First pic is the disc which fits on the end of the crank and the second pic is the drive that the disc drives on in a similar manner to the Ariens self propelled mower. I can't see where any friction material was fitted and I haven't see any pics of the drive

Attachments
unnamed (16).jpg (618.13 KB, 114 downloads)
unnamed (41).jpg (356.63 KB, 113 downloads)