B.E.A. Note no. 859: Citroën's contribution to automotive safety (6 June 1970)

In this document

This typewritten note, referenced B.E.A. no. 859, is signed "P. MAGES 6/6/70" on the last page p. 6, which confirms the dating to the day.

A claimed "industrial courage"

The note opens with a profession of faith: Citroën is said to have "advanced automotive technology in the direction of safety and comfort" by refusing the commercial "path of least resistance" p. 1. Three milestones are cited: the front-wheel drive of 1934, the DS of 1955 "with hydraulic suspension and assistance", and for 1970 the SM as well as the announcement, "in September", of a "new 6 CV hydropneumatic" p. 1 — likely the GS.

The characteristics of the DS repeated on the SM

The text lists eleven technical points (p. 2 to p. 5):

1. front-wheel drive, considered "self-stabilising" because understeer increases with engine torque p. 2;
2. hydropneumatic suspension with high flexibility and automatic height correction p. 2-3;
3. "equal and parallel" levers limiting the variation of front wheel parallelism p. 3;
4. the pivot axis in the median plane of the wheel, presented as an exclusive feature: "to our knowledge, the only car that possesses this arrangement" p. 3;
5. tapered roller bearings on the rear arms p. 3;
6. front/rear anti-roll bars adjusted for an understeering tendency p. 3;
7. disc brakes at the front from 1955 — "first production car" — and at the rear on the SM p. 3;
8. a common high-pressure hydraulic unit for suspension, steering, gearbox and braking, with two independent braking circuits and automatic distribution according to load p. 4;
9. a "high pressure" supply reducing braking response time p. 4;
10. power steering, with a version of "absolutely new technology" on the SM, described as smooth, self-centring, and hardening with speed p. 4-5;
11. lighting with dynamic levelling correction introduced on the DS in 1965, supplemented by headlights steerable by the steering in 1967, then six headlights on the SM p. 5.

Conclusion

The note distinguishes the protection of occupants (passive safety standards) from the Citroën philosophy which aims rather to "minimise the possibilities of an accident" rather than "the consequences of accidents" p. 6, a formula underlined by hand in the document.

Context

This document is part of the well-known history of Citroën: the front-wheel drive of 1934 (Traction 7/11/15), the DS of 1955 and its million units mentioned on page 2, then the SM launched in 1970 and the GS announced for the autumn of the same year. Paul Magès, who joined Citroën in August 1925 and was then deputy head of Super-Control, had filed his first plans for hydropneumatic suspension as early as 17 February 1944 (hydropneumatic suspension plans); he is historically the inventor of this device equipping the DS and then the SM.

The acronym "B.E.A." probably refers to the Citroën Automotive Design Office (Bureau d'Études Automobiles), without the document itself making it explicit.

Archivist's view

This note seems to have an almost programmatic vocation: it is less a detailed technical report than a synthetic, almost promotional plea, where Magès defends in about ten points the unity of the Citroën doctrine regarding active safety, from the front-wheel drive of 1934 to the SM of 1970. It dates from 1970, four years before his retirement in September 1974 (photographs of retirement), after 49 years spent at Citroën.

The numerous handwritten underlinings (p. 2, p. 6) suggest an attentive re-reading, perhaps with a view to a communication or a publication — the final formula on "minimising the possibilities of an accident" rather than "the consequences" seems to have been particularly highlighted.

The document thus offers a rare summary, from the hand of the inventor himself, of the technical coherence between suspension, braking, steering and lighting. It usefully complements the more technical archives on hydropneumatic suspension and on the development of the SM, if any exist in the collection.