Technical drawing of cylinder DS 334-25 — Hydraulic control for fork shafts (1956)

In this document

A dimensioned drawing for two cylinders

The plan presents the technical drawing in half-section ("Section A") of a cylinder for hydraulic control of fork shafts, intended to satisfy the assembly drawings DS 334-45a and DS 334-49a p. 22.

A dimensions table distinguishes two cylinder references sharing the same drawing:

p. 22

Geometric tolerances

A second table, at the top of the drawing, associates each reference (Ø1, Ø2, Ø3, Ø7, F, F1) with a position and a tolerance: for example, a "max run-out = 0.06" on Ø2 relative to Ø1, a "max warping = 0.2%" on F, or a max run-out of 0.2 on Ø7 relative to Ø3 p. 22.

The drawing also details precise dimensions — "1 at 45°" chamfers, "r = 0.2 max" or "r = 0.5 max" radii, "75° ± 2°" angle — as well as a detail view (Section B, scale 5) of a groove profile p. 22.

Title block and quality tracking

The title block mentions the design office staff: Guyétant (Indus), Bastien (Vérif), Perrin (Dess), and the MT BEA laboratory team composed of Pompon, Caneau and Cadiou, with the handwritten date "6-10-56" p. 22. The material indicated is "Steel E.0", without treatment or coating p. 22. Three modifications are traced in the margin: (m3) "redone 27364", (m4) "10.21 27736", (m5) "21 29H01" p. 22.

Context

This type of dimensioned drawing comes from the Citroën design office (BEA), the department where Paul Magès developed most of his hydraulic inventions, including the famous hydropneumatic suspension of the DS. The "hydraulic control of fork shafts" suggests a gearbox or selection mechanism, a field where Citroën also experimented with semi-automatic controls at that time — but this link remains a contextual hypothesis, not attested by the document itself.

Archivist's perspective

This drawing illustrates the meticulousness of the dimensioning work at the Citroën BEA: every diameter, every chamfer is accompanied by a strict tolerance, a sign of demanding mass production. It seems that this part belongs to a family of precision hydraulic components similar to the clutch release cylinders documented elsewhere in the collection, such as the drawing of the clutch release cylinder D 314-02 or the BEA inspection of the clutch release cylinder D 314-02, dated barely three days before this one (3 October 1956).

The coexistence of two references (DS 334-25 and DS 334-46) on the same drawing suggests a logic of drawing economy, common in design offices of the time for parts that were geometrically similar but dedicated to different gear ratios.