Summary of the folder "Hydrostatic Transmission (H.T.)" — Box No. 3 (1956-1974)

In this document

This document is the period summary of the folder dedicated to the "Hydrostatic Transmission (H.T.)" in Box No. 3 of the Paul Magès archives, covering the dates 1956 to 1974 pp. 164-165. It chronologically lists the notes, patents, tests, and plans gathered in this file.

Early notes and foundational patents (1956-1960)

The summary traces the origin of the project to a 1956 note by Paul Magès "concerning the necessity of transmitting movement by hydraulic means (Transmission, suspension, dynamo, ventilation, and starting) No. 570108", followed on 04-04-1956 by a note "on the reasoning applicable to a continuously variable transmission" p. 164. These two lines bear a handwritten annotation in the margin (circle with a cross), likely a sign of checking or verification p. 164.

The document also mentions, in 1959, two old patents by Louis Renault on hydraulic and liquid gear shifting (1908), cited as a reference in the folder p. 164. Several "adjourned" patents are listed in July 1960, concerning the drive of electric generators, regulation, and the control of hydraulic motors p. 164.

Tests and developments (1960-1968)

The summary lists concrete tests: on 29-06-1960, "test results of the efficiency of a 2 CV equipped with an H.T." with a "photo of the ascent of Mont Ventoux" (p. 164, associated handwritten annotation). Other entries mention the H.T. applied to the "DS fan motor" (1960), the "100 HP motor" (1962), as well as exchanges with Messrs. Fabien, Prestrelle, and Cadiou p. 164. An endurance test of the 2 CV A12 is mentioned for 1963-1966, and a list of 2 CV/3 CV tests for 26-11-1968 p. 164.

Final phase (1973-1974)

Page 165 gathers entries from 1973-1974: note on the "transmission problem of vehicle L" (25-11-1973), engine adaptation for an automatic variator (16-12-1973), a technical presentation on the H.T. (12-1973), the cumulative mileage of H.T.s (1973), the presentation of an H.T. for a 50 HP motor (1973), and finally the plans for the GS and vehicle L H.T. (1974) p. 165.

Context

As a general historical reference, the DS and the 2 CV are the Citroën models where hydraulics played a central role, the former through its hydropneumatic suspension, the latter through its mechanical simplicity — which makes an experiment with hydrostatic transmission on this economy vehicle all the more notable. The "vehicle L" mentioned corresponds, in the internal Citroën vocabulary of the time, to a project in development (nothing in the document allows for more detail).

Archivist's perspective

This summary is a precious piece for anyone wishing to reconstruct the chronology of a little-known project by Paul Magès: the hydrostatic transmission, conceived as early as 1956 as an extension of the hydraulic principle already at work in the suspension. It seems the idea matured for nearly twenty years, from the first theoretical notes to tests on 2 CV and 3 CV, up to the industrial plans of 1974 for the GS and vehicle L.

The handwritten annotations in the margin p. 164 suggest a later review or checking of this summary, probably during the filing of the archives.

This document serves as a gateway to the entire H.T. file: one may notably consult the handwritten note by P. Magès on the transmission problem of vehicle L or the record of mileages of H.T. test vehicles, both cited in this summary.