Citroën technical note: arbitration on the DS hydraulic fluid (5 December 1955)

In this document

This "Technical Methods" sheet, addressed by Mr. Magès to Mr. Cadiou (copy to Mr. Pompon), deals with the choice of hydraulic fluid for the DS hydraulic control system, with the stated objective of a "Minimum cost price" p. 130.

The problem posed

Test note no. 222905 from the Central Lab indicates that a fluid other than VF 10 is being considered for the vehicle's hydraulic installation. Upon inquiry, the Central Lab actually recommends Antar F H 6 p. 130.

The financial arbitration

The sheet compares customer prices (1955 base) for 6 litres:

• VF 10: 1284 Fr (214 x 6), referenced "Pr A 669 of 1-12-55"
• Antar F H 6: 2610 Fr (435 x 6), referenced "appro note no. 79 of 17-11-55"

This represents an increase of + 1326 Fr per vehicle p. 130.

Magès concludes: "We request to keep the VF 10 for the DS as the price of the FH 6 is much too high", specifying that the price of the DS had already been established with the VF 10 p. 130.

A printed table "LOSS GAINS EXPECTED PER CAR" contains only one filled-in data point, in the column "CUSTOMER PRICE EXT. SUPPLY":

The document is dated "-5 DEC 195[5]" in the QM field, and referenced "File No. 43-4 (18)", manager Daumain, with a "Pr. A No. 672 / D434 of 1-12-55" p. 130.

Context

The DS 19, presented at the Paris Motor Show in October 1955, inaugurates the hydropneumatic suspension designed by Paul Magès, as well as hydraulically assisted steering and brakes. The choice of fluid circulating in these circuits is a major technical issue: viscosity, durability, compatibility with seals, but also—as this sheet shows—large-scale manufacturing cost.

The acronym "Antar" refers to a French oil brand of the time, while "VF 10" refers to an internal Citroën hydraulic fluid designation.

Archivist's perspective

This document concretely illustrates Magès's role not only as an inventor, but also as a technico-economic arbiter within the design office: he decides here in favour of the least expensive solution rather than the one recommended by the Central Lab, even though the DS is in the industrial launch phase p. 130.

The directive tone of the note ("We request to keep the VF 10") suggests that the decision ultimately rested with Magès's office, despite the contrary opinion of an internal technical department.

This document seems to be part of a larger file on the industrial development of the DS; it could usefully be compared with the Summary of folder 41-59: hydropneumatic suspension, rubber and DS developments, which structures all the documents relating to this period.