Technical plates of the hydraulic components of the Citroën 15 Six-H (1954)

Four cross-sectional diagrams detailing the pump, the suspension cylinder, the pressure regulator and a fitting of the hydropneumatic circuit of the 15 Six-H.

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Presentation and original captions

In 1954, Citroën presented the first car equipped with a hydropneumatic suspension on the rear axle, the 15 SIX H. In May 1954, the Repair Methods department released technical note no. 600 on this new vehicle, for the attention of the Dealers of the Citroën network. We are only publishing pages 1 and 2 as well as diagrams 2, 3, 4, 6 and 8 of this technical note. Note the simplicity of the diagrams of the hydraulic components, everything was still secret at the time. Particular attention to diagram no. 8, it represents the fitting that ensures the tightness of the hydraulic connections. It will remain for posterity "THE MAGÈS FITTING" at Citroën.

Understanding this document

In this document

This series of four technical plates details in cross-section the main components of the hydropneumatic circuit of the 15 Six-H.

Fig. 3 — The pump

The diagram represents a cross-section of the pump, with its two annotated flows: Suction and Delivery to the pressure regulator p. 4. The drawing shows helical springs associated with valves, as well as mobile pistons connected by a rod p. 4.

Fig. 7 — The cylinder and the pneumatic block

This plate details the suspension cylinder: a sliding piston connected by a rod to a clevis, a valve-based Shock absorber system, a line To corrector, and a Compressed gas sphere connected to the pneumatic block p. 5.

Fig. 4 — The pressure regulator

The diagram presents the pressure regulator, with its accumulator in the upper part, a mechanical block with balls and springs, and three annotated flows: Outlet to the corrector, Return to the reservoir and Inlet of pressurized fluid p. 6. A handwritten annotation added in purple/pink designates a Bleed screw A p. 6.

Fig. 8 — The fitting

The last plate shows in symmetrical cross-section a threaded fitting, with a gasket (seal) around a central tube and a dimension of "2 to 3 mm" indicated between two markers p. 7.

Context

These components belong to the hydropneumatic suspension system designed by Paul Magès and adopted in 1954 on the Citroën 15 Six-H, before equipping the famous DS in 1955.

The pressure regulator is a cornerstone of this system: it regulates the circuit pressure by isolating the accumulator from the network once the pressure is reached, a role described in these plates. The pump, the suspension cylinder with its compressed gas sphere (the "pneumatic shock absorber") and the fittings are the classic constituent elements of this high-pressure hydraulic circuit, supplied with LHM or vegetable oil depending on the generations.

Archivist's perspective

These four plates probably form the illustrative apparatus of a technical note intended for workshops or dealerships, as their style — annotated cross-sections, assembly dimensions — evokes practical use rather than a theoretical presentation.

The handwritten annotation "Bleed screw A" on fig. 4 p. 6 suggests a review or subsequent use of the document, perhaps in direct connection with repair instructions.

It is likely that these diagrams accompanied the Technical note to dealers no. 600, dedicated to repair methods for the 15 Six-H suspension, or complemented the Diagram of the hydraulic installation of the 6 H vehicle, of which these figures would detail the components seen as a whole.