## 1 Introduction  
The application of High Speed Cutting (HSC) technology in machining requires, among others, machine tools with much higher kinematic parameters. One consequence of the increase in rotational speed is the greater amount of heat in the spindle rolling bearings, and thus higher temperatures. Higher temperatures mean, among other things, greater thermal deformation of the spindles and thus greater machining errors. Most of the literature reports on heat in bearings are devoted to this issue. On the other hand, the increase in temperature also affects the resistance to movement of the bearing itself. This issue will be the subject of the article. [PERSON] et al. [1] show thermal study results concerning the machine tool spindle equipped with rolling bearings and modelled with FEM. The authors focused on the influence of mounting clearances of a bearing on the shaft, and the bearing in its seating on bearing preload changes. The authors considered only hydrodynamic resistances and all other resistances determined with the traditional Palmgren model [2]. In their thermal model, they took into consideration radial deformations in the internal bearing ring and the drive shaft caused by centrifugal loads due to orbital bearing balls. [PERSON] et al. [3] demonstrate the method of electrospindle thermal modelling. It has been assumed that the heat source are the resistances resulting from lubricant and motion resistances resulting from a bearing load. The developed numerical model allows for prognoses of temperature distribution, as well as thermal deformations. [PERSON] et al. [4] illustrate a thermo-mechanical spindle model with angular bearings according to FEM. The heat was generated in bearings and motor. The experimentally verified spindle model makes it possible to predict temperature and heat distribution, as well as contact load. The article shows experimental study results in the form of an experimental model. [PERSON] et al. [5] present a dynamic thermal-mechanical model to investigate the thermal characteristics in a spindle-bearing system. In this model, transient thermal analysis, static structure analysis and calculation of the boundary conditions are conducted as a solution loop. The transient boundary conditions, such as bearing heat generation and thermal contact conductance, are calculated with the appropriate formulas. The thermal equilibrium experiment is conducted on a test rig. [PERSON] and [PERSON] [6] present a method for the computation of the power loss in angular contact ball bearings. Dynamic effects, generated at high-speed, are also included as centrifugal forces and gyroscopic moments, balls and cage interactions, ball and cage drag and churning in the lubricating bath oil. [PERSON] et al. [7] present estimation of thermal performances of angular contact ball bearings. Considering the centrifugal force, gyroscopic moment and thermal expansion, the ball loads equilibrium model was first established to analyze the bearing loads. The radial and axial heat transfer, especially the effect of structural constraints on bearings temperature, was well characterized. Compared with the presented models, the deviation between the calculation results and the test values is reduced to less than 9%. [PERSON] et al. [1] present a simulation method to establish a comprehensive prediction model for the thermal and mechanical behavior of a spindle-bearing system. By introducing a lumped element into the system, not only mechanical properties but also thermal behaviors can be predicted. In this study, three different simplified assemblies are investigated. One is the bearing inner race-shaft subassembly that includes a negative assembly clearance, and another is the outer race-housing assembly that includes a positive assembly clearance. The third is the entire system that is composed of a rolling element bearing, an inner race-shaft subassembly and an outer race subassembly. [PERSON] et al.