Plate No. 13 — Electric and automatic unlocking of the "rubber starter"

In this document

This technical plate, the thirteenth in a series, details two unlocking mechanisms for the "rubber starter", a device for starting an engine through the accumulation of elastic energy.

Electric unlocking

The upper part of the page presents a cross-sectional view of a horseshoe-shaped mechanism, with a central spiral spring, lateral toothed jaws or pawls, and attachment points. Two electric wires connect this mechanism to a "+" sign and a spring contact network, illustrating the principle of electric unlocking announced in the title p. 7.

Automatic unlocking based on temperature

A second diagram, in the lower part, represents a horizontal cylindrical device connected to a circular housing equipped with internal helical springs. This mechanism corresponds to the automatic unlocking based on engine temperature p. 7.

A final sketch shows an open rectangular housing containing a liquid (identified as the engine oil sump oil), traversed by a tube or rod — presumably the heat-sensitive probe that controls the automation p. 7.

The case of electric "rewinding"

The cylindrical device is also connected to a rectangular box equipped with a crank handle, associated with the label "CASE OF ELECTRIC "REWINDING"" — probably an electric motor intended to reset the mechanism p. 7.

The plate bears the handwritten signature "P. Magés" p. 7.

Context

The "rubber starter" is part of Paul Magès' research into engine starting systems as alternatives to the classic electric starter, at a time — 1945 — marked by severe material constraints (shortages, restrictions) that may have directed thinking towards energy-efficient solutions. Magès, who joined Citroën in August 1925 and was then a technical writer in the design office (Draft letter from Paul Magès to Mr. Sarre and interview plan of 11 May 1969), was working at that time on several technical avenues: it was in February 1944, a year earlier, that he had drawn up his first plans for hydropneumatic suspension (Hydropneumatic suspension plans with differential interaction (17 February 1944)).

This plate dates from the same period as these researches which led, later, to the iconic hydropneumatic systems of Citroën, although no direct link is established here between this device and the future suspension.

Archivist's perspective

This plate clearly completes the description of the rubber starter by detailing its unlocking modes, a key functional aspect for its practical use. The concern for safety and automation — via a temperature probe immersed in the engine oil — testifies to the care taken by Magès to design a reliable system in all conditions p. 7.

The "case of electric rewinding" suggests that he was considering several variants for resetting the mechanism, electric or manual, which suggests fairly advanced engineering work on this device.

This plate is best read in conjunction with Plate No. 12, which presents the general principle of the system, and with the associated patent project, dated the same day, which probably formalizes the whole.