When I was about eight I saw a display unit for toy cars in a shop window. It was a wooden box with the cars following one another over an oval slot on the lid. Obviously there was some sort of belt arrangement inside. (I've since learned that these units were made by Meccano for Dinky Toy dealers, but I've never seen another one).
Such was its visual appeal I wanted to build my own in Meccano, but didn't have enough parts. Fifty-five years later, I'm more fortunate, although I still don't have any six-inch pulleys. This is only the mark 1.5; I still haven't achieved a belt arrangement that runs smoothly and doesn't slip.