MT18 with three arms
Four arms on the unbalance wheel probably make little sense, because then two arms would always have to be lifted „stiffly”. But three arms could even be advantageous. For one thing, there is always a flying weight, that stays near to the rim (and drifts all the time) and then the so-called Motus now fits well for lifting the unbalance.
The Algodoo scene is available for download here, it contains only simple scripts (ratchet and springs).
You can see that a stamper is also active in the scene.
It gives the initial impulse to lift the unbalance.
If you leave it out or reduce its weight, the torque
in the simulation is no longer sufficient to lift the unbalance wheel.
Even when in Bessler wheels the mechanics from stampers
to unbalance lifting are differently solved,
you can see here what the stamper unit is for.