Magès' handwritten notes: "Presentation T.H. 50 CV" at the B.E.A. (15.9.64)

In this document

This handwritten sheet, dated 15.9.64, serves as a framework for a presentation of the hydrostatic transmission (T.H.) with a view to an application for a 50 hp engine, at the B.E.A. p. 5.

Milestones of the tests recalled

The author summarizes three key stages:

• "1st. TH Test — 4cm³ - 4cm³" on 22 December 1955, with an efficiency of 90% p. 5;
• "1st. 2 CV TH Test" on 29 June 1957 p. 5;
• "1st. long Mileage and Ventoux" on 29 June 1960 p. 5.

Relative efficiencies measured

An informal table compares the efficiencies according to the type of route, "at equal weight and same average speed":

The text specifies that "currently the relative efficiency is greater than 0.98 (without doing 'hard' mountain)" p. 5.

Endurance

The note mentions that the first 2 CV (A12) "is still running more than 200,000 km, of which the last 100,000 without dismantling for examination" p. 5. It also mentions "two generations" of systems "with constant power (2CV) at variable pressure and volume" (test range B1), as well as test durations: 900 hours in the laboratory and 1300 hours at the B.E.A. p. 5.

Context

The hydrostatic transmission is part of the research conducted by Paul Magès and the Automotive Design Office (B.E.A.) of Citroën, in line with his work on hydraulic systems (suspension, steering). The B.E.A. was then exploring continuous transmission solutions via hydraulic means, an alternative to classic mechanical gearboxes, particularly for popular vehicles like the 2 CV.

The Ventoux mountain, cited as a test ground, was a site renowned for testing the hill-climbing performance of Citroën vehicles and transmissions.

Archivist's perspective

This sheet has a summary value: it seems to constitute a crib sheet prepared by Magès or his team to retrace, in a few lines, almost ten years of T.H. development (1955-1964) before a strategic presentation at the B.E.A. regarding an application to a 50 hp engine p. 5.

The efficiency and endurance figures given here, in particular the progress measured between the first tests (90%) and the "current" situation (greater than 0.98), probably illustrate the argument intended to convince of the technical maturity of the system.

This document is part of a larger file on the T.H., the extensions of which can be found in the Record of mileages of test vehicles with Hydrostatic Transmission (1960-1973) and in the Presentation by P. Magès on hydrostatic transmission, written about ten years later.