Barthélemy's note on the advantages of the frame for the "L vehicle" (8 November 1972)

In this document

This handwritten note, signed BARTHELEMY and dated 8 November 1972, lists five technical advantages of a "frame" applied to the "L vehicle" p. 174-175.

1. Engine vibration filtration

The frame would allow for "double-stage filtration of engine-related vibrations," which is all the more effective as the frequency increases p. 174. For an inline 4-cylinder engine, the author compares this solution to a conventional single-stage device and provides vibration reduction coefficients at frequency 2N:

p. 174

This result was reportedly "confirmed by recording on the vehicle, of the sound level" p. 174.

2. Road holding

The frame would ensure "good axle geometry during yaw movements while driving," a factor deemed necessary for good road holding, while filtering vibrations resulting from tire-road contact p. 174.

3. Wheel impacts

Horizontal impacts on each wheel would introduce "internal forces into the frame without stressing the body" — the rest of the sentence is crossed out and illegible p. 174.

4. Obstacle impact

The passage is partially cut off at the beginning of page 175; it concerns a movement (uncertain mention) "weaker of the frame at the level of the connections with the body," attributed to the higher mass of the frame + front axle + rear axle assembly, compared to a solution with separate front and rear frames p. 175.

5. Crash safety

Regarding safety, "in frontal impact, ⌐or rear impact¬" (mention added as a circled handwritten insertion), the rigidity of the central part of the frame would allow for "lesser deformations of the body and in particular of the floor" p. 175.

Context

The "L vehicle" is not identified in the document; it could be an internal Citroën project of the time, but no external information allows us to specify it with certainty here.

More broadly, in the early 1970s, Citroën continued the development of several projects using various body and chassis architectures, in a context where passive safety issues (frontal impacts, programmed deformation) were taking on increasing importance in the automotive industry, notably under the influence of emerging American regulations.

Archivist's perspective

This note is distinguished by its argumentative and technical form: it methodically lists five advantages of a "frame" solution, with numerical support that is quite rare in documents of this type p. 174.

It likely testifies to technical justification work, intended to convince a hierarchy or a project team of the interest of a frame architecture for the "L vehicle," in line with the concerns of Magès and his collaborators regarding vibration filtration and safety — themes already present in other notes in the collection, such as the one on hydraulic operational safety or the one on the AP suspension.

The author, Barthélemy, is not identified more precisely in the document; his exact role in the team remains, at this stage, unspecified.