I've been looking for the name of the wheel of which a few are visible on this picture (not the object itself, but the wheels that are used on it!):
I've been looking for terms like "counter wheel", "counter reel", and so on - but can't seem to find anything that names the actual wheels themselves.
I know that these wheels have a name as I've seen it before, but I can't recall what it was. If I had to describe it, "a numbered wheel that represents a counted digit, either stand-alone or as part of a larger number".