Ringing out again after 18 months of silence: the bell "Petersglocke" of Cologne cathedral. Traditional bell technology meets state-of-the-art construction and coating techniques.
In the summer of 2016 an investigation by the European competence centre for bells ECC-ProBell revealed that uneven striking of the clapper – as a result of the offset hole in the bell cover – meant that the "Dicke Pitter" was no longer emitting its customary sound. It was subsequently discovered that a repositioning of the bell clapper could not only result in an improved sound, but also contribute to the long-lasting protection of the Petersglocke.
In collaboration with the Cologne University of Applied Sciences, the cathedral construction authority developed a new mount, to be realised by the company Dirostahl.
The special feature of this mount? It is milled from a single forged piece and can be moved horizontally to the millimetre via two double eccentric components. In addition, it is also equipped with a HEICO-TEC® clamping nut that guarantees a defined torque in the rod that carries the clapper and secures the bell. This mount is unique of its kind worldwide.
It is all the more important that this bearing element is protected against corrosion. This is where the corrosion experts from Dörken MKS came in. Working together with inhouse and contract coater Lisi Automotive BETEO Oberflächentechnik GmbH & Co. KG, the company applied the newly-developed product DELTA-PROTEKT® KL 170 RT to coat the mount. The sacrificial behaviour of the zinc flake coating delivers cathodic corrosion protection. A particular benefit of the new product: The protective coat has a thickness of just 4–20μm and dries at room temperature, eliminating the need for a curing oven. This meant that it could be applied to the 780 kg component on site, in the belfry of Cologne cathedral, via spray application. The clamping nut is also securely protected against corrosion.
After the mount and the approximately 600kg clapper were brought back into position, the nearly 100-year-old bell was able to ring out again to mark All Saints. Equipped with a highly-efficient corrosion protection solution from Dörken MKS.