Bernard's note to Jouny on Asnières hydraulic manufacturing (5 July 1973)

In this document

This internal note, addressed by Mr. Bernard to Mr. Jouny (with copies to Messrs. Ravenel and Fleury), provides an assessment of hydraulic manufacturing at the Asnières plant after 18 years of experience. The document is dated 5 July 1973 (entry stamp), but signed "The 2 July 1973" p. 178 — the note was therefore written on 2 July and registered on the 5th.

Results and figures

Bernard highlights that these results "astonish representatives of competing firms" who have visited the plant p. 176. He cites production and spare parts data:

Three factors explain these results: large-scale industrialisation at a micrometric level, the replacement of vegetable/synthetic oils with LHM mineral-based oil, and the improvements/simplifications by the B.E.A. p. 176.

Hydraulic components

Bernard reviews three key components p. 177:

• the 7-piston pump, efficient but complicated, with worn manufacturing equipment; he mentions a block pump that should "come out of the B.E.A." for a lower cost price;
• the pressure regulator, whose reliability is "remarkable" on all types of vehicles, but which would require a redesign for the G+L+B production rate increases;
• the suspension, for which he compares the cylinders of the D, G and L to highlight the progress in simplification, with modifications to the link rod and the double-radius-of-curvature grain improving reliability "without increasing the cost price".

Conclusion and screw-cutting

The conclusion p. 178 insists: simplification "must not take place at the expense of quality". Bernard mentions the Milly-la-Forêt seminars with network agents, and mentions competition from Borg Warner automatic transmissions. A second section deals with screw-cutting manufacturing, recalling investments in multi-spindle lathes between 1952 and 1956.

A handwritten annotation in red specifies: "Note before his retirement" p. 178.

Context

The LHM fluid, the hydropneumatic suspension and the pressure regulator are central components of the system developed by Paul Magès for the DS and then extended to the GS and CX models (here designated D, G, L, S, PL). The Asnières plant was historically the manufacturing site for Citroën hydraulic components. The Milly-la-Forêt seminars and the competition from Borg Warner (an American specialist in automatic transmissions) relate to the industrial context of the time, not detailed in the document itself.

Archivist's perspective

This document offers a rare overall assessment, seen from the production plant rather than the design office, on nearly two decades of hydraulic manufacturing. The handwritten annotation mentioning a retirement seems to concern Bernard himself, a manager or director at Asnières writing this note at the end of his career — and not Paul Magès, who would not leave Citroën, after 49 years of service, until September 1974 (see the photographs of his retirement). This tone of synthesis and transmission of experience is thus explained by the author's situation.

The insistence on the tension between simplification and maintaining quality echoes the concerns expressed elsewhere in the Magès collection, notably in BEA note 43.027 on the operational safety of hydraulics and in the note on the AP suspension, which document the technical developments mentioned here regarding the G and then L suspension.