Plan DS 334-07a — Hydraulic gear/clutch control block type BB

In this document

The technical drawing (p. 4)

This drawing bears the reference DS 334-07a and concerns the "C.de HYDRAULIQUE de changement de vitesses ou d'embrayage type BB" (Hydraulic control for gear change or clutch type BB) p. 4. The official title block of the Société Anonyme André Citroën appears at the bottom right, with the mention "REPRODUCTION INTERDITE" p. 4.

The drawing presents several technical views: a detail view on the left showing an assembly with a threaded cylindrical axis, nuts and threaded tie rods; a central view composed of small isolated diagrams (hatched block, cylindrical part marked "A", oblong part referring to a mark "m1"); a "Section A" in cross-section of a cylindrical part; and a detail view on the right of a larger assembly, with a dimension "18 ± 2" p. 4.

Numerous part references appear, among which:

The title block also contains a series of fractions and numbers (⅔ 63, ⅚ 111, ⅚ 63, ⅘ 75, 28268, ⅙, 29972) whose precise function is not specified p. 4. Handwritten name inscriptions are mentioned as illegible or uncertain, so no usable content can be drawn from them.

Page 5

It bears a simple handwritten annotation in red ink: "Bloc Ch°.Vit. DS 55 56" p. 5, as well as rust traces likely left by a staple or paperclip, and an illegible impression from another page.

Context

This type of technical drawing is part of the design, at Citroën, of the hydraulic control system for the DS gearbox, for which the engineer Paul Magès is notably known for the invention of the hydropneumatic suspension. Having joined Citroën in August 1925 at 17 and a half years old, a self-taught man who became deputy head of the Super-Control, Magès designed the plans for the hydropneumatic suspension from February 1944 and followed the development of the DS, presented on 6 October 1955 (biography: [Draft letter from Paul Magès to Mr. Sarre and interview plan of 11 May 1969](/archives/brouillon-de-lettre-de-paul-mages-a-m-sarre-et-plan-d-entretien-du-11-)). The DS generalized the use of hydraulics to several vehicle components (brakes, suspension, steering, semi-automatic gearbox), which explains the presence of such a hydraulic control block dedicated to gear changing or the clutch. These contextual elements are based on general historical knowledge of the brand and other items in the collection, and are not all attested by the document itself.

Archivist's perspective

The handwritten annotation "Bloc Ch°.Vit. DS 55 56" p. 5 suggests, without certainty, a link with the years 1955-1956, the period of development and launch of the DS (presented on 6 October 1955) — which could shed light on the dating of this piece, currently unspecified.

The plan number DS 334-07a directly links this archive to the Plan DS334-07a of 25 November 1955 — Piston-liner assembly and matching, probably an earlier or complementary version of the same assembly. The Specifications D 334-07 bearing a similar reference (D 334-07) could also concern the sealing requirements of this same hydraulic block, although this link remains to be confirmed by a cross-examination of the two documents.

It seems that this plan illustrates the meticulous work of mechanical definition (dimensions, tightening torques, part matching) characteristic of the design office methods of Magès and his team around the DS hydraulic system.