Handwritten calculation of the drive speed of a beater (52.4 beats/min)

A handwritten calculation note establishes, based on a motor speed of 4,000 rpm and a pulley train sketch, the drive speed of a "beater": 52.4 beats per minute.

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Understanding this document

In this document

This page is a handwritten calculation note aimed at determining the rotation speed of a "beater" based on the speed of a motor.

The calculation

The starting point is a motor speed of 4,000 rpm. The author applies a factor: "V Dyn = Vmot x 1.1", i.e., 4000 x 1.1 = 4,400 p. 16.

This value of 4400 is then linked by an arrow to a sketch of a pulley/gear train superimposed, bearing the numbers 1, 40, 20, 56, 20, 30 p. 16. These numbers are used to establish a reduction ratio, calculated as follows:

Calculation	Result	Page
(1 × 20 × 20) / (40 × 56 × 10)	400 / 670 ≈ 10/168	p. 16
4400 / 168	26.2	p. 16

The final result is doubled (the sketch suggests a two-stroke mechanism or two passes per revolution), giving:

"= 52.4 beats per minute" p. 16.

No indication of date, author's name, or part designation appears on this page.

Context

The term "beater" evokes, in the industrial vocabulary of the time, an organ animated by a rapid reciprocating movement — one thinks, for example, of a threshing, agitation, or pumping device in a machine.

Without other elements from the file, it is not possible to link this calculation to a specific system in the work of Paul Magès: the general context of his research (hydropneumatic suspension, oil regulation, injection) invites caution rather than hasty identification.

Archivist's perspective

This sheet probably belongs to a pre-project or dimensional verification phase: it is typically the kind of quick note that an engineer scribbles to validate a transmission ratio before transferring it to a final drawing.

The presence, in the same file, of a handwritten folder "1933" listing speed and synchronizer studies suggests that this type of speed ratio calculation is part of a series of similar works carried out during the same period, although this cannot be stated with certainty for this specific page.

The style — tight figures, summary dimensioned sketch, absence of fair copy — is consistent with the numerous informal work notes kept in this collection, intended more for the author himself than for transmission or an official archive.