Magès' technical note on high-pressure hydraulic transmission (3 January 1948)

In this document

This technical note, dated 3 January 1948 ("3/I/48", p. 2), bears the title "Hydraulic transmission of high pressures under low strokes with very easy sealing gaskets" p. 2.

Proposed mechanical principle

Magès indicates that "one or more smooth pistons in a bore with G.6-H.7 fit is sufficient" and that "a precise screw in its nut as well" can "serve as a drive piston" with a thread "following OIN I3/I4" p. 2. The guiding idea is to obtain sealing without complex gaskets, thanks to the precision of the fits.

Sealing materials considered

The note mentions "good results with tallow as firm as possible or with paraffin (in the form used for candles)" p. 2.

It then mentions a product developed by I.G. Farbenindustrie A.G., presented with six precise qualities: almost incompressible, plastic ("tendency to follow the element during the return"), consistent, liquefiable by heating to 90° for introduction into piping, stable in storage, and not chemically aggressive towards steel and cast iron p. 2. This product is identified as the "Igelit" polyvinyl chloride from I.G. Farbenindustrie A.G., mixed with "85% Mesamoll I as a softener" p. 2.

Diagrams

Two sketches highlighted with red pencil accompany the text: the first shows a threaded screw mechanism passing through a bore with clamping lugs; the second, a ring in two articulated half-crowns, annotated by hand: "Used to create a clamping movement or to equalize pressures, the clamping movement coming from elsewhere" p. 2.

Context

I.G. Farbenindustrie was, in the 1930s-1940s, a very large German chemical conglomerate, responsible in particular for industrial plastics and polymers — this name is here only an external historical reference point to the document.

This note is situated in the period when Paul Magès, an engineer at Citroën, was exploring the fundamental principles of sealing and hydraulic transmission that would lead a few years later to the hydropneumatic suspension of the DS, presented in 1955. In 1948, this research remained at a stage of basic mechanical principles, still far from the complex system that would equip the DS.

Archivist's perspective

This document likely has the value of an early milestone in Magès' reflection on hydraulic sealing without special gaskets — a central issue for any reliable and compact pressure transmission p. 2.

It is interesting to note the empirical approach: testing simple materials (tallow, paraffin) then monitoring a plastic and hot-melt German industrial product, which suggests an active search for alternative solutions to classic gaskets from this period.

This document seems to be part of a continuity with the Handwritten notes on attitude correction and front/rear flexibilities, which also touch on the technical foundations of the suspension studied by Magès at the same period. It can also be compared to later work on fluids for shock absorbers, such as Test no. 219.084 on Vacuum/VP 100 oils, which extends this quest for materials adapted to Citroën hydraulic systems.