Summary of the Citroën hydraulic group for the meeting with FIAT (25 Nov. 1968)

In this document

Dated "25-11-68" p. 106, this summary classifies Citroën hydraulic equipment into three categories, with the handwritten red heading "(FIAT)" p. 106, confirming its destination for a working session with the Italian manufacturer.

Existing equipment (p. 106)

The list covers the hydraulic pump (7-piston for DS and trucks, or single-cylinder for the ID), the pressure regulator, the hydropneumatic accumulator (700 cm3 and 380 cm3 volumes), suspension cylinders and pistons, height correctors (DS, ID, G), brake valves (dual with automatic front/rear adjustment for DS and trucks; simple with constant ratio), power steering (DS, ID) and the semi-automatic gearbox with automatic clutch for the DS. Added "for the record" are the dynamic and directional headlight controls.

Equipment currently being scheduled (p. 107)

Included are the power-assisted steering, presented as "1st application", intended for "vehicle S", smooth when parking and hardening with speed; a simplified single-cylinder pump for vehicle G; an accumulator and a suspension sphere made of stamped sheet metal (motivated by "cost price") for DS, ID, truck and vehicle G; as well as a simplified suspension cylinder for G and DS.

Equipment under study (p. 108-109)

The list, which is more prospective, mentions: improvement of the DS power steering (quality, price), the study of replacement pumps with increased flow and reduced cost, including "a self-regulating version for elimination of the regulator"; improvement of brake valves; price reduction of height correction via electric control (uncertain annotation "(Hydr.)"); power-assisted steering for trucks; a "sensitive follower valve cylinder" for truck gear shifting; hydrostatic transmissions of 50 hp and 150 hp; a hydrostatic retarder for heavy goods vehicles; a hydraulic anti-roll system p. 108; an electronic control to automate the DS hydraulic gearbox; hydropneumatic suspension applied to Citroën heavy goods vehicles and buses; a hydraulic starter; and small hydraulic motors for fans, windshield wipers, and alternators p. 109.

Context

The 25th of November 1968 is two years before the industrial agreement between Citroën and Fiat (signed in 1968, with the creation of PARDEVI), a period of rapprochement between the two manufacturers which explains the preparation of such a technical summary document intended for an Italian delegation.

Citroën hydraulics, born with the DS in 1955 under the impetus of Paul Magès, had by then diversified well beyond just suspension: braking, steering, gearboxes, and projects for commercial vehicles and heavy goods vehicles, in continuity with the research conducted during the 1960s.

Archivist's perspective

This summary document offers a rare overview of the state of hydraulic research at Citroën at the end of 1968. It seems to have been designed as external presentation material, intended to demonstrate the extent of the company's know-how to an industrial partner — hence its pedagogical structure in three parts (acquired, ongoing, prospective).

Several items in the "under study" section — notably the hydraulic anti-roll (22°, p. 108) and hydrostatic transmissions — extend work already long-standing in the Magès file, as evidenced by the road test mentioning the hydraulic anti-roll and bottom-of-stroke damping as early as 1962.

Similarly, the path of an electronic control to automate the DS gearbox (23°, p. 109) probably echoes Magès' earlier reflections on the DS clutch and gear control. This summary thus appears as a valuable milestone for measuring, at a precise moment, the maturity and future directions of the Citroën hydraulic program.