Hydropneumatic suspension cylinder drawing — stroke 100, S = 8 cm²

In this document

The title block at the bottom right indicates the title of the part: CYLINDRE de SUSPENSION (SUSPENSION CYLINDER), with the dimensions COURSE : 100 (STROKE: 100) and S : 8 cm² p. 14. A signature, the reading of which remains uncertain (possibly "Magès"), is accompanied by the date 5.1.44 p. 14.

Technical views

The page brings together several technical cross-sectional diagrams:

• a vertical cross-sectional view on the left showing a narrow cylinder with a thin internal part ending in a rounded cup, supplemented by a view from below of a circular four-branched splined part p. 14;
• a barrel-shaped or cylindrical sleeve diagram seen in profile p. 14;
• a circular cross-sectional view with two lateral notches, above a row of eight small hatched rectangular parts, evoking keys or shims p. 14;
• a large central diagram, the most detailed, representing the suspension cylinder itself: an upper head with a fixing pin, a double-walled cylindrical body, a central connecting rod or stem connected to two rounded ends, and an enlarged base equipped with a circular pin p. 14;
• a cross-sectional view on the right of a thick-walled cylindrical element presenting internal vertical ridges, surmounted by a wider hatched part p. 14;
• a small isolated diagram at the bottom right, a simple cylinder with a central circle p. 14.

A handwritten annotation connected by an arrow to the large central diagram bears a word of uncertain reading, possibly "Purga" p. 14 — no interpretation can be drawn from it with certainty.

Context

This type of drawing is part of the research work that Paul Magès was conducting at Citroën during the 1940s on the hydropneumatic suspension, a system that would later combine a compressed gas and a liquid to provide damping and self-levelling. This technology would be popularised on the DS, presented on 6 October 1955, but its technical foundations were developed from the beginning of the 1940s — the plans de suspension à interaction différentielle dated 17 February 1944 attest to this a few weeks after this document. The suspension cylinder is one of the central components of this system, responsible for transmitting forces between the wheel and the hydraulic circuit.

Archivist's perspective

Dated 5 January 1944, this drawing belongs to an early and intensive phase of the system's development, as evidenced by the precision of the multiple cross-sectional views p. 14; it precedes by a few weeks the plans de suspension à interaction différentielle of 17 February 1944, of which it could constitute a preparatory step on the dimensioning of the cylinder. It appears to be a working document intended for the drawing office, consistent with Magès' request to obtain a draughtsman formulated a few weeks earlier in his note à M. Cadiou.

The technical dimension "stroke 100, S = 8 cm²" suggests precise dimensioning work, to be compared with other drawings in the same file, including the drawings of 17 February 1944 cited above.