[Rob Stehlik]

In answer to the first questions, this type of tensioner would probably be best suited to a drive system that is built with two side plates. A non cantilevered design. Then you could bolt this assembly on one of the plates under the chain run. Any extension spring should work, or you could even use surgical tubing.

I realize spring loaded tensioners don't work well on systems that drive in both directions. The purpose of this exercise was to come up with a mechanism to take up the slack in the chain as it stretches. I believe timing chain tensioners on motorcycles work the same way.

If you were to actually build one of these, calculating the optimal angle based on the coefficient of friction would be wise.

Using a one way roller bearing on a pivot arm is a neat idea! I was thinking of wrapping a torsion spring around a pivot to accomplish the same thing.