Photographic report of the servo-controlled anti-roll assembly — ELV 569 test (1960-1961)

Eight prints documenting the experimental assembly of a servo-controlled anti-roll system on a Citroën test vehicle, with a stabilizer bar torsion cylinder and road tests on wet ground.

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Presentation and original captions

On 17 July 1961, Paul MAGES described in a 6-page handwritten document a servo-controlled anti-roll device for a motor vehicle. Following this document, we are publishing: -Photos of two DS in a high-speed turn, the first is a production DS, the second is equipped with the servo-controlled anti-roll system, the photos are "telling" -Photos of the front left tire of the production DS, and of the front left tire of the DS equipped with the servo-controlled anti-roll system, on the same circuit, under the same driving conditions, notice the difference in tire wear -Photos of the installation of the servo-controlled anti-roll system for the front and rear suspensions, it is a test prototype, this is visible.

Understanding this document

In this document

The test vehicle

The eight prints document an experimental assembly identified by a handwritten inscription: "ELV 569 — 6/60 to 12/61 — 76,000 km" p. 9. This annotation places the test campaign between June 1960 and December 1961, for a cumulative mileage of 76,000 km.

The mechanical device

Several views show the assembly installed in the rear compartment: two transverse bars connected to levers and links, rigid and flexible hydraulic piping converging towards fittings, an elongated cylinder fixed by a flange and a coil spring p. 8. Another photograph shows a hydraulic distributor block, a cylinder held by a bolted bracket and a through-rod p. 9.

A close-up view, annotated "Front", "UP" and "DOWN", explicitly designates a "[Stabilizer] bar torsion cylinder" p. 10 — the central component of the anti-roll device. Another "UP/DOWN" view shows an assembly with a sphere (likely a hydropneumatic accumulator), a mechanical block with springs and links, and steering ball joints p. 11.

Road tests and details

Two photographs show a Citroën DS/ID type sedan in motion on wet or flooded ground, license plates "2013-W75" p. 12 and a partially legible inscription "[uncertain: 8175 W 78]" p. 13. Two final shots detail a tire and the running gear seen from below, without any legible inscription p. 14-15.

Context

The servo-controlled anti-roll device is part of the research conducted at Citroën on the hydropneumatic suspension, of which Paul Magès is the inventor. This type of servo-controlled stabilizer bar aimed to limit body roll in corners while maintaining the comfort specific to hydraulic suspension, a classic issue on DS/ID bodies of the time.

The tests on wet ground, visible here, correspond to the usual methods of dynamic validation of running gear on a test track — a common practice among manufacturers to observe vehicle behavior in degraded conditions.

Archivist's perspective

This photographic series concretely illustrates, through images, an assembly whose technical description is likely detailed in contemporary engineering notes, such as the Note "Servo-controlled anti-roll for motor vehicle" dated 17 July 1961 — a period that overlaps with the end of the "ELV 569" test campaign mentioned on page 9.

The mark "[Stabilizer] bar torsion cylinder" p. 10 constitutes the most precise clue in the document: it allows for the unambiguous identification of the function of the photographed sub-assembly, which is rare in this type of workshop report where components are not always labeled.

It seems that this report had the value of a test report — documenting the state of the assembly after prolonged use (76,000 km) — rather than a presentation or communication value. The views of tires and running gear p. 14-15, which are less specific, could relate to a wear check associated with the same campaign.