Drawing of cylinder D334-25a — hydraulic control for fork shafts (1955)

In this document

This technical drawing concerns the cylinder D334-25a, designated as "CYLINDER for hydraulic control of fork shafts". The reference dimension is Ø1 = 24 (mm), from which form tolerances are defined: maximum run-out of 0.1 (mentioned twice) and maximum warping of 0.2% and 0.5% p. 21.

The document specifies that the part must "satisfy plans D 334-45a and D 334-49a", associated assembly plans p. 21.

Dimensions and diagrams

Three technical views appear on the plate:

• a "COUPE.A" at scale 2, showing the part in section with diameters (Ø1, Ø2, Ø5), angles (10° to 15°, 5° to 10°, 35°) and "sharp edges — burr-free" tolerances;
• a detail view of the threaded/splined end, with "Ch 1.5 max at 45°" chamfer and dimensions 24.15 -0.05 / 35 +0.2;
• a small diagram at the bottom right bearing the mention "Flat allowed Ø=3 max".

Variant table

A table groups the dimensions of two comparable references:

The administrative title block indicates a validation chain: drawing by KOU J on 30-3-55, verification by BASTIEN on 8-4-55, industrialisation GUYETANT, as well as signatures from the Lab (POMPON), M.T. (CANEAU) and B.E.A. (CADIOU) p. 21. The plan was "launched by note no. 25141" and attached to assemblies D334-45a and D334-49a p. 21. A red handwritten note "54 to 57" appears in the margin, affixed after the drawing p. 21. The "MODIF" line lists four numbered modifications (m1 to m4) with their note references (25289, 25872, 26624, 26675) p. 21.

Context

This type of part — hydraulic control cylinder for fork shafts — is part of the hydraulically controlled gearbox mechanisms developed at Citroën in the 1950s, a period when the company was experimenting extensively with hydraulics applied to transmission, in parallel with the hydropneumatic suspension developed by Paul Magès. The acronym "B.E.A." refers to Citroën's Automotive Design Office (Bureau d'Études Automobile). This information is general knowledge about the company and is not stated in the document itself.

Archivist's perspective

The date of 8 April 1955 corresponds precisely to the verification by BASTIEN recorded in the title block p. 21; the drawing itself is dated 30 March 1955. This plan documents a technical variant — "2nd, 3rd and 4th gear cylinder" — compared directly to that of the D334-46a ("1st and reverse gear") in the same table, which suggests a family of standardized parts for different gear combinations p. 21.

The mention "54 to 57" links this part to a broader documentary set on clutch/control cylinders of this period, as evidenced by the handwritten divider "54 to 57 — Piston, clutch cylinder". It could also be usefully compared with the drawing of body D314-11, a part from the same family of hydraulic control components, although not explicitly linked in the document itself.