Laboratory Report No. 220.620: incidents on the ELV.230 after 12,000 km

In this document

This report from the André Citroën Laboratory (53, rue Balard, Paris) records the incidents observed on the ELV.230 test car after approximately 12,000 km of driving. The document specifies that these defects "were seen on the car by Mr. MAGES" p. 93.

Shock absorber

A lack of damping at the rear, particularly noticeable on the rear-right wheel, led to the removal of the corresponding sphere: the shock absorber was found to be "unscrewed and fallen into the cylinder" p. 93. The shock absorbers themselves showed nothing abnormal, apart from a 1/10 shim slightly marked under the valve. The Laboratory took advantage of this disassembly to install shock absorbers compliant with the "latest drawings", with tightening increased to 1 and 3/4 turns p. 93.

Threaded tube between cylinder and sphere

Upon reassembly, the tube thread proved stiff in the cylinder, so much so that it was the sphere that screwed onto the tube p. 93.

Height corrector control

The fork had about 1 mm of play in the slide groove, leading to inaccuracy in the rear height correction p. 93.

Conclusions

The report makes three recommendations: firmly lock the shock absorber to the bottom of the threads; fix the threaded tube once screwed to the necessary dimension; reduce wear on the fork and the slide, in particular by avoiding significant sliding of the fork p. 93.

The document bears a stamp dated "8 2 52" and "15 FEV. 1952 - ETUDES", as well as a test number "220.620" (visual elements).

Context

The ELV.230 is a test vehicle used by Citroën to test the hydropneumatic suspension under development, a system that would later equip the famous DS presented on 6 October 1955. At the beginning of 1952, the endurance tests in progress were aimed precisely at tracking down mechanical weaknesses — shock absorbers, threaded connections, height correction mechanism — before industrialisation. This type of Laboratory report is part of the usual development process: driving, observing breakdowns, adjusting the drawings. At this date, Paul Magès already held the position of deputy head of Super-Control at the design office, a post he had held since joining Citroën in 1925 (autobiographical notes).

Archivist's perspective

This report concretely illustrates the field work of Paul Magès during this period: he did not just design, he inspected the car himself after the incident p. 93, which testifies to a direct involvement in monitoring endurance tests, consistent with his duties as deputy head of Super-Control (autobiographical notes).

The three defects noted — loosening of the shock absorber, stiff threading, fork play — affect sensitive points of the nascent hydropneumatic suspension, the theoretical genesis of which can be found as early as the years 1943-1944 in the theoretical study folder and in the differential interaction suspension drawings of 17 February 1944.

This document thus marks a late development stage, nearly eight years after the first drawings, as intensive road tests approached — including the 15-Six H test in 1954 — which would precede the launch of the DS in 1955.