bicycle comprises two outwardly-angled arms protruding on both sides respectively, a cable stop on the frame to terminate a cable housing, and a straddle cable between the arms. In a braking operation, a rider may press a brake lever against a grip to pull upwards on the straddle cable, causing the brake arms to rotate up and inward thus squeezing the rim between the brake pads.

However, a number of drawbacks have been found in the conventional cantilever brake. In detail, arrangement for separating a cable stop from either brake arm is not provided. Thus, cable may be drawn into the spokes when the cable is broken. This can cause danger to a rider. Moreover, no elastic force adjuster provided two brake arms. Its adaptability is very poor. Thus, the need for improvement still exists.

SUMMARY OF THE INVENTION

It is therefore one object of the invention to provide a brake device of bicycle comprising a triangular cable stop comprising a first corner attachment, a second corner attachment, a third corner attachment, and a wheel disposed between the first and second corner attachments; a first pivot member comprising a first trough; a first cable passing through the first corner attachment, the wheel, and the second corner attachment to be fastened at the first pivot; a second pivot member comprising a second trough; a second cable having one end fastened in the third corner attachment and the other end fastened in the second pivot member; a first brake arm releasably pivotably secured to the first trough of the first pivot member and comprising two opposite first projections and a spring actuated first adjustment knob distal the first projections; and a second brake arm releasably pivotably secured to the second trough of the second pivot member and comprising two opposite second projections and a spring actuated second adjustment knob distal the second projections.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 1 to 7, a cantilever brake1of bicycle in accordance with the invention comprises the following components as discussed in detail below.

A triangular cable stop2comprises a first corner attachment21, a second corner attachment22, a third corner attachment23, and a wheel24provided between the first and second corner attachments21and22. A first cable W1coming from a housing (not shown) near a brake lever (not shown) passes through the first corner attachment21, the wheel24, and the second corner attachment22before leaving. The provision of the wheel24can reduce friction caused by braking force exerted on the first cable W1, i.e., facilitating brake.

A first pivot member3is shaped as a hook and comprises a first trough31defined by two joining portions. The first cable W1has one end fastened in the first pivot member3. Similarly, a second pivot member4is shaped as a hook and comprises a second trough41defined by two joining portions. A second cable W2has one end fastened in the third corner attachment23and the other end fastened in the second pivot member4.

A metal sleeve7is put on a section of the first cable W1from the second corner attachment22to one end of the first pivot member3distal the first trough31.

A first brake arm5is releasably pivotably secured to the first trough31of the first pivot member3(seeFIG. 5). The first brake arm5comprises two opposite first projections53proximate the pivot point, a first adjustment knob52disposed in a position distal the first projections53, and a first torsion spring52having one end rotatably secured to an attachment (not numbered) and the other end secured to the first adjustment knob52.

Similarly, a second brake arm6is releasably pivotably secured to the second trough41of the second pivot member4(seeFIG. 4). The second brake arm6comprises two opposite second projections63proximate the pivot point, a second adjustment knob62disposed in a position distal the second projections63, and a second torsion spring62having one end rotatably secured to an attachment (not numbered) and the other end secured to the second adjustment knob62.

It is envisaged by the invention that an individual may rotate the first adjustment knob52to adjust elastic force of the first torsion spring52and similarly rotate the second adjustment knob62to adjust elastic force of the second torsion spring62.

As shown inFIGS. 3 and 6, in response to the first cable W1being broken when riding, the first pivot member3pivots counterclockwise until contacting the first projections53(i.e., being stopped by the first projections53). This can prevent the first cable W1from being tangled with the wheel8. Further, both the first pivot member3and the first brake arm5are pushed outward by the lowering sleeve7(i.e., a section of the first cable W1) and both the second pivot member4and the second brake arm6are pushed outward by the lowering second cable W2. This also can prevent the first pivot member3, the first brake arm5, the second pivot member4, and the second brake arm6from contacting the wheel8. As a result, driving safety is greatly improved.

As shown inFIGS. 3 and 7, in response to the second cable W2being broken when riding, the second pivot member4pivots clockwise until contacting the second projections63(i.e., being stopped by the second projections63). This can prevent the second cable W2from being tangled with the wheel8. Further, both the first pivot member3and the first brake arm5are pushed outward by the lowering sleeve7(i.e., a section of the first cable W1) and both the second pivot member4and the second brake arm6are pushed outward by the lowering second cable W2. This also can prevent the first pivot member3, the first brake arm5, the second pivot member4, and the second brake arm6from contacting the wheel8. As a result, driving safety is greatly improved.