Bowden cable gearbox control sketches (19-20 August 1933)

In this document

Page 26 (19 August 1933)

This page gathers several study sketches around a gearbox control (annotated "BV"). It contains a series of mechanisms with articulated levers, springs and gears seen in profile, with a "return spring" housed in a "groove" provided for this purpose p. 26.

A set circled in pencil depicts a system of four articulated points connected by rods, evoking a deformable parallelogram, associated with a partial gear wheel p. 26. A cross-section of a splined cylindrical part is also sketched.

The term "Bowden" appears twice, accompanied by the mention "gam" and the indication "stronger", suggesting a reflection on the resistance or sizing of the cable p. 26. A large cross-sectional diagram annotated "BV" presents partial dimensions ("x 6", "x 4") associated with teeth and springs, as well as bent levers annotated "A", "V", "A F" p. 26. Two other annotations, barely legible, seem to refer to names or markers ("F." and a word close to "Ponoir") p. 26.

Page 27 (19-8-33, and possibly 20-8-33)

The date "19-8-33" is repeated, with a second uncertain mention "20-8-33" p. 27. The sketch, which is quite legible, shows two parallel vertical rods each bearing a series of small aligned circles (evoking perforations or notches), connected at the top by a transverse piece itself articulated to a wider arm equipped with two axes at its ends. Two small rectangles, halfway up the rods, could represent slides or fixing parts p. 27.

Page 28

The handwritten text on this page is illegible. The technical drawing shows a part in longitudinal section — a splined shaft or axle with several diameters, shoulders, threads at the ends and a small pinion p. 28.

Context

The Bowden cable is a classic mechanical device (sheath + sliding cable) used for a long time in the automotive and cycling industries to transmit movement at a distance — brakes, accelerator, or gearbox controls. Its use to actuate a gear change, rather than a rigid linkage, met the needs for flexibility of installation in the bodywork.

In August 1933, Paul Magès, who joined Citroën in August 1925 at 17 and a half, had been there for eight years; he would remain there for 49 years, first as an autodidact who moved from technical writing to the sub-Super-Control before entering the design office in the late 1930s (autobiographical notes). These 1933 sketches therefore belong to a period prior to his major subsequent achievements — the braking limiter for the TUB van (1939-1940), the first plans for hydropneumatic suspension as early as 1944 (plans of 17 February 1944) and the presentation of the DS in 1955 — but already testify to his taste for fine mechanical exploration.

Archivist's perspective

These three pages, compressed into two days (19 and 20 August 1933), reveal a moment of concentrated research: several variants of mechanisms with levers, springs and articulated parallelograms are explored side by side, probably to test different ways of transmitting the movement of the Bowden cable to the gearbox fork p. 26-27.

Page 27, which is neater, could represent a synthesis or a partial clean copy of the idea sketched on page 26, while page 28, which is very degraded, no longer allows its splined shaft diagram to be linked with certainty to the rest of the study.

This document is part of a set of works from the same year, as evidenced by the handwritten folder "1933" listing studies of gears, injection and synchronizer, which confirms Magès' interest in transmission mechanics during this period.