Dimensioned sketch of the hydropneumatic oil reservoir (parts 2962.S and 1699.S)

In this document

The sketch, titled "Réservoir" p. 12, shows a cross-section of a hydropneumatic oil reservoir with its air and oil circuits.

The internal mechanism

The diagram shows a wing nut equipped with a C seal, a vertical rod passing through this nut, a B spring housed in an upper chamber acting as a needle valve, and an A spring surrounding a threaded rod in the lower part p. 12. The flows are indicated by the mentions "air" (top left and bottom) and "huile" (right side and bottom) p. 12.

Part references

The bent tube leads to a fitting annotated "Joint 2962.S" and "1699.S"; at the bottom are the references "1301.S" and "Bouchon 1561.S" p. 12.

Note on mounting

A handwritten text specifies that "the mounting can be provided on the column casing" or that it "can itself form a reservoir", and that "the reservoir can also be fixed to the shell" p. 12.

Safety note on filling

A handwritten "Nota" warns: "the A needle valve must rest on its seat before the B spring is completely released, when removing the C nut, so that the oil contained in the reservoir does not flow into the lower casing due to the entry of air through the upper opening during filling" p. 12.

Context

This type of air/oil reservoir is part of the hydropneumatic suspension work conducted by Paul Magès at the Citroën design office, whose oldest plans date from 17 February 1944 (Plans de suspension hydropneumatique à interaction différentielle) and which would lead to the 2 CV tests in 1946 (Cahier des premiers essais de la 2 CV) and then to the presentation of the DS in 1955: a gas/liquid mixture provides damping and level maintenance there.

The ".S" references (2962.S, 1699.S, 1301.S, 1561.S) suggest an internal nomenclature of standard parts, common in automotive design offices of the time, but this precise numbering is not explained in the document itself.

Archivist's perspective

This sketch appears to be a detailed technical study, focused on a specific point: avoiding accidental draining of the reservoir during filling p. 12. The presence of standardized part references probably indicates an already advanced design stage, close to industrial production.

It seems linked to other reservoir sketches kept in the same collection, notably the Croquis du réservoir d'huile : pointeau, joints et fixation, which deals with similar elements (needle valve, seals), as well as the Croquis manuscrit d'un tube air/huile remplaçant la jauge d'huile, which explores a similar function of oil level control by air/oil. These connections remain, however, classification hypotheses, as no date or cross-reference is present on page 12 itself.