Circular motion doesn’t seem as efficient as linear motion at first, until you consider that linear motion requires you to stop the shaft and reverse its motion repeatedly. That takes energy that could have been sent out as electricity. A spinning disk doesn’t have that downside, and has its own rotational inertia to help keep it going.
This design isn’t very efficient, and Tesla himself switched to rotary designs.
Source: https://hackaday.com/2019/12/03/building-a-mechanical-oscillator-tesla-style/
Circular motion doesn’t seem as efficient as linear motion at first, until you consider that linear motion requires you to stop the shaft and reverse its motion repeatedly. That takes energy that could have been sent out as electricity. A spinning disk doesn’t have that downside, and has its own rotational inertia to help keep it going.