Regarding the bearings of the motor
Thread Content
The high-voltage variable-frequency motors produced by the Jiamusi manufacturer in this factory are available in 400KW and 800KW capacities. Why do some motors have one deep-groove ball bearing at each of the front and rear ends, while others have two NU series cylindrical roller bearings at the shaft extension end and a deep-groove ball bearing at the rear end? Which configuration method is better?
The manufacturer has surely conducted tests on what type of bearings to use; it is recommended not to change the type of bearing arbitrarily
What is the reason? Is it because the manufacturer has conducted tests?
It should have been tested for axial and radial loads, and then the appropriate model selected based on the mechanical design manual
NU cylindrical roller bearings can withstand radial loads, while deep groove ball bearings are suitable for axial loads. For motors with large rotor masses, NU bearings are used; in addition, a deep groove ball bearing is installed at each end to prevent axial movement. I’m not an expert in electrical engineering, so if there are any mistakes in what I’ve said, please correct me.
This has nothing to do with the electrical engineering field. Belonging to the mechanical category, deep groove ball bearings cannot withstand axial forces the most, as all such forces ultimately act on the cage, which is the weakest part of the bearing ； Cylindrical roller bearings have a rib, which actually allows them to withstand axial forces. These two types of bearings are used to counteract part of the axial force, which is present in any rotating device. For small motors, especially those without speed control, there are no major issues using deep groove ball bearings; however, in large motors, particularly those with speed control, it is almost never the case that only deep groove ball bearings are used on both sides.
The design usually should have one on each end, with roller bearings capable of bearing heavy loads
Deep groove ball bearings can withstand radial forces as well as a portion of axial forces. After the motor starts operating, temperature effects cause the shaft to expand; therefore, thermal stresses must be taken into account in the case of large motors. As a result, roller bearings are used at the shaft ends of large motors, as they can only handle radial forces. For small motors, where the temperature difference is not significant, deep groove ball bearings can be used simultaneously.