Summary of folder 41-59: hydropneumatic suspension and DS developments (1943-1959)

In this document

This document is the summary of an archive folder (folder "41-59", Box No. 2), titled "Hydropneumatic suspension, rubber suspension, BEA sessions and DS developments". It lists, almost day by day, all the documents contained in this folder, from 1943/1944 to 1959.

The beginnings (1943-1946)

The summary first lists the founding documents of the invention: the "List of problems under study" (22-02-1944), the "Plan of the synchronism indicator" (1943-1944), Paul Magès' note to Mr. Cadiou requesting a draughtsman (10-12-1944, the cover and the original note bearing 10-12-1943), the plans for "hydropneumatic suspension with differential interaction and automatic levelling" and the "hydraulic block of the spheres" (17-02-1944), as well as the "Bimetallic relay" (24-02-1944). The schedule of BEA work for 1945 and the notebook of the "1st test of the 2 CV with hydropneumatic suspension" (05-1946) close this first period.

Rubber / hydraulic comparison (1946-1953)

The summary mentions a "Comparison of rubber and hydraulic suspensions (TPV - PV - PVL 6)" as well as correspondence with Michelin and Laboratory reports p. 2.

The DS: development and incidents (1954-1959)

A large section details the tests and incidents related to the DS: test of the "15 Six H" by Paul Magès (03-04-1954), Laboratory notes on cold, mountains, piping (Dec. 1955-Feb. 1956), the "Citroën/Simca affair" (23-02-1956), the Monte-Carlo Rally (15-02-1956), the Milan Triennale (09-1957), the "Dowty" seals (Delerive/Magès exchange, Feb.-Mar. 1957), the "Hydraulic incidents notebook" (1958), and the DS improvement programme (H.P. pump and pressure regulator, 10-12-1958) p. 2-3.

Page 3 adds work sessions named: with Messrs. Bercot and Brueder on "catastrophic incidents" (10-1950), several conferences or sessions in the offices of Messrs. Pompon and Cadiou on the H.P. pump and DS/ID quality (Nov.-Dec. 1958), and notes by Magès on DS 19 braking (02-04-1958), the height corrector sealing cup (28-01-1959), a conversation with Mr. Duclos (02-07-1959) and the "automatic clutch control" (24-12-1959).

Context

The DS, presented by Citroën in 1955, revealed to the general public the hydropneumatic suspension designed by Paul Magès. The years following its launch are, as this summary testifies, marked by intense development activity: incidents reported from the field, climatic tests, dialogue with suppliers (Michelin, Dowty) and quality monitoring in the factory. The "pressure regulator" and the "high-pressure pump" are key components of the DS hydraulic circuit, regularly cited in the technical history of this system.

Archivist's perspective

This summary is a precious piece: it functions as a handwritten table of contents allowing the reconstruction, almost day by day over sixteen years, of the thread of Paul Magès' work — from the initial invention of the hydropneumatic suspension to the industrial monitoring of the DS.

It also reveals Magès' central place in Citroën's technical decisions: he is almost systematically the author or recipient of the notes cited between 1954 and 1959 p. 2-3, which suggests that he personally managed the handling of incidents reported from the field.

This document probably serves as a reading guide for the Cover of archive folder "41.59" and for the documents it announces, such as the List of problems under study as of 22 February 1944 or the Notebook of the first tests of the 2 CV with hydropneumatic suspension, which detail its content.