Yes that's right, this is how the rear part of the wheel works, I found it out recently and I'm already working in the graphics.
It is more or less like this:
1.- You detect the target, identify it, take bearing and range and make a guess of the AOB, then plug the values into the part of the wheel we have already. Now you have an idea of the course and can plot an intercept
2.- You make a second observation some time later (Note bearing, range and time between observations) and then turn around the wheel and use the rear part: You start by fiddling around with the medium wheel until the difference in bearing matches and find the AOB with that. You guess of the AOB in the first observation helps you start already with an aproximate solution. Now you read across the wheel and know also the distance travelled. It's time then to use the inner wheel and adjust the "time" between observations to that distance travelled -read in the outer wheel- and bingo! you can directly read target's speed at the outside ring
Wondeful tool, isn't it?
Stay tuned, I will post a downloadable template ASAP for the rear part of the wheel with a tutorial