Citroën Laboratory report on piping defects of a production DS (22 December 1955)

In this document

This report from the André Citroën Laboratory (53, rue Balard, Paris), dated 22 December 1955, records the examination of the hydraulic piping of a DS ELV. 964 taken directly from the production line, equipped with the "manual height adjustment" p. 133.

The document is addressed to several people in the Design Department, including Louis, Hartmann, Malleret and Magès p. 133.

Five anomalies noted

The report precisely lists five defects found on the vehicle:

1. Brakes: loose fittings on the supply tube to the front right brake and the bleed tube, causing a fluid leak p. 133.
2. Bundle of supply tubes to the gearbox: rubbing on the front deflector plate, with the beginning of wear on a tube; a minimum clearance of 10 mm is required p. 133.
3. Pressure regulator: insufficient clearance (5 mm instead of 10 mm) between the return tube and a fixed tube leading to the accumulators, and contact of the delivery tube ("hunting horn") with another fixed tube p. 133.
4. Suction tube between the gear selector and the HP pump: clearance of only 5 mm with the fuel suction tube, whereas 10 mm is necessary p. 133.
5. Clutch release cylinder: clearance poorly adjusted, corrected by 5 turns of the nut; the report notes that excessive clearance makes "the driving of the car very poor" p. 133.

In conclusion, the Laboratory requests, due to the difficulty in achieving the necessary clearances on the production line, to switch quickly to the new tube arrangements already produced and presented to the Design Department p. 133.

Context

The DS, presented by Citroën on 6 October 1955, is distinguished by its hydropneumatic suspension and its centralized hydraulic circuit (brakes, power steering, semi-automatic gearbox, clutch). This system, complex for the time, multiplied the pressurized piping in a restricted engine space.

The early production of the DS is known to have been marked by industrial difficulties linked to the technical sophistication of the vehicle, requiring successive adjustments between the design office and the assembly lines — which this type of laboratory report illustrates well, without these general elements appearing in the document itself.

Paul Magès, who joined Citroën in August 1925 and was a technical writer and then deputy head of the Super-Control before joining the design office, had already filed his plans for hydropneumatic suspension as early as 17 February 1944 (see Plans for hydropneumatic suspension with differential and central interaction) and led the first tests of the 2 CV in 1946: at the date of this report, he is therefore one of the reference designers of the system in question.

Archivist's perspective

This report testifies to the quality control work carried out downstream of the design, a few months after the launch of the DS. It seems to reflect the classic tensions between the precision requirements of the design office (the famous "clearances" between piping) and the constraints of mass production p. 133.

The presence of Paul Magès among the recipients is explained by his role as designer of the hydropneumatic system: he followed, or was directly concerned by, field feedback on his own hydraulic system, probably to arbitrate or validate the "new tube arrangements" mentioned in the conclusion p. 133.

This document could usefully be compared with the Summary of folder 41-59, which deals more broadly with the developments of the hydropneumatic suspension and the DS.