Both metallic and various polymer plain bearings did not convince in tests of "Erwin Koppe - Keramische Heizgeräte GmbH". Metallic ball bearings not only seized too fast, but were too loud in operation. Alternative tests with polymer plain bearings led to excessive coefficients of friction, so that these were also discarded. The problem was to find a component that keeps the complete mechanism running despite very small installation space and is also durable, temperature-resistant and insensitive to dirt.
Two self-lubricating plastic ball bearings with the xirodur A500 material are used in the mechanical drive unit. They ensure that the wood pellets are fed to the combustion chamber via a roller. The biggest advantage lies in the high temperature resistance of the ball bearing material. Short-term temperatures of up to 150°C are easily possible and due to the absence of external lubricants nothing can get stuck inside the shaft. Thus, the plastic ball bearings always guarantee the required smooth running.