Anti-lock braking system (ABS)

Mercedes-Benz and the invention of the anti-lock braking system: ABS, ready for production in 1978

ABS during final development tests in the W 116 series S-Class

ABS during final development tests in the W 116 series S-Class

In August 1978 Mercedes-Benz presented the second-generation anti-lock braking system (ABS), developed together with Bosch, to the press in Untertürkheim. The world-first enables a driver to retain steering control even during emergency braking. From December the innovation became available, initially in the S-Class sedans (116 series).

Mercedes-Benz TELDIX anti-lock braking system (ABS)

Mercedes-Benz TELDIX anti-lock braking system. When decelerated on a corner, the car with anti-lock braking system remains precisely on course. Without anti-lock braking system, the car skids off course when too much pressure is applied to the brake pedal.

Eight years before, in 1970, the first-generation anti-lock braking system for passenger cars, a system that had been developed together with TELDIX, had its world premiere. ABS is thus an example of the great staying power sometimes required to bring a product up to production standard – a responsibility which the Mercedes-Benz brand takes upon itself again and again with its numerous innovations.

Development over decades

Mercedes-Benz TELDIX anti-lock braking system

Mercedes-Benz TELDIX anti-lock braking system

An anti-lock braking system had been on the automotive engineers’ list of wishes for decades – it was, after all, expected to improve handling safety drastically by retaining steerability during braking. As early as 1928 the German Karl Wessel had been granted a patent on a braking force regulator for automobiles, but this design only existed on paper.

ABS during final development tests in the W 116 series S-Class

ABS during final development tests in the W 116 series S-Class

In 1941, an anti-lock regulator was tested with which, however, “only modest successes were achieved,” as the “Automobiltechnisches Handbuch” (Automotive Engineering Manual) reported.

Mercedes-Benz test car, model series W 114, used in development work on the anti-lock braking system (ABS) in the early 1970s. This vehicle is not equipped with ABS. The cage protects the front windscreen when the vehicle skids unguided into the barrier.

Mercedes-Benz test car, model series W 114, used in development work on the anti-lock braking system (ABS) in the early 1970s. This vehicle is not equipped with ABS. The cage protects the front windscreen when the vehicle skids unguided into the barrier.

Nevertheless, these first attempts set the course: an anti-lock braking system had to have sensors for measuring the speeds of each front wheel, as well as a control unit for recording and comparing the data measured by the sensors. This control unit was to correct excessive deviations by individually controlling the brake pressure at every wheel up to the point at which the wheel is about to lock.

The electronic control unit of the anti-lock braking system that was jointly developed by Daimler-Benz and Bosch.

The digital electronics control unit of the anti-lock braking system that was jointly developed by Daimler-Benz and Bosch.

However, the transfer of the idea into hardware for use on the road proved to be significantly more difficult than expected. The sensors did work satisfactorily as early as 1952, in an anti-skid system for aircraft, and in 1954 in a Knorr braking system for railways.

Better braking: Compact Mercedes-Benz sedans from the 201 series with and with-out anti-lock braking system (ABS) on the test track in Stuttgart-Untertürkheim, 1978.

Better braking: Compact Mercedes-Benz sedans from the 201 series with and with-out anti-lock braking system (ABS) on the test track in Stuttgart-Untertürkheim.

But in the car, the demands on the mechanical friction wheel sensors were much higher: they had to register decelerations and accelerations in wheel speeds, they had to react reliably in corners and on rough ground and work perfectly even when heavily soiled and at high temperatures.

Induction instead of mechanics

Mercedes-Benz TELDIX anti-lock braking system. In this test series, the car without anti-lock braking system crashes through the line marked by aerated-plastic cubes

Mercedes-Benz TELDIX anti-lock braking system. In this test series, the car without anti-lock braking system crashes through the line marked by aerated-plastic cubes

The problem was tackled not only by Daimler-Benz engineers but also at TELDIX GmbH in Heidelberg. The two companies did not make any headway with mechanical sensors, so they had to look for another, new solution.

Mercedes-Benz S-Class (W 116) with ABS, 1978

Mercedes-Benz S-Class sedan from the 116 series with anti-lock braking system (ABS) on the test track in Untertürkheim, 1978. When braking on corners, the anti-lock braking system retains the car’s directional stability and steerability provided the physically possible cornering speed is not exceeded.

In 1967, they came up with a solution to the problem in a joint effort – in the form of contactless speed pickups which operate on the principle of induction. Their signals were to be evaluated by an electronic unit which controlled brake pressure via solenoid valves.

Mercedes-Benz S-Class (W 116) with ABS, 1978

Mercedes-Benz anti-lock braking system: When braking on corners, the anti-lock braking system retains the car’s directional stability and steerability provided the physically possible cornering speed is not exceeded.

At the time, electronics still worked on the basis of analogue technology which was relatively susceptible to failure and consisted of complicated circuitry. Integrated modules did not yet exist. And yet, this proved to be a first, promising approach.

Mercedes-Benz TELDIX anti-lock braking system.

For this reason, Daimler-Benz introduced this first generation of an anti-lock braking system for cars, trucks and buses to the public on the test track in Untertürkheim on December 12, 1970 – with a resounding echo by an enthusiastic expert world and press. The principle had been found to be convincing.

