Balls of Ruby

The gears in a modern automatic winding movement operate such that whichever direction the rotor is spinning in, the rotational effort will be translated into winding of the mainspring. While the arrangement of the gears is simple enough, the real problem is twofold, firstly to do so efficiently, so even small wrist movements will wind the watch, and secondly to do it in such a way that is long lasting. Many early full rotor designs were not the efficient winders we take for granted these days. Also, any time you look in an old watchmakers drawers – you’ll see countless older ETA, AS and even the occasional Eterna or similar design, movements, with their pawl wheels missing and their automatic train holes oval.

MST 471

The movement we’re looking at in this post is the MST 436/470 Roamer 44 jewel automatic from the early 1960s, in which Roamer, decided to do something much more interesting…
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44 Rubies

The MST 436/470 (437/471 with date) was a prestige movement family designed and produced by Roamer in from 1964 in a no expense spared effort to move the brand upmarket. It worked too, because the movement was innovative, robust and long lived. It featured in the top of the line Mustangs and Stingrays for almost a decade. With 44 jewels, the best versions of these movements have the most jewels (that I know of) that are really functional.

While not all 44 jewels are absolutely critical for good timekeeping, and some English old timers back in the 1800s would have argued that 7 jewels in a lever escapement are all that are needed, the added jewels do add to the longevity of the precision of a movement – that is, the length of time it will continue to work within design parameters. Lets look at where all these jewels live in the movement.

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