Oskar's Continuously Variable Transmission

This CAD model was designed by Oskar van Deventer, copyright (c), 1 January 2025.

Oskar's Continuously Variable Transmission (CVT) is based on one-way bearings. Many CVTs are based on friction. A well-know example is the DAF Variomatic (https://en.wikipedia.org/wiki/Variomatic), which uses a push belt between conical pulley plates. This is also used for bicycles by Peyman (https://www.peymancvt.co.uk/). Another friction-type of CVT is the Enciolo CVP (Continuously Variable Planetary, https://enviolo.com/technology/), which uses a planetary system of swivelling steel balls. Recently, Ratiorez announced their RatioZero CVT (https://www.ratiozero.com/, https://www.youtube.com/watch?v=mWJHI7UHuys) that uses one-way bearings (cf ratchets) instead of friction. The use of one-way bearings has the main benefit of being much less tolerances critical than friction-based CVTs. This brings the CVT concept into the realm of makers with 3D-printer.

My CVT uses a piston-like system. A ball chain is just to adjust stroke distance. There are three pistons, with relative phases of 0, 120 and 240 degrees, similar to three-phase electricity. Each piston drives two gears, connected with one-way bearings to the output shaft. One gear is for the forward motion of the piston, and one for the backward motion. So there is a total of six gears, and the system has six phases, one for each gear. The drive shaft is driven with a hexagonal gears. The purpose of the hexagonal gears is to even out the motion of the pistons. This assures that a piston is sliding at a constant speed when it is driving the output axles. This compensation system works exactly for any gearing ratio between the manually-driven input and the output shaft.

These are the additional (non-3D-printed) parts for this CVT.
-Six one-way bearings with an outer diameter of 22 millimeter, an inner diameter of 8 millimeter, and a thickness of 9 millimeter. It's product code is CSK8PP. I bought mine at https://aliexpress.com/item/33040222926.html
-A piece of commercial-of-the-shelf ball chain. I measured the balls to have a diameter of 2.2 millimeter, and a spacing of 3.08 millimeter.
-A whole bunch of M3x20 slotted cheese-head screws.

Here are some links about this design.
https://www.youtube.com/watch?v=E7QCl8vJGYk
https://i.materialise.com/en/shop/item/oskar-s-cvt
https://i.materialise.com/forum/t/oskars-continuous-vairiable-transmission-cvt-by-oskar/3832
https://twistypuzzles.com/forum/viewtopic.php?t=39966

Feel free to 3D-print an extra sample to give to a friend, as long as you mention the designer and don't charge money.

If you are planning to sell some samples, then please contact me for a license agreement. The royalty fee is 10% of your selling price.

Please do not upload the design to a commercial service, or redistribute the design in any way other than linking to the YouTube video: https://www.youtube.com/watch?v=E7QCl8vJGYk

Enjoy!

Oskar
1 February 2025

Contact: 
https://oskarvandeventer.nl/index_contact.php?subject=Print%20It%20Yourself


