Bosch develops ABS for the front wheel of motorcycles

In Asian cities, traffic is dominated by two wheels and, unlike the protection that a car can provide, in the event of an accident the risk of injury for motorcyclists is much higher. For this reason, Bosch has developed a specific anti-lock braking system for the low-cost motorcycles and scooters popular in this region. The technology is based on the Generation 9 brake control system for motorcycles, but features only one hydraulic brake channel, which controls the front wheel. “The new front wheel ABS offers a significant safety improvement at a reduced cost” said Gerhard Steiger, President of the Chassis Systems Control division. “ABS can significantly reduce the number of injuries and deaths caused by road accidents”. Known as ABS 9M light, this system is currently being developed at the Bosch center for motorcycle safety in Japan, in collaboration with an Indian motorcycle manufacturer. Series production is planned for 2013.

When a motorcycle wheel locks, a potentially dangerous situation arises. In the event of a locked rear wheel, the brake release reaction to unlock it is more timely than in the same circumstance with the front wheel, where the slightest delay makes the driver's fall from the vehicle inevitable. Weight shifts forward during braking, so deceleration is done primarily through the front wheel. This explains why in many Asian countries even the rear wheels of motorcycles with an engine displacement of 250 cc or more are braked by a mechanical cable brake. “Adjusting the braking pressure on the hydraulically braked front wheel prevents locking and allows maximum deceleration to be achieved, considerably increasing stability” said Wolfgang Hiller, Regional President of Bosch Chassis Systems Control Division in Japan.

At the base is a generation of high-performance ABS

The new ABS 9M light is an economical entry-level version of the Bosch generation 9 brake control system for motorcycles. The hydraulic unit includes two control valves, a tank and a pump. The reference speed of the wheels is calculated by the system based on information from a sensor located in the front wheel. To ensure the greatest possible stability during braking, the specific reference speed of the wheel is continuously adapted to the actual speed of the vehicle. More precise braking control would be possible if a second sensor was installed on the rear wheel. With this configuration, the deceleration speed corresponds to that of the basic 2-channel system, counteracting any lifting of the rear wheel. At the discretion of motorcycle manufacturers there is the possibility of integrating an on and off switch.

The software of the new front ABS has been optimized for the low-power segment. For larger and more powerful motorcycles, Bosch offers basic ABS and ABS plus systems, which control both wheels and offer additional optional functions. The top of the range is represented by the enhanced ABS system which integrates the eCBS combined electronic braking function on both wheels, even if the driver brakes on only one.