It is pretty clever.
A wheel with a rod offset on it, then through a fixed pivot point, then attached to the moving part would work as well. It has far more moving parts. The only real advantage it has over the simpler clever design is it is more easily adjustable.
An alternative might be to use an orbital sander and vibrate it.
I suspect it isn’t the brittleness as much as the stickyness. When rocks break they normally don’t adhere to anything or itself.
I realize this is an extreme example. This was wet char that was run through a meat grinder. It stuck together and formed balls/lumps all by itself. It stuck to the galvanized chute, and to the plastic bucket. It didn’t seem to stick to the cheap stainless steel the pan, Maybe SS Vs would work or a non-stick type of coating on mild steel.