Parts list 515 xxx and gearbox control sketch

In this document

Parts list (p. 51)

Page 51 presents a handwritten record of part references, all prefixed "515", likely related to the same mechanical sub-assembly:

The 515 471 tube is the subject of detailed machining sequences: drilling at 13.5 over a length of 165 (i.e., 2'75), then boring to 14 (+0.05/-0), for a final time noted as "2'65" then "2'" p. 51. Mentions of "gain" and "loss" accompany each time calculation (for example "+gain 1'30" for the 515 475 axle, or "-gain 1'15" for the 515 655 lever), which suggests a comparison with a previous reference time p. 51.

Gearbox control sketch (p. 51-52)

In the background of page 51 appears a dimensioned wireframe diagram (segments 60, 62, 200, 175, 195, 89, 178…) with the markers "PD", "MAR", "AR", "FD", "A", "B" — vocabulary typical of a gearbox control (Neutral/Direct, Reverse gear…). An oblique annotation mentions a "lever 60" to obtain a "horn 275" p. 51.

Page 52 continues this same sketch, with two symmetrical sets of levers, one marked "PD", the other "MAR"/"AR". Two handwritten notes calculate lever travels there:

"To have a travel at 65 one needs a lever at 885 in length, with a lever at 875 the travel is at 74" p. 52.

"To have a travel at 65 one needs a lever at 275 x long, with a lever 60 at 275 x long, with a lever 60 at 259" p. 52.

These calculations relate the length of a lever and the amplitude of travel obtained, in a logic of successive trials by trial and error.

Context

At Citroën, in the development workshop where Paul Magès worked, the parts lists and machining sequences were used to estimate the time and cost of manufacturing a part before its mass production — a common industrial practice, with no specific link attested here to a precise model.

The markers "PD" (neutral/direct), "MAR" (reverse gear) and "AR" (rear) correspond to the usual vocabulary of mechanical gearbox controls of the time, but nothing in the document allows for the identification of the vehicle concerned.

Archivist's perspective

This diptych of pages illustrates well the daily work of a mechanical design office: on one side the accounting rigour of machining times (seconds, gains, losses), on the other the empirical trial and error of calculating a lever's travel, two sides of the same optimisation approach.

The link between the "515 xxx" parts list and the gearbox control sketch is not made explicit in the text; it seems that the two documents were simply physically superimposed (the paperclip at the top left of page 51 attests to this), without their functional relationship being certain.

The logic of successive trials in the notes on page 52 — several lever lengths tested for the same targeted travel of 65 — is characteristic of Magès's working method, which can be found in other documents in the same file, notably the forms repurposed as sketch supports.