Citroën Laboratory Report No. 220.629 on incidents with the ELV.238 prototype

In this document

This report originates from the André Citroën Laboratory (53, rue Balard, Paris), under test number 220.629, and concerns the hydraulic suspension fitted to the ELV.238 prototype p. 92. It consists of "endurance results" after 1,500 km of driving p. 92.

Observed incidents

The report lists three observations:

1. The ARMCO tube (4 x 6) from the front accumulator to the pump is "cracked at the fitting collar", causing a "significant leak" p. 92.

2. The accumulator fixed to the end of the pump causes, during engine movement, the "pump support to gape against the engine casing", resulting in an engine oil leak deemed "quite significant". The author indicates a preference for "the previous solution with the accumulator on the side member" p. 92.

3. The document recommends "taking care with the assembly of ARMCO fittings and tubes", noting that on the delivered cars, the bends are often made "over the knee" — a practice deemed "regrettable" because it prevents both judging the endurance of the tubes and measuring the consumption of LOCKHEED oil, described as "essential" p. 92.

The document bears a date stamp "15 FEV. 1952" and a handwritten date "14 | 2 | 52", as well as the handwritten notes "ETUDES" and "M. Magès" followed by another barely legible name p. 92. Two signatures appear at the bottom of the page, one of which bears the initial "A." p. 92.

Context

The acronym ELV refers, in Citroën test vocabulary, to a test vehicle/prototype; PVSC likely designates a Citroën suspension report (procès-verbal), but this goes beyond the document itself. These tests are part of the development period of the hydropneumatic suspension, for which Paul Magès had drawn the first plans as early as 17 February 1944 (Hydropneumatic suspension plans with differential interaction (17 February 1944)) and for which the first tests on the 2 CV took place in May-July 1946 (Notebook of the first 2 CV hydropneumatic suspension tests (May-July 1946)); this 1952 report is therefore situated in the middle of a long development process that would lead, after the test of the 15-Six H in April 1954 (Road test of the 15 Six H (ELV 412) by Paul Magès, 3-5 April 1954), to the presentation of the Citroën DS on 6 October 1955. The LOCKHEED brand, cited for the oil, was then a recognized supplier of hydraulic components in the automotive industry.

Archivist's perspective

This short laboratory report clearly illustrates the patient development work that preceded the culmination of the hydropneumatic suspension. It shows, at a still experimental stage, the very concrete defects — leaks, friction, artisanal assembly of tubes — that the team of Paul Magès, whose name appears in an annotation p. 92, had to resolve before industrialization. Having joined Citroën in August 1925 and become a technical writer then deputy head of the Super-Control (Draft letter from Paul Magès to Mr. Sarre and interview plan of 11 May 1969), Magès was then, in 1952, in the middle of the development phase of the suspension he had started designing eight years earlier.

The remark about the fittings "made over the knee" suggests that the chain from prototype to production was not yet stabilized in 1952, and that these manufacturing defects even disrupted the scientific evaluation of performance (oil consumption). This document could usefully be compared with other items in the same collection relating to plans for hydropneumatic suspension with differential interaction, which document earlier stages of this same research.