Road test from 2 to 5 April 1962: hydraulic anti-roll and 100% power-assisted steering

In this document

This handwritten report, signed by Mr. Satin and dated 9 April 1962, recounts a road test conducted from 2 to 5 April 1962 over 2350 km, with three crossings of the Morvan, the crossing of the Luberon, the Maures and the Massif Central. Three experimental vehicles are involved: the ELV 621 (100% power-assisted steering and bottom-of-stroke damping), the ELV 607 (hydraulic anti-roll) and the ELV 858 (standard DS, serving as a reference) p. 18. Magès, Perrier, Thomas and de Failly are present p. 18.

Hydraulic anti-roll

The device reduces fatigue, improves precision in corners and eliminates the "leourrage" [uncertain] on the outer front wheel. The centering approaches a classic configuration while recalling that of the Flavia p. 18. The authors note more regular front tyre wear p. 19, but also "sharp clanking" in the front axle and a breakage of the auxiliary bar of the front height corrector, repaired on site p. 19. Points remain to be corrected: maximum heel of 4° not always reached, disordered transverse movements when exiting corners p. 19-20, and two surprising stalls at 50 km/h on wet ground p. 20.

100% power-assisted steering

The drive for the centrifugal governor broke twice (after 100 km then 50 km), forcing the test to be redone in the mountains p. 20. The return is judged "much too brutal" p. 20 and the locking in a straight line "less rigorous" than with the previous aerodynamic control p. 20. The precision is judged significantly superior to the standard model, particularly when entering corners and in crosswinds p. 21. A defect is noted in the power-assistance variations: the drop in hardening pressure during braking is judged too fast, with a risk in the event of a sharp turn after a long straight line p. 21. A previous test on ice had shown that the return helped to locate the centre point, unlike the standard model p. 22.

Bottom-of-stroke damping

Compared to the Paris-Bordeaux-Paris test of 19.9.61 on the "DS 622", we find transverse movements of fairly large amplitude, without wheel chatter observed — but the driving was only 350 km p. 22.

Conclusion

The bottom-of-stroke damping "works very well" subject to additional checks. The power-assisted steering and the hydraulic anti-roll "seem to be able to complement each other perfectly", and the authors advise against treating or industrialising them separately p. 23.

Context

These tests are part of the developments that will lead, within Citroën, to subsequent improvements to the DS — power-assisted and then power-steered (known as VariPower then DIRAVI) will effectively be marketed a few years later, as will developments in hydropneumatic suspension. This general context sheds light on the importance of these iterative road tests, but none of these elements is named as such in the document itself.

Archivist's perspective

This document clearly illustrates the Citroën method of comparative road tests, conducted in real and varied conditions (mountains, rain, city), with a constant concern for safety and driver fatigue. It seems to be an important milestone in the joint development of the 100% power-assisted steering and the hydraulic anti-roll, two devices that the test drivers judge to be complementary p. 23 — a recommendation that, probably, weighed in the subsequent industrial choices.

This report echoes the BBC meeting summary of 22 February 1962, which already addressed suspension and transmission shortly before this test, as well as the conference notes of 28 February 1963, which continue the reflection on suspension and steering the following year.