Anti-roll control by a pendulum — technical diagrams (1946)

In this document

No text is transcribed on these two pages: only technical diagrams are described, with page 1 being largely illegible.

Page 1 — overview of the front chassis

The diagram shows a vehicle front chassis (axle, two wheels, steering system) seen in perspective. One can distinguish a fluid reservoir connected by piping to a pump or a circular distributor, itself connected to a splined transverse cylinder. From this cylinder, two Y-shaped pipes join a central cylindrical block placed between the front wheels, at the axle level. A pendulum — a circle suspended from a fixed point — appears to the right of the transverse cylinder, visually associated with this circuit p. 1.

Page 2 — complete hydraulic circuit

This page, clearly legible but without text, details a complete hydraulic suspension circuit with pendulum-operated anti-roll control. One can see:

• a fluid reservoir connected to a pump/valve;
• a first horizontal cylindrical block (distributor or actuator) controlled by a pendulum suspended from a fixed point;
• piping leading to a second cylindrical block, marked with a cross symbol;
• two vertical cylindrical elements, related to suspension spheres or accumulators, each connected to a wheel (tire/rim) via rods and an arm bearing a point marked with an "X" near the hub.

The diagram is symmetrical on both sides of the vehicle, suggesting a common control for both wheels p. 2.

Context

The principle of an anti-roll system controlled by a pendulum evokes, in the history of Citroën automotive engineering, the research conducted on hydropneumatic suspension, of which Paul Magès was the inventor. These 1946 diagrams are situated precisely in the period when Magès, having joined the design office after working from 1939-1940 on the braking limiter for the TUB van, had already established his first hydropneumatic suspension plans (17 February 1944, Plans for hydropneumatic suspension with differential interaction) and was conducting at that very date the first tests on the 2 CV (May-July 1946, Notebook of the first tests of the 2 CV with hydropneumatic suspension), before the culmination that the DS would represent in 1955. This general context is, however, not mentioned in the document itself: it contains no written date, no engineer's name, nor any reference to a specific model.

Archivist's perspective

This diptych of diagrams appears to document a stage of technical research on the regulation of roll by a hydraulic control system slaved to a pendulum, undoubtedly a preparatory or complementary variant to the hydropneumatic suspension devices developed by Magès p. 1-2.

The absence of text makes interpretation cautious: it is impossible to state whether it concerns only a front axle or a principle intended for all four wheels, nor to precisely locate this diagram in the chronology of the engineer's patents — the "1946" dating remains that of the initial segmentation, with no internal evidence to clarify it, but it coincides with the period of the first 2 CV tests, contemporary with the work on anti-roll.

It would be useful to compare this piece with other archives concerning hydraulic suspension circuits from the same period, notably the 1944 plans and the 1946 test notebook already identified in the collection, to better situate this pendulum control in the genesis of the Citroën anti-roll system.