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I don't understand the different specifications of the maximum force of a servo motor vs the torque of a rotary switch. In the following example, there is a servo spec'ed at "Maximum Torque at 6V: 18.3 kg-cm" and there is a rotary switch spec'ed at "Rotational torque (non-shorting variant): 70 (+- 30) mN·m". I guess both the dash and the middle dot indicate "times" (multiplication). How do I compare them? I would like to know if the servo is fit to rotate the switch without problems.

enter image description here

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  • \$\begingroup\$ The difference between kg and N is gravity. \$\endgroup\$
    – Solar Mike
    Commented Jul 31, 2023 at 10:37

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It's most convenient to convert both to the standard SI unit of torque, the Nm, the Newton metre.

To the accuracy that you need, 1 kg (more strictly 1 kgf) is 10 Newtons. The standard value is 1 kgf = 9.80665 N, though the weight of 1 kg will vary depending on where you are on the planet between 9.764 to 9.834 N).

So the servo can deliver 1.83 Nm.

The switch needs typically 0.07 Nm to turn, 0.1 Nm max.

Looks like the servo has plenty of torque available.

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    \$\begingroup\$ Imperial units. It may be lbf, but the metric version is the kilopond, abbreviated kp. But in metric countries, nobody would use it in torque specs these days over Nm and its variants. If you find a kp·cm spec (or even the abomination kg·cm) these days, more likely than not it is a clumsy attempt of metrifying an imperial spec. \$\endgroup\$
    – user107063
    Commented Jul 31, 2023 at 11:06

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