[rotorwrench]

It does have a rubber donut type drive coupling on the one end with what appears to be some sort of clutch control on the other end. The large diameter disc in between has me baffled. It doesn't really look like a pulley due to its narrow width and may be more of a flywheel or part of the clutch design. A person can just barely see the narrow small diameter sprocket that is much like a bicycle chain sprocket. I can't really tell which end is the drive end and which end is the driven end and have no idea what it was designed to operate. It would certainly be interesting to know the story behind it.