So, if drum speed cuts fuel and ignition, how would drum speed ever exceed its programmed limit?
Even if the sprag is in a failed state, the drum would go 2.45 x engine rpm. But engine rpm is not the fuel/ignition cut determing switch, drum speed is.
Lets say I set max drum speed at 8000 rpm, if the sprag was in a failed state, engine rpm would only get to a little over 3,265 rpm before fuel/ ignition cut. A bit of inertia wouldn’t let it exceed the rpm limit, it would only prolong its deceleration.
That drum and everything that is spinning with it at 8000 rpm has more than a little bit of inertia. I don't know how far past 8000 it would accelerate but I think it's going to speed up before it slows down. If you're up on the converter at 5500 when the sprag fails the inertia from the rotating assembly alone will be enough to spin it up past 8000 and it all happens in the blink of an eye.
If you have a wheel come off a car at 60 mph, the first thing it does is pass the car because of the inertia.
Kevin
