Handwritten note on the barrel-distributor contact and pressure reversal

In this document

The barrel-distributor contact

Magès notes that this contact "is ensured by... a spring and the reaction of the [uncertain term, perhaps 'frigmon'] helical [device]" p. 11.

He then explains that when the car drives the motor (i.e., in reverse operation), a pressure reversal occurs in the conduits, in the direction of the reaction of the helical device. This "retro pressure" acts on a piston so that "the thrust of the barrel on the distributor remains positive" p. 11.

Barrel drive and patents

The drive method chosen would have allowed for "reducing the crankshaft-to-output-shaft centre distance to a minimum" p. 11. Magès specifies that this solution "is only possible with a free distributor such as the one described in the patent" — the patent number is illegible p. 11.

Description of the radial hydraulic motor

The sheet then describes a radial-type motor, with a single stroke per revolution: the pistons, inclined alternately in one direction and then the other, have a spherical base that rolls on a rotating cylinder, eccentric around an axis. The position of this axis is chosen so that the variation in eccentricity leads to a "modification of the distribution timing" p. 11.

The cylinder blocks of the hydraulic motor rotate on the distribution axis; the transmission shaft plates are coupled to them, with complementary centering bearings p. 11.

The distributor is "floatingly mounted" and includes a timing reversal device, designated "(Winage - retro)", referring to an illegible patent number p. 11.

Powering the servos

Finally, the text indicates that the servo-controls of the "pressure generator" or hydraulic motors are supplied with high pressure, via a pressure regulator and an accumulator, the latter also serving "to supply the auxiliary servos and the car (suspension, brake, power steering, etc.)" p. 11.

Context

This sheet evokes principles found in research conducted at Citroën on hydraulic transmissions and generators, a field in which Paul Magès was a key engineer, notably via the hydropneumatics applied to the suspension, braking, and power steering of the DS and the ID.

Radial hydraulic motors with inclined pistons and a rotary distributor constitute a technical family known in industrial fluid mechanics, used in particular for hydrostatic powertrain units — although it cannot be stated that this sheet relates precisely to them beyond what is written.

Archivist's perspective

This sheet, difficult to decipher in places, seems to stem from design work or theoretical development rather than a test report: the tone is explanatory, almost didactic, with references to patents (numbers unfortunately illegible) which suggest that Magès was consolidating or justifying technical choices already protected.

The mention of a radial hydraulic motor and a timing reversal device suggests work ancillary to research on hydropneumatic suspension, perhaps linked to reflections on hydrostatic powertrain units found in a later handwritten note on the installation of a hydrostatic powertrain unit on the front axle.

The final mention of "auxiliary servos... suspension, brake, power steering" also recalls the general architecture of the DS/ID hydraulic system, without the document explicitly naming it.

The watermark visible on the reverse, with mentions of technical journals (Lancia, Mercedes, Renault, Berliet, oil viscosity), suggests that this sheet was written on the back of an existing page of documentation or technical press — a common practice of paper reuse in the engineer's working archives.