Bearings are technical devices that form part of the support of rotating axles and shafts. They support radial and axial loads applied to the shaft or axis and transmit them to the frame, housing or other parts of the structure. At the same time, they are also required to hold the shaft in space and ensure rotation, oscillation or linear movement with minimum energy loss. The quality of the bearings has a significant influence on the performance, efficiency and durability of the machine.

Nowadays, the following bearings are widely used:
• contact (with rubbing surfaces) – sliding and rolling bearings;
• non-contact (non-contact (without rubbing surfaces) - magnetic bearings.

Contact bearings are classified according to the type of friction:
• sliding bearings, where the bearing surface of the axis or shaft slides on the working surface of the bearing;
• rolling bearings, where rolling friction is utilised by inserting balls or rollers between the movable and fixed bearing rings.