The Transrapid magnetic levitation system is propelled contactlessly over its guideway by a traveling electromagnetic field. To allow for touchdown in the event of a failure, the Transrapid is equipped with support skids that are lowered onto the concrete strips of the guideway. The newly developed support skids, with which the Transrapid 08 has been equipped at the Emsland test facility, called for a special four-layer coating on each of the two 15 cm wide strips. The dry films each have to be precisely 100 to 150 µm thick on the two 17 km strips - and the coating quality has to be immaculate.

Another requirement of the guideway, which also has to be fulfilled by the coating, is that it has to compensate for temporary heat-induced expansion of the main strength elements of the girders in sunshine. A heat-absorbent coating between the two strips has the purpose of remedying this.

The coating of the functional surfaces of the guideway and guideway table was a technically extremely demanding challenge - which the experts of multi-trade service provider PeinigerRöRo were happy to accept. Dipl.-Ing. Michael Rummel, responsible for Building Conservation: "Because we work in many fields, our company has acquired a huge reservoir of knowledge and experience. Adopting an interdisciplinary approach, we exploit these resources creatively and come up with innovative solutions. And this is undoubtedly one of our strengths." It is important, Rummel continues, to approach the in this case novel challenge systematically and apply existing knowledge imaginatively to the task. In joint development work, specialists from the fields of Building Conservation and Special Scaffold Erection quickly produced a technically watertight and cost-effective strategy for the coating of the Transrapid guideway.

Coating machine runs at 25 meters per minute along the high-speed track

The central element for the planned coating mission was a mobile coating robot specially developed for this purpose. The fully autonomous, remote-controlled unit was served by a tailor-made supply car (6.5 t live load) in front, carrying all the necessary supply equipment and the robot`s remote control. The coating machine, on which two spray boxes with spray nozzles were installed directly above the skid strips, was driven by two speed-controllable drive chains that were positioned over the lateral guide rails on both sides of the Transrapid guideway and there received the necessary push from additional fixed magnets. The paint spray pumps, compressor, power pack and robot remote-control were accommodated on the supply car in front, which was also electrically driven. Rummel is particularly proud of the rapid technical implementation of the strategy: "Although it had never been built before, the complete machine was up and running within two weeks. This must be a world record."

During the coating process, the thickness of the four coats was constantly monitored so that the demanded consistently high quality was assured. But this was not all: After the coating system had been applied, the PeinigerRöRo experts controlled the quality of their work again with spot checks of the adhesive strength and film thickness of the dry coating.

Dual benefits

The efficiency and versatility of the coating strategy was then underlined during the performance of the second task: The coating robot underwent minimum modification so that it could apply the heat-absorbent coating between the two skid strips. For this, the robot`s two side spray boxes were removed and replaced with a continuous spray bar with a total of five nozzles. The application of the heat-absorbent coating also went off smoothly, and in only 90 days 30 metric tons of material had been applied to about 20,000 m² of guideway surface.