"Richard Casady" wrote in message
...
On Tue, 11 Dec 2007 20:13:03 -0800, "Calif Bill"
wrote:

Tension on the idler
pulley would sorta regulate the speed.

Only by allowing varying ammounts of belt slippage. You would get very
poor belt life. I have seen this kind of setup, My dad built a lawn
tractor with that kind of clutch. Had a transmission from the flap
mechanism on a B-17. It had only 3 horse or so.

Casady

Get your attributes correct. And there are variable transmissions for
belts. Some automatic according to speed. Variable width pullies. One
gets wider while the other gets narrower giving a bigger diameter.