Handwritten study sheet: curves and mass-spring suspension diagram

In this document

A graph of curves

The upper left part of the sheet bears a graph drawn in pencil, the vertical axis of which is marked "C" p. 5. Several curves — three or four lines — start from a common low point and diverge upwards, with an almost vertical rise on the right p. 5. A horizontal line represents an axis at the bottom, and an intermediate vertical line cuts across all the curves p. 5. Two numerical annotations, which are uncertain, could indicate "100" on either side of the graph, but their reading remains doubtful p. 5.

A vehicle sketch and a mass-spring diagram

Below the graph is a schematic sketch of a vehicle seen from the side: two circles representing the wheels, connected by a horizontal line, with a hatched rectangle in the centre that could correspond to a mechanical component or a chassis p. 5. Under each wheel, a barely legible numerical annotation again suggests "100" p. 5.

In the centre of the page, a letter "F" topped with a horizontal line is inscribed above a second diagram: a vertical rectangle (block) placed on a spring drawn in a zigzag, with a point marked in the centre of the rectangle p. 5.

Material elements

The sheet is ruled/graph paper, bearing a graduated scale on the edges p. 5. At the bottom of the page, a printed box — oriented upside down relative to the reading direction of the sketch — bears the mentions "Sté AME A. CITROËN", as well as "N°" and "PAGE N°" fields that remained empty p. 5. In the upper left corner, also upside down, one can read the inscription "1A5-23" p. 5.

No date appears on the page; the general legibility is described as difficult and several elements remain uncertain or illegible.

Context

This type of sheet, with a "Sté AME A. Citroën" box and graduated paper, corresponds to the standard material of Citroën design offices from the era of the hydropneumatic suspension, of which Paul Magès was the inventor.

A "mass on spring" diagram like the one at the bottom of the page evokes, in a general way, the classic representations used in mechanics to study the oscillations of a vehicle (behaviour of an axle, a wheel or a suspension component facing an excitation). This connection remains, however, knowledge external to the document: no legend explicitly confirms this interpretation.

Archivist's perspective

This sheet has the character of a preparatory study or a calculation draft: the vehicle sketch, the block-spring diagram marked "F" and the graph of divergent curves suggest that it could be a sketch related to the analysis of a dynamic suspension behaviour, probably within the framework of work on the hydropneumatic suspension p. 5.

The reference "1A5-23" and the empty box (with no number or page filled in) suggest that it is an internal working document, not finalised for filing.

For lack of a date and usable legends, its precise attachment to a study programme remains hypothetical. It could nevertheless be in the same vein as the Magès calculation note: P55 suspension, leaf spring and 6 hydropneumatic spheres, which follows a comparable calculation approach, or shed light on the tests mentioned in the Pressure reading of suspension pneumatic blocks.