Handwritten note from Paul Magès to Mr. Cadron on pneumatic suspension classes (1957)

In this document

This handwritten note is addressed by Paul Magès to a certain Mr. Cadron, who asked him to "take stock of the different classes of pneumatic suspension solutions" p. 2.

The two sources of work

Magès announces that he is relying on two documents for his reflection:

1. A study published in SAE No. 78 of March 1957, dealing with the Cadillac Eldorado air suspension p. 2 — specified in a footnote as "UTAC Translation No. 57-64, Clast BEA Pb1654".
2. A lecture by M.A. Julien, given at the SIA, on the "fundamental characteristics of compensated pneumatic suspensions" p. 2.

Critical assessment of the two sources

Magès delivers a contrasted and quite sharp judgment:

• the SAE study is judged to be "based on precise facts", showing "with clarity the goal that the engineers set for themselves" and, with equal sharpness, "the results they were forced to settle for" p. 2;
• the SIA lecture is described as a "purely theoretical presentation", of which entire passages (mentioning "exact mathematical formulas" and a "hypothesis that does not hold") are finally crossed out by Magès himself, who simply concludes that it is "good to discuss" this lecture p. 2.

Announced plan

Magès structures his upcoming reflection into three chapters:

• A — Reflection on the SAE 78 report (Cadillac);
• B — Sizing of a "Cadillac" air spring for the DS;
• C — Discussion of Julien's SIA lecture p. 2.

Context

At this date, Citroën is developing and has just launched the DS, equipped with the hydropneumatic suspension designed by Magès — a solution based on gas and liquid under pressure, distinct from the purely pneumatic (air) systems then studied elsewhere in the industry, notably at Cadillac in the United States. The SAE (Society of Automotive Engineers) and the SIA (Société des Ingénieurs de l'Automobile) are both reference learned societies in the world of automotive engineering, whose publications and conferences are the subject of attentive technical monitoring by manufacturers.

Archivist's perspective

This sheet has the value of an internal working document: it is less a finished report than a methodological note, where Magès marks out, at the request of a colleague or superior (Mr. Cadron), the framework for a future reflection on competing pneumatic suspensions.

The numerous erasures visible on the page show Magès refining his critical judgment in real time — in particular on Julien's lecture, from which he finally removes the sharpest formulations.

Point B of the announced plan, concerning the "sizing of a Cadillac air spring for the DS", suggests that this reflection is part of a broader comparative work carried out by Magès at the same period, which is probably evidenced by the neighboring archives devoted to the SAE 28/78 report on the Cadillac Eldorado and to the comparison between Citroën hydropneumatic and Cadillac pneumatic suspension.