Finally posting

[Agnem]

...The motor-shaft simply goes round and round, like any other motor; IT DOES NOT OSCILLATE BACK-AND-FRO.
...

Picture the side rods of a steam engine.



Sorry... saw a chance to make a locomotive reference and I went for it. ;p

 

[MIDNIGHT RIDER]

Picture the side rods of a steam engine.



Sorry... saw a chance to make a locomotive reference and I went for it. ;p

Actually, that is a pretty good comparison.

A "pitman arm" sickle-bar mowing-machine is another.