The rotors are preloaded by springs pressing them against the stator ensuring stable contact between piezos and rotor. The spring force is set for optimum motor performance.
A load of 100-200 grams on the rotor or the axle will have little or no effect on performance. Heavier objects should be mounted directly onto the axle which needs to be supported by the customer’s mechanical design so that only rotational forces are applied to the rotors through the springs.