Since 1883, the railway has connected the old town of Königswinter in the Rhine Valley with the Siebengebirge and ends at the Drachenfels plateau.

Based on the experience gained from the projects with the Zugspitze and Wendelstein rack railways, we were commissioned by the "Bergbahnen im Siebengebirge GmbH" to determine the permissible wear dimension of the rack, "System Riggenbach".

In addition to the company's own regulation "BO-Drach 2011", the "Implementing provisions for the railway ordinance AB-EBV of the Federal Department of Transport, Bern" also had to be taken into account.

The aim is to ensure safe operation of the mountain railway and to find an economical solution for the teeth subject to wear.

The difficulty here was not so much the purely static aspect of the stress analyses, but rather the geometrically complicated meshing conditions of the cogwheel and rack in combination with the constant wear of the tooth. Our static calculation was approved by the inspection without any objections. This means that there is nothing to prevent another 140 years of operation of the Drachenfels railway.