## 3 Description of the Investigated Problem
### Characteristics of the Diagnostic Methods Applied  
Lubricating oil analyses:  
* ppm Fe abrasive particles were evaluated. The following were applied to assess vibrations in the low frequency range:
* Velocity measurement method (jitter speed), [mm/s] unit, RMS detection.
* According to the ISO 10816-3: 2009 recommendation, FFT (Fast Fourier Transform) spectrum for the frequency range 10-800 Hz.
* Enveloping Acceleration measurement method (method of measuring vibration acceleration in the high frequency range up to 10-20 kHz, through which the condition of roller bearings and gears is assessed), gE unit, PtP detection, for the frequency range 50-1000 Hz, FFT spectrum and time log. The following were used to assess vibrations in the high frequency range:
* (Jitter) acceleration measurement method, g unit, PtP detection, frequency range up to 16 kHz, FFT spectrum and time log
* Enveloping Acceleration measurement method, gE unit, PtP detection, frequency range up to 10 kHz and up to 20 kHz, FFT spectrum and time log. Diagnostic assessment methods in the field of acoustic emission and ultrasound:  
Figure 7: View of the stand in configuration B.  
* SEE (Spectral Emitted Energy) measuring method--acoustic emissions (SKF), See unit, PtP detection, frequency range up to 600 kHz, FFT spectrum and time log.
* HFD measuring method--high frequency detection method (SKF), analysis of oscillations (accelerations) in the frequency range 40 kHz.
* Measuring method is used to assess lubrication, carrying capacity of oil film, metal contact, seizure, abrasion of contact surfaces (bearings and gears).  
The so-called bump test was done on the BR--the search for natural frequencies of the measured system in the torsional and tipping direction. This is a traditional method of measurement. Performing a bump test involves the use of at least a two-channel frequency analyzer, impact hammer and accelerometer.  
During the measurement, the LR TS 050 was fixed to the diagnostic equipment frame with screws. A mechanical arm with a weight of 2.5 kg was attached to its outlet flange. The excitation force was generated by the excitation impact hammer at the location of the weight at the end of the weight arm.  
During the bump test, the oscillation amplitudes and frequencies are monitored by accelerometers and displayed as the area of the amplitude-frequency dependence. The most important information obtained is in the frequency deviations of the LR structure at their locations, and to a lesser extent, the attenuation values associated with these modes.  
Subsequently, the BR was measured at a constant rotational frequency of 1000 rpm at the input at a sinusoidal load (weight on the arm) in both directions of rotation (CW, CCW). The vibration sensor, PBC 356B18, was placed on the support body of the gearbox (in the vertical direction). At the same time, a repeated measurement of the start-up ramp was performed--the measurement of absolute vibrations during a continuous change of speed at the input, in the range of 0-2000 rpm and 0-3000 rpm. The aim of this measurement was to compare the effect of the onset of resonant events--amplification of the output arm vibration. Vibration sensors were placed on the output arm, at the point of the weight, in the radial and axial direction.  
Temperature measurement was done on the BR in order to monitor temperature changes (BR heating) during the trial run process.