Paul Magès

Paul Magès (1908–1999) is known for his invention of the first self-leveling automobile suspension, known as hydro-pneumatic suspension. This system replaced conventional steel springs with an adaptive system of hydraulic struts, resulting in a motoring experience that felt like no other automobile of the era.

This suspension achieved its initial design brief, fast travel on poor road surfaces. This advantage is still noted today, especially in applications where ride quality is important, like ambulance design.

His formal schooling was modest – he earned his National diploma (Brevet d'Etudes du Premier Cycle), a preparatory course for the Académie des Arts et Métiers in Marseille. At age 17, he sent his résumé to Citroën, one of the major automobile manufacturers in France, where he was hired to maintain equipment. In 1936 he became a technical draftsman, and in January 1942, CEO Pierre-Jules Boulanger assigned him to the development department, to solve problems in the development of braking and suspension systems (including for the Citroën 2CV).

Magès studied published material on automobile suspension. He was puzzled by the conventional wisdom that a supple suspension system was incompatible with good handling. He had been assigned the task of producing a car with both qualities. He realized that the solution must be located in a variable suspension, one that is very flexible at low speed, and stiff at high speed and load.

This questioning led to experimentation and the eventual development of hydro-pneumatic suspension system, which combines easily compressible gas in an enclosed chamber, combined with the non-compressible, force multiplication properties of hydraulic machinery. The heavier the load, the higher the gas pressure, so the suspension becomes more rigid. Magès ultimately concluded that hydraulic fluid under pressure, delivered by an engine driven accessory –- a hydraulic pump – was the best way to achieve the desired result.

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