When I make a coveyor belt I like to use spaghetti hoops all linked together,with the tomato sauce licked off by cats of course,it would be silly to leave it on.And power it with ONE MILLION ants all chained together on a treadmill with a jam sandwich suspended above them.
To control the speed you just raise or lower the jam sandwich,it is an open loop control system but you cannot have everything now can you?