Is the vibration known as the "belt rate" higher or lower in frequency than the running speed of either pulley/sheave?

The "belt rate" refers to the frequency at which the belt moves as it passes over the pulleys or sheaves. This frequency is determined by the rotational speed of the pulleys and the diameter of these components. Since the belt wraps around the pulleys, each time the belt travels the circumference of a sheave, it contributes to the overall vibration frequency induced by the system.

In a typical belt drive configuration, the running speed is the rotational speed of the pulleys, which is influenced by their diameters. The belt rate is generally a lower frequency compared to the frequency of the running speed of the pulleys. This is because the belt vibrational frequency is a function of both rotational speed and belt length, which often results in the belt not keeping up with the rotational frequency of the pulleys. As the belt has to travel a greater distance than what a single rotation of the sheave implies, its frequency is lower than that of the running speed of the sheaves themselves.

When analyzing vibration and frequency in belt-driven systems, it becomes essential to recognize this relationship, as it aids in diagnosing issues related to belt performance, wear, and potential misalignment, ultimately facilitating maintenance and operational efficiency.