Development of the production ABS

Mercedes-Benz S-Class W 116 model series (1972 to 1980)

S-Class 450 SEL 6.9. Vehicle without anti-lock braking system (ABS) on the slalom course. At the time, ABS was available at extra cost as optional equipment. Photo from March 2013 at the test track in Stuttgart-Untertürkheim.

Another eight years passed before Daimler-Benz was able to offer a reliably functioning anti-lock braking system for production cars; this time was required to give the prototype the degree of technical maturity and reliability that is indispensable for large-scale production. In development, the engineers benefited from the revolution in electronics. It was not until the invention of integrated circuits that small, robust computers could be built, capable of recording wheel sensor data in next to no time and reliably actuating the valves for adjusting brake pressure.

Digital electronics ABS system jointly developed by Daimler-Benz and Bosch

It took development partner Bosch five years to supply the first digital control unit to Untertürkheim for test purposes.  Digital instead of analogue: this meant fewer components with the advantage of the risk of malfunction being reduced down to virtually zero.

S-Class from the 116 model series (1972 to 1980). Vehicle without anti-lock braking system (ABS) on the slalom course. At the time, ABS was available at extra cost as optional equipment. Photo from March 2013 at the test track in Stuttgart-Untertürkheim.

S-Class from the 116 model series (1972 to 1980). Vehicle without anti-lock braking system (ABS) on the slalom course. At the time, ABS was available at extra cost as optional equipment. Photo from March 2013 at the test track in Stuttgart-Untertürkheim.

Thanks to digital technology, the electronic components were capable of recording, comparing, evaluating and transforming sensor data into governor pulses for the brakes’ solenoid valves within milliseconds. What’s more, not only the front wheels but also the rear wheels were included in the control operations.

1978:  The world’s first production ABS

Mercedes-Benz anti-lock braking system (ABS). Press conference, 1978.

Press conference to present the anti-lock braking system (ABS), 1978, in the Mercedes-Benz S-Class W 116 (1972 to 1980). It was in this vehicle that Mercedes-Benz introduced ABS in large-scale production, making it the first manufacturer in the world to do so.

Thus, it had taken a long, long time before Mercedes-Benz became the world’s first motor manufacturer in August 1978 to officially launch the second-generation anti-lock braking system and to offer it as an option from December 1978 – initially in the S-Class at a surcharge of DM 2,217.60. Since 1984, ABS has been standard equipment on Mercedes-Benz passenger cars. Ten years after the introduction, as many as one million Mercedes-Benz cars with ABS were being operated on the roads throughout the world.

Mercedes-Benz anti-lock braking system (ABS). Press conference, 1978.

Press conference announcing the series-production world premiere of the anti-lock braking system (ABS) in 1978. Key development engineers, all at one table: Dr Manfred Burckhardt (left, standing), Prof. Dr Werner Breitschwerdt (seated at the table), Joachim-Hubertus Sorsche (standing), Guido Moch (last on the right).

Mercedes-Benz also adopted a pioneering role where ABS for commercial vehicles was concerned. As early as 1981 ABS was offered for compressed-air brakes, a joint development with Wabco. ABS has been standard equipment on all touring coaches of the brand since 1987 and on all trucks of the brand since 1991. In late 1990, ABS also found its way into the Mercedes-Benz racing cars for the German Touring Car Championship.

Basis for innovations

Mercedes-Benz 280 SE (W 116), 1979

First Mercedes with ABS: S-Class (W 116), 1979

ABS development never stops. The complete control system is becoming ever smaller, ever more effective, ever more robust. The initial, typical pulsating of the brake pedal, indicating ABS activation, has largely been eliminated today.  However, the system not only optimally decelerates the car and retains its steerability, it also serves as the basis and pulse generator for the acceleration skid control (ASR) system, the Electronic Stability Program ESP®, the Brake Assist and of course also for the electro-hydraulic brake system, Sensotronic Brake Control (SBCTM).

Sensotronic Brake Control (SBC)

In Mercedes-Benz passenger cars, the wheel sensor data also serves less conspicuous functions in that it is, for instance, processed by the electronically controlled automatic transmission that adjusts to the driver’s wishes, the navigation computer, the DISTRONIC proximity control, the engine and windshield wiper control, the active suspension control (ABC), 4MATIC – in short, by everything in the car that is controlled on the basis of speed. The same naturally applies to trucks and buses.

Anti-lock braking system is a matter of course throughout the world today25 Years of ABS 1978-2003

If the anti-lock braking system is today taken for granted in virtually all cars of the majority of automotive brands throughout the world, we owe this to the commitment of the large number of engineers and technicians at Daimler-Benz and cooperation partners Bosch, TELDIX and Wabco, who searched for the best solution for this system which improves handling safety, avoids accidents and saves lives.

Mercedes-Benz presented the anti-lock braking system in a touring coach in 1979

This is what Heinz Leiber, the then head of ABS development at Daimler-Benz and also called the “Father of ABS,” has to say: “The anti-lock braking system – and with it Mercedes-Benz – was also a pioneer in automotive digital electronics.”

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