The Craft Split Bearing, as any mechanical part, will generate natural frequencies while in operation; also known as fundamental defect frequency. The natural frequencies are generated by the rolling of the rollers as they pass through the load zone. The four distinct natural frequencies generated are the ball spin frequency, fundamental train frequency, and ball pass frequency for the inner and outer race. By predicting the natural frequency of a bearing, design engineers can utilize the information to avoid natural excitation and monitor for the propagation of defects as part of a preventative maintenance program.
The ball spin frequency is the rate at which a point of the Craft bearing’s roller comes into contact with either the inner or outer race. The fundamental train frequency is the frequency at which the roller cage entering and exits the load zone. The ball pass frequency is the rate at which a defect in the inner or outer race comes into contact with a roller. In the file linked below are the four equations for calculating the fundamental frequencies.