Do auto watches have a "too strong shake" safety system?
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Thread: Do auto watches have a "too strong shake" safety system?

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  1. #1
    Member Gabriel A. Zorrilla's Avatar
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    Do auto watches have a "too strong shake" safety system?

    Hi there. I notice when i swing too hard my Miyota movement the rotor moves fast but i do not hear the gears loading up, but when i move more gently i do and the rotor just moves a little, like 90º. Do autos or particularly Miyota movnt's have some kind of safety mechanism to avoid damage due too strong movement/g force?

  2. #2
    Member hans caravan's Avatar
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    Re: Do auto watches have a "too strong shake" safety system?

    Miyota movements wind unidirectionally. It's possible the sound you hear is the rotor spinning freely in the non-winding direction.
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  3. #3
    Member CitizenM's Avatar
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    Re: Do auto watches have a "too strong shake" safety system?

    Quote Originally Posted by Gabriel A. Zorrilla View Post
    Hi there. I notice when i swing too hard my Miyota movement the rotor moves fast but i do not hear the gears loading up, but when i move more gently i do and the rotor just moves a little, like 90º. Do autos or particularly Miyota movnt's have some kind of safety mechanism to avoid damage due too strong movement/g force?
    There isn't any safety against high RPMs on an automatic rotor, at least not on any conventional movement. All Miyota automatics, as it's been pointed out, are unidirectional winding and therefore the only resistance the rotor receives in the non winding direction is the friction between the parts (quite little, comparatively) and thus it spins at high speeds and create rotor wobble (the feeling of the rotor spinning) and noise. In the other direction, it's actually winding the watch and encounters a lot more resistance. I believe all Miyotas only wind counter-clockwise. So you will actually see the rotor meet some sort of "invisible" force in the winding direction that stops the rotor from spinning. If you will look at your rotor spin in the counterclockwise position when the watch has totally stopped, you'll see there's basically no resistance in either direction, but at full wind, when the mainspring is resisting, it won't go nearly as fast counterclockwise). Anyway, long story short, there isn't a protective mechanism to prevent high PRMs, and apparently, none is needed.

    There are some movements that have specialized shock protection for the rotor though, like the IWC 80111:



    See that weird "swan neck" shape that looks like its connected to the rotor? That's actually a spring that allows the rotor to move just a little vertically and horizontally and, in theory, safely dissipate some unwanted energy.
    KindaDevil likes this.

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