Plan DS334-07a (25 November 1955) — Piston-liner assembly and matching

In this document

Assembly requirements

The plan specifies that parts must be "cleared of all abrasive particles" and that rubber components are "lubricated with VF10 B fluid" p. 6.

Piston-liner matching

A central technical instruction indicates that "pistons must slide smoothly in the liners" with a "maximum clearance" of 0.005 p. 6. The reference specification document is mentioned: "According to drawing No. 2 of D334-07" p. 6.

Dimensions and tightening torques

Several tightening torque values appear on the drawing: a torque of "0.5 mkg" for a part that cannot be identified with certainty, and two mentions of "Torque 2mkg-0.2" associated with references D334-152 and D334-190 p. 6. A dimension "—13—" also appears on SECTION A, associated with the reference "m2" p. 6.

Part references

The drawing lists numerous part references scattered across the cross-sectional views: D453-69, DS334-41, DS334-42, DS334-84, D334-30, D453-15, DS334-89, DS453-211 (with the instruction "orient the slot towards the return hole"), D453-26, D334-71, D334-74, D334-48, DS334-278, DS334-75, D334-83, D334-57, D334-151, D334-44, D334-31, D334-62, DS334-59, D334-33, D334-61, DS334-28a, D334-39, D334-96, D334-32, D334-92, DS334-63 p. 6.

Title block

The title block indicates the designation "Hydraulic gear shift and clutch control", the plan "BEA", machine no. 1, the reference "N DS334-07a" and the handwritten date "25-11-55" p. 6. The signatures mention Guyétant (Indus.), Meunier (Vérif.), Wampouck (Dess.), Pompon (Labo.), Caneau (M.T.) p. 6. The mention "Launched by note No. 14556" also appears, as well as a modification "(m) 38/427 and drawing 2" p. 6.

Context

This type of technical drawing is part of the industrial development of the DS Citroën, launched in 1955, whose hydropneumatic suspension and hydraulic gearbox control — designed under the direction of Paul Magès — constituted major innovations.

The acronym "SA André Citroën" and the mention "Reproduction prohibited" are typical of confidential engineering documents of the time, protected within the design office.

Archivist's perspective

This document illustrates the extreme level of detail required by Citroën in the manufacture of hydraulic components: a clearance of a few hundredths of a millimeter between piston and liner p. 6 testifies to the precision sought to ensure the system's sealing, probably linked to the requirements set out in specification D 334-07.

The explicit reference to "drawing No. 2 of D334-07" p. 6 suggests that this part is part of a coherent set of documents, to be compared with drawing D 334-014 on piston-body matching, dated a few months later — a sign of continuous work on refining manufacturing tolerances.

The handwritten date of 25 November 1955 p. 6 precisely places this drawing in the weeks following the commercial launch of the DS, a period when the design office still had to stabilize mass production processes.