I have to project a mechanism that transform a rotation of $30 \pi/\text s$ from a engine in a rotation of $(\pi/4)/\text s$.

One of the gears should be 120x bigger than the other, but this is too much.

The gears should have a ray $< 30\text{ cm}$.

How can I create this mechanism?

  • 1
    $\begingroup$ Two stage reduction, worm gears, harmonics gears. There are many options. $\endgroup$
    – Eric S
    Nov 16, 2017 at 2:29
  • $\begingroup$ An epicyclic reduction unit may work well... $\endgroup$
    – Solar Mike
    Nov 16, 2017 at 7:34
  • $\begingroup$ A harmonic drive could do this nicely in a small package and with near zero backlash and high torque. $\endgroup$
    – user6335
    Nov 16, 2017 at 9:18

1 Answer 1


In practice probably the best solution is to find an off the shelf gearbox with the reduction ratio that you require for example :

https://www.ondrivesus.com/gearboxes-speed-reducers (not a recommendation)

Unless you have specialist knowledge designing and manufacturing a high ratio gearbox from scratch is unlikely to be very cost effective.

That way you just need to find one which meets your requirements for reduction ration and torque capacity.


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