Lubrication and maintenance of thrust ball bearing in bucket wheel excavators

Bucket wheel excavator is a sample of industrial application in Serbian thermal power sector. The circular motion of the excavator is done through a thrust ball bearing and the drive via toothed ring. This thrust bearing, can perform both slewing (oscillating) movements as well as rotational movements and therefore is commonly named as a slewing bearing. The authors describe lubrication and maintenance of the machine under the real conditions with a goal to rich minimum of friction and wear during its operation. The slewing bearing is probably the most important driven unit of the machine, which is grease lubricated by pump with nozzles that are arranged on its perimeter. Once the rolling trails damages are detected, the entire track has to be replaced. The replacement is a standardised procedure, where bearing segments are one by one dismantled with consequent diagnosis and scanning. Lifetime of this assembly strongly depends on the quality of greases, incl. their contamination, on the tightness of the assembly and requires the warrantable monitoring intervals. The results and analysis could be used for better prediction of the bearing life in terms of lubrication quality and working regimes of bucket wheel excavators.