Belt Driven Fan Vibration

This vibration pattern is not typical for a belt drive.

Belt driven fan vibration.

It can be confirmed by measuring phase in the axial direction at fan speed. When it is present the vibration at fan speed is typically the highest vibration peak in spectra taken on the motor. Problems due to the shafts or pulleys misalignment eccentricity etc cause vibration at 1x rpm of the component with the problem i e. Fatigue type failure in fan components due to continued exposure to abnormal loads or vibration.

Both axial readings were in phase at running speed as determined by cross channel phase readings. Vibration analysis is a condition monitoring test which is widely applied for determining the operating condition of any rotating machine for example centrifugal fan. Belt drive problems and drive misalignment. The axial vibration levels were high but slightly different on each bearing.

It is important to realize that some of the belt drive vibration problems listed above do not cause vibration at belt related frequencies. Eccentric pulley on the fan causes vibration at 1x rpm of the fan. Sheave misalignment is a very common problem with belt driven fans. Belts along with electric motors shafts and pulleys are a critical component of power transmission in belt drive systems.

Most vibration was at the fan shaft rotational frequency. While belts require very little maintenance improper belt tension misalignment of pulleys mishandling of belts and environmental factors are common problems that can shorten the life of your belts and bring your system to a halt.