# Diagnosing the Machine Set Rotor Using Its Relative Vibrations
## 8 Conclusions  
1. From the point of view of maintenance, it is justified and technically possible to distinguish the \"machine set rotor\" as a functional unit in the driving machine-driven machine set found in production and propulsion systems. It is possible to create the model of a machine set rotor. 2. Friction moment can be considered as one of the substitute wear margin measures of the machine set. Changes in the friction moment result in measurable changes in the rotor torsional vibration acceleration. 3. It is possible to identify (substitute) wear margin qualities in the driving machine-driven machine set. The qualities describing the wear margin of the machine set rotor should include alignment, unbalance and transfer function of the machine set rotor. In a machine set rotor supported by slide bearings, the machine set rotor alignment and unbalance have an impact on the value of the position of the journal relative to the shell in the case of radial bearings and the position of the shaft flange relative to the axial bearing shell. The position of the journal and the position of the flange relative to the corresponding shells also depend on the wear margin of the given bearing, which means that the wear margin of the bearings affects the alignment of the machine set rotor. If the machine set rotor has a crankshaft, the deflection of shaft cranks is a measure of crank alignment. The deflection of cranks causes axial displacement of the crankshaft end frontal surface during the rotation. The (substitute) wear margin measures of the machine set rotor can change in the measure of journal or flange position relative to the corresponding shells and measures of cranks deflection or measure of axial displacement of crankshaft free end. 4. It is possible to identify the (substitute) wear margin measure of the radial and axial slide bearing. They are (for the radial slide bearings) the dimensionless Sommerfeld number and (for axial slide bearings) the bearing load capacity (the number \(B_{k}\)). For radial bearings--the eccentricity of the journal in the shell, while for axial bearings--the distance between the shell and the flange can be used as wear margin symptoms. 5. During the machine set operation, changes in the crank deflection cause measurable changes in the axial vibration of the free end of the crankshaft. Changes in the eccentricity of the radial bearing cause measurable changes in the radial rotor vibration measure, and changes in the distance in axial bearing result in measurable changes in the axial rotor vibration measure. 6. The desired measures of axial vibration of the free crankshaft end are an average value, amplitude and phase shift of the displacement waveform. Because the average value of the displacement of the free end is affected by the displacement of the whole rotor within the axial bearing clearance, simultaneous measurement of the average value of axial displacements in the axial bearing is required. 7. The radial vibration in radial bearing can be measured as the trajectory of the journal center. The desired measures of radial rotor vibration are a distance between the average value of the journal center trajectory and the center of the hole for the bearing shell. The distance can by measured by means of a calibrated sensor head. 8. The desired measures of rotor axial vibration are an average value of the rotor vibration displacement measured in the thrust or the position bearing by means of a calibrated sensor head. 9. For a machine set rotor with crankshaft supported by slide bearings, it is justified and possible to build a position head of the machine set rotor and to find a method of position head calibration. 10. Free crankshaft end head, i.e., the free end head with a Ferraris sensor, displacement sensor and shaft angle sensor with a converter can be used to measure the synchronously averaged waveform and spectrum of the machine set rotor torsional vibration acceleration and axial vibration displacement. 11.