Torsion tests of PVS and PVL rear axles (Citroën Laboratory, 14 March 1952)

In this document

This report originates from the André Citroën Laboratories (53, rue Balard, Paris) and concerns a specific test request, no. 42.401 of 5 March 1952 p. 102.

Purpose of the test

The laboratory announces that it has tested four rear axles on the torsion bench: a PVS series axle, a PVS special (no. 401.132.c), a PVL series axle, and a PVL special (no. 401.133.c) p. 102. The document specifies that "all the torsion curves of these different axles" are attached p. 102.

The page includes a handwritten date box indicating "14/3/52", a registration stamp "20 MARS 1952", the handwritten note "ETUDES - M. Magès", and a test number "220.678" p. 102.

Graphical results

Page 103 presents the graphical record of the rear axle torsion test, comparing PVS and PVL. A first pair of values is noted: θ = 0.207 radians and C = 62,000 mm.kg p. 103.

The graph, drawn by hand on graph paper, contrasts "Test" curves (PVS and PVL) with "Series" lines (PVS and PVL), with the axes "degrees" (1 mm for 1°) and "Torque" (2 mm for 1 M/Kg) p. 103.

Several numerical values punctuate the graph:

The graph sheet bears the handwritten date "12.3.52" p. 103, two days before the registration of the report p. 102.

Context

The acronym PVS likely refers, in the Citroën workshop vocabulary of the time, to internal designations of rear axle types studied for suspension projects. This type of torsion bench test was a common practice in automotive design offices to validate the mechanical resistance and flexibility of rear axles before they went into production — a crucial issue in 1952, as Paul Magès, who joined Citroën in August 1925 and became deputy head of the Super-Control (autobiographical notes), had been developing since his February 1944 plans (hydropneumatic suspension plans) the hydropneumatic suspension, tested on the 2 CV as early as 1946 (notebook of first tests) and which would equip the DS presented in October 1955.

Archivist's perspective

This document is a typical example of the technical validation work carried out in parallel with Magès' research on hydropneumatic suspension: it does not describe the invention itself, but one of the mechanical resistance tests necessary for its industrial development p. 102-103.

The systematic comparison between "series" and "special" axles suggests that it is likely a matter of comparing an existing part with a variant modified by the design office, in a logic of optimizing the axle's flexibility p. 103.

The handwritten note "ETUDES - M. Magès" p. 102 confirms that this laboratory report was intended for him or concerned him directly, which places it in the same work context as other items in the file, such as the Summary of folder 41-59 devoted to the hydropneumatic suspension and its developments towards the DS.