A small step motor and a cam is exactly what I had in mind. Will create a less noisy circuit.
For the main step motor I found earlier a 30Nm step motor for 200USD and its driver is about 100USD. I plan on watching the current and switching the thing off if the current is becoming bigger than a certain adjustable setting that I can tune with a potentiometer. That way I dont need a limiter switch to protect my master caster.
Actually the 14Nm were not calculated but measured with a counter-clockwise torque wrench.
So it looks I have answered my own question that I started this thread with.