DS mountain test report — André Citroën Laboratory, 5 December 1955

In this document

This document is a report from the André Citroën Laboratory (53, rue Balard, Paris), dated 5 December 1955, referenced "ESSAI N° 222 941" p. 132. It is addressed to a list of recipients including Ingueneau, Hartmann, Hermet, Magès, Louis, Malleret and Fleury p. 132, which confirms that Paul Magès was well informed of these tests.

The report follows tests of two DS vehicles in the mountains and highlights three technical points.

1. Manual height control

The text emphasizes that a manual height control is "essential for any car capable of driving in snowy countries": the automatic height correction can immobilize a DS on "20 to 25 cm of packed snow", which happened "unpredictably" to one of the two cars tested p. 132.

2. Hand-crank starting

Starting with the hand-crank is deemed "absolutely impossible, especially with a hot engine". The report notes that the crank is difficult to position and operate, that the "crank guide on the front of the car opened from the first turns", and that the lever arm is "too small". The authors deem it "urgent to review the problem", as a starter or battery failure would otherwise completely immobilize the vehicle p. 132.

3. Steering straight-line position cam

While driving, the cam bearing came out of its position, causing a return by the end of the spring and friction deemed "very detrimental": the steering, "very good", became "frankly bad". The report asks to review the spring attachment "quickly" p. 132.

Context

The DS, presented by Citroën in 1955, is famous for its hydropneumatic suspension with automatic leveling — the invention associated with the name of Paul Magès. The "mountain" tests mentioned here are part of the validation campaigns conducted before and after the model's commercial launch, intended to test the vehicle in extreme conditions (snow, altitude, engine speed).

Hand-crank starting, still mentioned in 1955, reminds us that at that time this emergency mode remained a safety standard in case of electrical failure, before its gradual disappearance from automobiles.

Archivist's perspective

This report concretely illustrates the tensions between innovation and reliability encountered during the development of the DS. The defect of immobilization in snow reveals an unexpected side effect of the automatic height correction, a system at the heart of Magès' work: the automation, designed for comfort and stability, turns against usage in winter conditions here.

The presence of Magès' name in the list of recipients confirms, without ambiguity, his direct involvement in monitoring the field tests of the suspension he designed.

The steering cam problem, although peripheral to the hydropneumatic system, shows that mountain tests also served to reveal classic mechanical weaknesses, to be corrected before large-scale industrialization.

This document is part of a larger file dedicated to the hydropneumatic suspension and its evolutions; it can be compared to the Summary of folder 41-59, which lists documents relating to the evolutions of the DS.