Conference with Mr. Cadiou (2 February 1960): hydraulic and suspension programme

In this document

A vast programme of hydraulic and electrical components (p. 128)

The first page lists a set of developments envisaged around hydraulic motors: electric generator (alternator, dynamo) with regulation, radiator and car ventilation grouped under an "AIR UNIT (centrifugal)", windscreen wipers, and a hydraulic starter powered by a "sealed accumulator" with single control p. 128.

Also noted are: a "100%" anti-roll device with roll bar correction, a project for anti-pitch linked to acceleration and braking, a two-stage reflection on power steering (specifications then implementation study) also adapted for heavy goods vehicles, and research on braking focusing on the sensitivity of the distributor and the pressure/effort relationship, with the boxed mention "INDISPENSABLE" to find a solution for brake shoes with a more constant effort/pressure ratio p. 128.

Hydrostatic transmission (p. 129)

Page 129 details a hydrostatic transmission architecture in several variants: double receiver with fixed displacement, generator (displacement not readable with certainty), then double receiver with variable displacement. The overall architecture provides for the generator/receiver grouping, reversing valves, check valves and a braking valve, as well as a regulation system (point 4°).

The text also mentions the use of the generator for engine starting and the supply of hydraulic motors for dynamo and ventilation p. 129.

At the bottom of the page, a note in red ink indicates that Mr. Cadiou was to ask Mr. Richard to define with the author the personnel necessary for the execution of the programme; a reinforcement of six draughtsmen, two technical agents and a "permanaire" (uncertain reading) is quantified, with a mention "Randle 24/7/60". A follow-up is noted: "Reviewed Mr. Cadiou on 2/3/60" p. 129.

Suspension and damping (p. 130)

The last page distinguishes two paths: hydropneumatic suspension (study of the piston seal — minimal friction, endurance) and classic air suspension, associated with the name "BOUGEARD", with a question regarding air damping p. 130.

For hydropneumatics, the programme provides for a study of damping laws with current shock absorbers and their combinations, the creation of a test bench, the recording of a car's "flow peaks", the analysis of damping "noise", as well as the verification of shock absorber laws at the end of travel, on the bench and in the car. A line also mentions suspension for heavy goods vehicles and for the 2 CV, as well as a "TRUCK BRAKING" point p. 130.

Context

Placed in its era, this document is situated at the turn of the 1960s, a period when Citroën was deploying the DS launched in 1955 and its hydropneumatic suspension, while exploring wider hydraulic applications (braking, power steering, transmissions). The 2 CV, then in full distribution, also benefited from constant technical developments.

These researches into "all-hydraulic" components (motors, starter, power steering) are part of a general trend in automotive engineering of the time to explore centralised hydraulic solutions, in competition with classic electrical solutions — without the document allowing us to know which ones were industrially adopted.

Archivist's perspective

This conference report with Mr. Cadiou appears as an exceptionally dense strategic planning document: it covers in three pages almost the entire spectrum of research conducted by Paul Magès and his team — auxiliary hydraulics, hydrostatic transmission, suspension and damping p. 128-130.

It seems to constitute an early milestone in the development of hydrostatic transmission, a theme that will be taken up and deepened in later documents such as the notes on the 50 HP H.T. presentation or the endurance monitoring of the 2 CV A12, and the mention of the human resources requested p. 129 probably testifies to the scale that this programme was intended to take.

The double blue and red ink, as well as the follow-up dated 2 March 1960, suggest a living document, annotated throughout the monitoring of the file rather than a simple static note.