No, it cannot. As you can see in this video from the site where he explains the mechanism: https://www.youtube.com/embed/vbU1afvCRwc?version=3&rel=1&fs=1&shows

No, it cannot. As you can see in this video from the site where he explains the mechanism: https://www.youtube.com/embed/vbU1afvCRwc?version=3&rel=1&fs=1&showsearch=0&showinfo=1&iv_load_policy=1&wmode=transparent&enablejsapi=1 https://www.youtube.com/embed/vbU1afvCRwc?version=3&rel=1&fs... When he tries to move the red ring against the green ring (at 2:39), the thing doesn't budge. The gearbox concatenates two such transmissions, therefore, it cannot be operated backwards.