## 3 Results and Discussion
### Vibration Analysis
From the obtained results and data analysis, it can be stated that the average values of the vibration velocity (in the frequency interval of 10-1000 Hz), in combination with other measured parameters, can be used to assess the combine threshing drum's bearing condition. For the study, combine threshing drum bearings with an output of 3590 MH were used. Measurements were taken using the same methodology as for testing new bearings. After performing the analysis using the vibration response spectrum, significant changes in bearing defect frequencies (25 Hz, 101 Hz) were observed (Figure 12). After comparing the theoretically calculated defect frequencies (the defect frequency of the outer ring (f-RPI) was 118 Hz, the inner ring (f-RPV) was 175 Hz, and the rollers defect (f-RDD) was 45 Hz. ), it can be stated that the studied bearing vibrations were caused by a defect of the outer bearing ring. When analyzing the RMS values, these values should be as close to zero as possible. Figure 13 shows that the RMS values of the assessed bearings in the range up to 6000 Hz reached 0.188 g (RMS), which indicates insufficient bearing stability. To prevent threshing drum failure in the combine, it is recommended to replace the bearing with a new one, or to have it additionally checked by another diagnostic method. A microscope was selected to check the condition of the used bearing again. Before disassembly of the threshing drum bearing, the vibrations produced by the bearing were measured in a running combine. In addition, a smart 5 MP PRO digital microscope was used to identify existing bearing defects after bearing dismounting. The resulting visual material is presented in Figure 14. The image of the used bearing (Figure 14a) clearly shows the surface damage. The damage is presented by cross lines in the inner ring. The inner ring defect determined by the vibration analysis method has been proved by microscope image (Figure 14a). Comparing the microscope image of the new bearing (Figure 14b), the surface of the inner ring is smooth and of good quality. Figure 12: Bearing vibration spectrum. In summary, utilizing the bracket developed in this paper, vibration instrumentation could be used for diagnostics of the bearing conditions of agriculture machines, without dismounting the bearing. If the measurement values are in green, the bearing is still suitable for use. If the value of the bearing is in red, they are at the limit values of vibrations. In this case, the bearing must be changed. The investigated threshing drum bearing with an output of 3590 MH possibly could be used for a significant period of time. Therefore, even small defects in the bearing could cause a breakdown of the combine harvester requiring several hours to repair. During this breakdown time, a typical combine harvester could harvest from 24-30 ha [28]. Therefore, changing the bearing before a breakdown occurs can reduce unexpected expenses. Timely replacement of the bearings ensures smooth combine harvester operation during the season. At the same time, bearing vibration tests make it easier and simpler to evaluate the bearing condition of combine harvesters and other agricultural machines under standard operating conditions. Further, the change of the bearing is not a significant effect. Figure 14: Bearing surface view of the inner ring. **(a)** View of the used bearing inner ring; **(b)** view of the new bearing inner ring. Figure 13: Bearing vibration spectrum in the range of 0–12,000 Hz. vibration energy exerted could be used for delamination defect analysis of the bracket in future investigations [29].