I think your right Dave. It will have a hole through the middle to make it like a seesaw. It will then be mounted on a small trolley so that it contacts the switch,another hole drilled through the end to attach a rod with a ring on the end.
The rod will then pass through a guide higher up the trolley.You can then turn it through it's speed range by just pushing down on the ring.
Saves all that bending over. what a brilliant idea, Dai