Dimensioned sketches of general layout: wheels, dimensions and driving position

In this document

Page 13 — wheel/axle layout

The sketch represents two wheels (circles) connected by a horizontal line, with a series of dimensions in millimetres: 400, 900, 950, 83, 480, 900, 310, 1150 p. 13. A crescent shape is sketched between the two wheels, with a small central vertical line, which could correspond to a mechanical part or a support p. 13. Two small pointed circular symbols (⊙) mark reference points, one near the 400 dimension, the other near the 310 dimension p. 13.

Source: (p. 13)

Page 14 — driving position / seated occupant

A seated human silhouette, seen in profile (head, back, folded legs), is sketched on a schematic seat p. 14. Vertical dimensions mark the body: 340, 520, 730, 850, as well as a horizontal dimension "1050" at the level of the backrest/seat and a dimension "15" at the bottom of the sketch p. 14.

On the left, a vertical structure with two uprights bears a spacing dimension "32" p. 14. At the bottom of the sheet, two small complementary diagrams include the dimensions "300" and "900" (with semi-circular shapes evoking attachments or hinges), as well as "350" and "450" near a circle crossed by a vertical arrow p. 14. Two handwritten mentions are noted as uncertain and therefore provide no usable information here.

Context

This type of dimensioned sketch corresponds to a common practice in automotive design offices: defining, before any industrial drawing, the main overall dimensions of a vehicle — wheelbase, tracks, dimensions — and the position of a seated occupant, in order to verify the ergonomics of the driving position.

Paul Magès worked at Citroën from the end of the 1930s-1940s; he is particularly known for having developed, later on, the hydropneumatic suspension that would equip the DS. This archive dating from the 1940s is therefore situated upstream of this iconic invention, at a time when the engineer was exploring various technical paths, including more modest projects (pedal car in particular, documented in nearby documents in the same file).

Archivist's view

These two sheets seem to constitute a preliminary study of general layout: one for the chassis (wheels, tracks, wheelbase), the other for the driving position (seated position, backrest and seat heights). The numerous dimensions in millimetres suggest a fairly advanced dimensional development work, even if the absence of an explicit legend makes it impossible to identify with certainty the type of vehicle targeted p. 13-14.

The presence, in the same file, of complementary uncaptioned sketches on automotive silhouettes, as well as the series of sketches of a pedal propulsion mechanism, suggests that this sheet could be part of a set of research conducted in the same year 1940, probably around the same light vehicle project — without this being able to be affirmed with certainty from the sole content of this piece.