For flows up to approximately 0,3 Qn, the upper bearing pin centres the impeller wheel without wear-off against the concave jewel.
Magnetic forces keep the impeller wheel in the upper position.
For flows ranging from approximately 0,3 Qn to Q max, the impeller wheel with his cover jewel is led onto the lower bearing pin. Increased hydraulic forces keep the impeller wheel in the lower position and are absorbed by the lower bearing pin.