Plan D 334-014 — Flow regulator: piston-body matching and test (10.2.1956)

Citroën technical plan D 334-014 dated 10 February 1956, prescribing the piston-body matching clearance (0.02 to 0.04) and a flow test of 420 cm³/min for a hydraulic regulator linked to systems developed by Paul Magès.

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Understanding this document

In this document

This technical plan from the Société Anonyme André Citroën, referenced D 334-014, designates a "FLOW REGULATOR" (lower title block). It is accompanied by a cross-sectional diagram of a symmetrical cylindrical part, with threads at both ends and an internal helical spring (visual elements).

Matching requirements

The upper frame contains precise handwritten instructions for assembly:

"Piston-body matching: the piston must slide in the body with a clearance of 0.02 to 0.04"

This mention is associated with the mark "Ⓜ1" (modification no. 1, also visible at the bottom of the title block: "MODIF Ⓜ1 2 25744").

Flow test

A functional check is also prescribed:

Parameter	Value	Page
Piston-body clearance	0.02 to 0.04	p. 3
Test flow rate	420 cm³ ± 20 cm³/min	p. 3
Test temperature	40 to 50 °C	p. 3

Title block and signatures

The plan is signed by Guyetant (Industrialisation), Meunier (Verification) and Bobelin (Drawing), the latter dated "10.2.56" p. 3. It was "RELEASED BY NOTE N° 25H84" and bears the mention "PLAN B.E.A", a single sheet. Several related references appear around the diagram: D 334-239, D 334-155, 4 929-S, D 334-240, D 334-241, D 334-242, D 334-015 p. 3.

Context

This type of flow regulator, associated with a very tight-clearance piston-body pair, evokes the precision hydraulic components developed for the hydropneumatic suspension and the hydraulic control systems of the Citroën DS, of which Paul Magès was the inventor: the first hydropneumatic suspension plans by his hand date from 17 February 1944 (Hydropneumatic suspension plans with differential interaction) and the DS was presented on 6 October 1955, a few months before this plan of February 1956. The reference "334" is found on several plans in the same technical file, suggesting a coherent hydraulic assembly linked to the controls or fluid supply of the DS. This information is part of general historical knowledge and is not stated in the document itself.

Archivist's view

This plan dated 10 February 1956 p. 3 illustrates the degree of dimensional requirement specific to the Citroën hydraulic mechanisms of the time: a clearance of a few hundredths of a millimeter between piston and body, controlled by a flow test at a regulated temperature.

It seems to belong to the same family of parts as Plan DS334-07a of 25 November 1955, relating to the assembly and matching of the piston-liner, the logic of tight matching and functional control being similar there. The proximity of numbering with the Specifications D 334-07 suggests that this regulator belongs to the same hydraulic assembly, although the document does not explicitly establish this link.

The presence of a "Ⓜ1" modification suggests that this part was subject to an adjustment after an initial definition, probably to refine the clearance tolerance or the target flow rate — but no date for this modification is specified in the document p. 3.