Bosch ABS anti-lock braking system

What it is

Bosch ABS is an anti-lock braking system designed to prevent wheels from locking under heavy braking. By keeping the wheels turning, it helps a vehicle remain steerable during an emergency stop. The digitally controlled system, developed in collaboration with Mercedes-Benz, made its production debut in the Mercedes-Benz S-Class of the 116 series in 1978.

How it works

Wheel-speed sensors feed information to an electronic control unit. If a wheel is about to lock, the control unit signals a hydraulic modulator to reduce brake pressure. Pressure can then be increased again as the wheel recovers. This electronic adjustment of braking pressure is the central principle behind ABS.

Making the electronics durable enough for a car was an important development challenge. Earlier analogue designs had worked in testing but did not meet the reliability requirements of a braking system. Bosch contributed its experience in developing and manufacturing electronic components for vehicles.

Why it stands out

Bosch began its own preliminary ABS development in 1969. It acquired a stake in the Heidelberg specialist Teldix in 1973 and took responsibility for ABS development in 1975. The production-ready ABS 2 followed in 1978.

Its significance extends beyond preventing wheel lock. ABS provided the technical foundation for traction control and the electronic stability programme. Mercedes-Benz describes the 1978 ABS as the first digital assistance system in a car. By 1990, according to Bosch, around six million vehicles worldwide had been fitted with its ABS.

Where you meet it

ABS spread from luxury cars into other vehicle classes and became standard equipment across passenger-car segments. Bosch also developed anti-lock braking for motorcycles and launched its eBike ABS for electrically assisted bicycles in 2018. The same basic task links these applications: controlling brake pressure to prevent a wheel from locking.