DS 314-02 clutch release cylinder plan and leak tester tightness test (1957)

In this document

This Citroën Design Office (BEA) plan bears the designation "CYLINDRE ET PISTON DE Cde DE DÉBRAYAGE (Assemblés)" (CLUTCH RELEASE CONTROL CYLINDER AND PISTON (Assembled)), referenced DS 314-02 p. 13-14.

The T-type detail

Page 13 presents a "Détail du type T" (T-type detail) at a 5:1 scale: a cam or lever-shaped part, with numerous dimensions (50, 27, r=5, r=10 "flat part minimum", 23, r=8, 16, 21) and toleranced diameters — Ø1 = 19 +0.021/0, Ø2 = 23.3, and 23.8 ± 0.05 p. 13. A "Coupe B" (Section B) is also shown, with a 60° angle p. 13.

The tightness test

The two pages bear the same handwritten requirement: the part "Devra satisfaire un essai d'étanchéité à l'air de 5 kg/cm² appliqué en P" (Must satisfy an air tightness test of 5 kg/cm² applied at P) p. 13-14.

Alongside this, the result of the test actually conducted is noted: "Essai d'étanchéité - Fuitomètre "Solex" 2,5 Kg appliqué en P, aucune fuite enregistrée" (Tightness test - "Solex" leak tester 2.5 kg applied at P, no leak recorded) p. 13-14. The Solex leak tester is therefore the device used to verify tightness, at a pressure of 2.5 kg, lower than the prescribed 5 kg/cm².

Associated part references are mentioned in the margin: 2423_S, DS 314-35, DS 314-12, DS 314-11, 4907_S p. 13-14.

The title block

The title block identifies the contributors: Guyétant (Indus), Belloncle (Vérif., visa dated 4.1.57), Bourget (Dess., visa dated 2.1.57), as well as Pompom, Caneau and Cadiou for the laboratory (Labo/M.T./BEA) p. 13-14. The mention "LANCE PAR NOTE N° 28311" (LAUNCHED BY NOTE NO. 28311) and "MODIF. (m1) 8 30451" also appear p. 13-14. The date 4.1.57, carried by the verification visa, corresponds to the established dating.

Context

In an automobile equipped with a hydraulic clutch — such as the Citroën DS with its semi-automatic transmission —, the clutch release cylinder ensures the transmission of the control from the pedal to the clutch release fork.

The air tightness requirement, common in Citroën hydraulic circuits of the time (LHS in particular), guaranteed the absence of oil leaks or pressure loss, which was essential for the proper functioning of the system.

The Solex leak tester, cited in the document, was an industrial control instrument used to detect micro-leaks on mechanical parts.

Archivist's perspective

This plan illustrates the rigorous quality control work carried out on parts designed under the responsibility of Paul Magès: the prescription of a theoretical test (5 kg/cm²) and its documented actual execution (2.5 kg, compliant result) show the design-validation loop specific to the Design Office p. 13-14.

It seems that this document belongs to a series of successive plans for the same DS 314-02 part, of which an earlier version dated 1954 can be found, the Plan D314-02 de 1954, as well as related parts such as the Plan du piston DS 314-12 (1957), dated the same day, 4 January 1957 — a sign of a batch of plans updated simultaneously.