Suspension cylinder project — technical sketch sheet (1944)

In this document

This unique sheet presents a set of technical sketches executed in violet ink on tracing or translucent paper, representing several cross-sectional views of a cylindrical mechanism.

The main views

In the centre of the sheet is a large vertical cross-section showing a piston connected to a connecting rod articulated on two circular bearings, one at the top, the other at the bottom, with hatching marking the solid parts. To the right, a second, shorter vertical cross-section appears to represent the same assembly from another angle or at a different scale.

The complementary views

On the left of the page are a narrow, elongated cross-sectional view of a tubular element, accompanied by a top view showing a hub or bearing with small radial elements suggesting balls or rollers. Other more modest sketches complete the sheet: a small circle with an internal rectangular shape (cross-section of an axle or roller), a series of eight small rectangles aligned in two rows drawn in a lighter line, a bottom view of a part with a circular hub, a small cross-section of a short tubular element, and a small rectangle with an inscribed circle isolated from the other drawings.

Annotation

A handwritten inscription appears at the top of the page, above the central right cross-section, accompanied by an arrow pointing towards the top of the mechanism. The text remains uncertain, but the word "Purge" is mentioned in the transcription, without certainty of reading — it cannot therefore be stated as clearly appearing on the document.

Context

The term "purge" evokes, in the vocabulary of the hydropneumatic suspensions subsequently developed at Citroën, the operation consisting of evacuating air from a circuit filled with liquid — a classic stage in the development of this type of system. This sheet dates from 1944, a period prior to the commercialisation of the DS (1955), at a time when Paul Magès was conducting preliminary research into fluid suspension principles: it was precisely on 17 February 1944 that he drew up his plans for hydropneumatic suspension with differential interaction, which is the same year as this sketch sheet, before the first tests on the 2 CV in May-July 1946 (Notebook of the first 2 CV hydropneumatic suspension tests (May-July 1946)).

It must, however, be emphasised that this connection with hydropneumatic suspension is based on general historical knowledge established elsewhere in the collection, and not on information provided by the document itself, which contains no explicit text allowing it to be identified with certainty.

Archivist's perspective

This document probably has the value of a working draft rather than a finished plan: the multiple juxtaposed views, at varied scales and angles, as well as the small annex sketches (balls, rollers, rectangular templates), suggest a phase of exploration or trial and error around the same piston-connecting rod type mechanism.

The uncertain mention "Purge" and the associated arrow reinforce the hypothesis of a device intended to contain a fluid, which would be consistent with the research that Magès was conducting at the same time on suspension cylinders, as attested by his plans dated 17 February 1944. It seems that this sheet is part of the beginnings of this work, without it being possible to state more for lack of more complete textual elements.

The difficulty of reading the medium (faded ink, rust stain) invites one to consider this analysis with caution, pending a possible comparison with other items from the same archive box.