Combined Brake System for small motorcycles has been developed.
In small motorcycles, some models have a hydraulic disc brake both in the front and rear wheels but many of them have a hydraulic disc front brake and a mechanical drum rear brake. Accordingly, it was necessary to develop a new system to link the hydraulic system with the mechanical system to allow an application of Combined Brake System to these models.
In this paper, a CBS having a new configuration is described where a disc brake and a drum brake are linked in a simple lever structure of an input force distributor, and an inhibitor spring at the foot pedal. With this mechanism equipped, the distribution of brake forces is controlled. When a large input force is applied, a large proportion of brake force is applied to the front brake to obtain adequate deceleration. When a mild input force is applied, which is frequently operated, the brake force proportion is large in the rear compared to the front. Thus, the motion of nose dive is reduced and a strange feeling to a rider is alleviated. Those characteristics of brake force were produced by a lever arm ratio of the distributor and a pre-applied load to the inhibitor spring. The implementation of this system made it possible to apply an advanced brake system to small motorcycles with reasonable prices.