At the Palm paper factory, located in Aalen in Baden-Württemberg, nine paper machines in five factories annually produce approximately 2.2 million tons of newsprint and corrugated base paper. Correspondingly high are the demands from the double-girder bridge cranes that have been in. “The cranes are in use day and night,” says Sven Bohrer, electrical engineer at the Palm paper factory. “If one should break one day, the production would have to stop, or at least greatly slow down, until the problem is solved. This would cost us time and money.” For this reason, Konecranes has closely investigated the gear oil of the hoisting gears. For the oil analysis at Palm, Konecranes experts took samples from the hoisting gears of the eight double-girder bridge cranes. “The samples are analyzed by our laboratory, which specializes in industrial drive train analysis. Here, the lab staff compares the current state of the oil with the samples taken in 2016 and against the OEM design limits,” says Nico Zamzow. “This way, we also use trend analysis to provide the best possible picture of any change within the condition of the gearbox.” The result for Palm: Seven of the eight cranes were found to be “healthy”, as in the gear oil contained few to no foreign elements or waste substances indicating contamination or wear. However, the gear oil of the automated number 5 crane, used in the roll warehouse, was found to have a noticeable increase in its wear partial count, triggering the lab to issue a “Caution” notification on the analysis report.
If the reason for the wear is not clearly identified and removed, the gear may be permanently damaged. “If the gear is jammed while there is a roll on the hook, it becomes very difficult to recover it and repair the crane,” explains Nico Zamzow. In order to determine whether there is already damage, the Konecranes experts used the Crane Reliability Study (CRS). The modular analysis allows them to check safety-relevant components, such as the hoisting gear as well as the steel structure, the motors, and the electrical equipment of the crane. In the case of Palm, Konecranes used a high-definition video endoscope. “Just like in medicine, we use the endoscope to reach inaccessible places without having to dismantle the entire gear,” says Nico Zamzow.
Following the investigation, the Konecranes experts are certain: The hoisting gear must be replaced. In addition, the cable drum, the cable drum support, the slip-ring unit, the cylinder coupling, and the motor coupling must be renewed. “Thanks to discovering the wear early on, there was no risk to safety and we were able to replace the old gear with a new one without affecting production,” explains Nico Zamzow.