Graphic records of clutch time as a function of control speed (17 September 1933)

In this document

A page from a graph paper test notebook

This double page of grid paper bears pencil-drawn curves, recorded during a test dated "17-9-33" p. 22, i.e., 17 September 1933.

Left part: clutch time

The upper page presents three curves annotated "Ye 20", "Ye 40" and "Ye", rising rapidly then stabilising into a plateau. A vertical handwritten text, partially illegible, mentions a "Clutch time as a function [uncertain] of the value [uncertain] [illegible] pulled [uncertain] from the control" with the mention "9/9" p. 22. Two braces under the curves indicate durations of "1'" and "1'25" p. 22.

Right part: engine and clutch speeds

The lower page bears a vertical scale of values (from 600 to 2400, with a parallel scale ranging from 10 to 40) associated with several curves. Annotations indicate a "slope due to the slowing down of the wind during declutching" p. 22, as well as durations "1'66", "clutching in 2"5" and "clutching in 5"" p. 22.

Reference lines are captioned "Duque", "Engine", "accel", "Clutch disc" and "Contactor engine plate / Engine" p. 22. An arrow points to a "Triggering / Clutch" point p. 22. At the bottom of the page appears the mention "Reduction ratio 1/100" p. 22.

Context

In 1933, Paul Magès worked at Citroën at a time when the company was exploring numerous mechanical solutions for its vehicles, with automatic or semi-automatic clutching being part of the pre-war research conducted by several manufacturers. This type of graphic record, measuring a mechanical response time as a function of a control, corresponds to a classic workshop testing practice of that period, where instrumentation relied largely on manual pencil tracings on graph paper.

However, nothing in the document allows this test to be linked to a specific Citroën model or project: this perspective remains external to the archive itself.

Archivist's view

This document appears to be a sheet of raw measurements, probably from a test bench or an experimental setup intended to study the response of a clutch system to a given control. The precision of the noted durations ("clutching in 2"5", "clutching in 5"") suggests a concern for quantifying a fine mechanical phenomenon, in the spirit of an experimental engineer that would later characterise Magès' work on hydropneumatic suspension.

The date "17-9-33" places this record in the same period as the handwritten folder "1933" listing several technical studies, which notably mentions the "synchroniser" — a theme close to the clutch issue addressed here. It is probable that this page belongs to the same set of tests conducted by Magès that year, although this cannot be stated with certainty due to a lack of additional elements in the document.