Thanks to smart sensors developed by SKF, it is possible to have a direct view inside the bearing. “We can measure the loading of rollers and, by that, evaluate the loaded zone of the bearing,” Engbers says. “Furthermore, we can detect how fast the rollers are rotating or if they are sliding, and much more.
“These measurements can be compared with SKF simulation tools,” he continues, “and the measurements show a very good correlation with one another, which allows for further development of SKF’s testing and simulation competences.”
On the MSTR, the test bearing was accelerated up to 30 revolutions per minute – a milestone and currently the limit of the test rig. Faster rotational speeds directly raise the number of overrollings in the bearing, which helps to fulfil the requirements of an endurance test in a much shorter time and in turn influences cost and duration of the test regime. The ability to produce extreme speed is critical for the bearing components (e.g., cage segments). Due to the faster rotational speed, the component forces based on inertia and roller impacts to flanges and cages are increased significantly. The roller set, which is rotating at about half of the bearing speed, has a mass of 1.6 tonnes – the mass of a mid-size car. For the acceleration from 0 to 30 r/min, the MSTR is capable of applying 880 kW. As a guide, typical rotors for large wind turbines rotate at about 5 to 20 r/min; reaching the higher rotational speeds makes it possible to reduce testing times and test for extreme conditions.