Nguyen Duc Thang is a mechanical engineer with doctorate located in Hue City, Vietnam.
He has used Autodesk Inventor 2008 to create all a YouTube channel FILLED with animated mechanisms. Shown above is his model for a barrel cam mechanism in which a rotational motion is converted into linear reciprocating one.
He has models for things I've never even glimpsed as a static image, much less a moving model. Check out this Archimedean spiral gear and pin gear (below). How on earth would you accomplish something like this another way? It not only reduces the speed of the rotating axle, but does so nearly in-line with the original input motion -- and all with just two interlocking parts!
He has modeled interesting cams, gears and linkages as well as, complete machines and machine tools. This is a treasure trove for the mechanically minded. Check out Nguyen Duc Thang's YouTube Channel.
[ Thanks Michael! ]