p86p11 | Linear to rotary motion converter @p86p11 | Uploaded 12 years ago | Updated 3 hours ago
Depending on the required length of the linear motion, converter may be bigger or smaller depending on the purpose.
youtube.com/watch?v=ERUhevHQnts

And this is a link to clip where the device is weighted with 18 kg of concrete bricks and powered with a 450W electric motor.