Handwritten sketch of an air/oil tube to replace the oil dipstick

In this document

The sketch p. 9 represents, in cross-section, a long vertical dip tube, drawn in pencil.

At its top, two small thin conduits are annotated "Air" and "huile" (oil), each accompanied by an arrow; they meet in a nozzle-shaped piece fixed to the top of the tube p. 9.

The tube descends the entire height of the page; two zigzag lines indicate a break in the representation, a sign that only a portion of the tube is detailed in the drawing p. 9.

At the bottom, an internal piece is drawn with, again, two arrows annotated "Air" and "huile" (oil). A horizontal dotted line marks the "niveau d'huile" (oil level) p. 9.

A vertical dimension, drawn on the left along a large part of the tube, is accompanied by an inclined handwritten annotation whose reading remains uncertain ([uncertain]) — it seems to evoke a length "to be determined according to the level to be reached", but this text is not guaranteed.

Another annotation, also uncertain, suggests the intention to replace an existing element ([uncertain: "Je met a la place de la jauge d'huile" / "I put in place of the oil dipstick"]) — this point cannot be stated with certainty based on the provided transcription.

Context

Generally speaking, in automotive engines of the time, the oil level of the crankcase is traditionally checked by a mechanical oil dipstick (graduated rod that is removed to read the level).

The idea of a system combining air and oil in the same conduit evokes, by analogy, the principles of the hydropneumatic suspension developed by Paul Magès for Citroën, where air and oil cooperate in the same circuit to regulate a level or a pressure. This comparison, however, falls under general knowledge about Magès' work and is not stated in the document itself.

Archivist's perspective

This sketch seems to be a principle sketch rather than a definitive plan: the pencil stroke, the break in the representation of the tube, and the elliptical nature of the annotations suggest a preliminary stage of reflection.

It is likely that this drawing belongs to a broader reflection on oil level control, a theme found in other pieces of the same collection, notably the handwritten proposal for a constant oil level system for engine crankcase dated 3 December 1936, as well as another sketch of an air/oil device to replace the oil dipstick, very close in its subject.

Without an explicit date or signature on this page, the precise attachment to a phase of Magès' work remains hypothetical, but the thematic proximity to these neighboring documents invites us to see it as a stage in the same engineering journey around the control of fluid levels.