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Mercedes-Benz SL, W 113 series – the first sports car with a safety body
- Targeted reduction of kinetic energy in impact area
- Safety concept included numerous measures in the vehicle interior too
- Every subsequent SL raised the standard of safety to a new level
Stuttgart – The Mercedes-Benz SL, W 113 series, launched in 1963, was the first sports car in the world with a safety body. It was designed so that the area impacted upon – both at the front and at the rear – would deform, thus reducing or completely dissipating the kinetic energy in the corresponding area. The vehicle interior, the actual passenger compartment, on the other hand, was designed to be rigid in order to act as a safety cell for the vehicle occupants. The safety body also contributed to the protection of other road users, which was an explicit development goal for Mercedes-Benz: it also absorbs a part of the kinetic energy for the other – insufficiently protected – road user involved in an accident.
The issue of the improvement of passive safety had been hanging in the air for quite some time. At Mercedes-Benz it was promoted by engineer Béla Barényi, considered the father of the vehicle safety body. In order to test how the safety body responded, the first simulated crash test was carried out in Sindelfingen with a test car of the W 110/4 series on 10 September 1959 as a crash against a stationary obstacle. At that time the first vehicle built according to the new bodywork concept was already on the market: the W 111 series, presented to the press on 1 August 1959 with its six-cylinder models 220, 220 S and 220 SE.
This had consequences for the W 113 series SL because its dimensional concept had already been laid down in October 1958. At the same time a decision was made in favour of Barényi’s safety body. The previous plan – to add a more powerful-engined and cultivated variant alongside the Mercedes-Benz 190 SL (W 121 I series) by equipping it with the six-cylinder engine from the 220 (W 111) saloon – was abandoned at this point.
As the floor assembly for the new mid and executive-class cars ranging from 190 D (W 110 series) to 300 SE (W 112/3 series) was already based on the principle of the safety body, the same floor assembly was used for the W 113 series of the SL, which was being developed at the same time. Although Barényi’s reflections were spelled out in a patent, they were not at the time as well-founded and confirmed as they were later to be by a series of crash tests. The accident test carried out with the W 110/4 mentioned above remained the only test in 1959. In 1960, the tests were expanded and also included roll-over tests. With them it was possible to demonstrate in practice the basic demands for the greatest possible rigidity of the passenger compartment against impact from any arbitrary direction, and the assigning of limited rigidity to the front and rear sections with the object of reducing the violence of the impact through their planned, energy-consuming deformation.
With the W 113 series of the SL, the concept was applied to a sports car for the first time; at the same time, the steering gear was moved back to the firewall, the steering column yielded to axial compression and additionally featured a joint to prevent the feared lance effect, there was an impact plate on the steering wheel, and later, in the 250 SL launched in 1966, an impact absorber was featured. These safety features were not offered by any other vehicle of this category anywhere in the world. The same is true for the elimination of hard corners and edges on control buttons and knobs on the dashboard, with its padded upper and lower edges, and the recessed door handles.
With each of the following SL generations, the issue of safety has been raised to new, exemplary levels. For example, series R 129 (1989 to 2001) set impressive standards with its sophisticated safety concept for an open-top sports car, including among other things a roll-over bar, which can be deployed to protect occupants within just 0.3 seconds in the event of the imminent danger of the vehicle overturning.