Belt-Driven Fan Pulley Misalignment and Unbalance Case

We recently carried out a vibration analysis for one of our customers on a belt-driven fan. Initial measurements showed very high axial vibration at both the motor and fan drive end, with dominant 1X running speed components – strongly indicative of pulley misalignment. In addition, the fan side also exhibited high 1X vibration, pointing to unbalance.

Upon inspection, the alignment was found to be significantly out. We stopped the machine, realigned the pulleys, and inspected the fan impeller, which had a large amount of build-up. The impeller was cleaned, the pulleys and belts were inspected, and it was great to confirm that both were still in good condition with no visible wear.

After completing the corrective actions, we re-measured the vibration levels. The results showed a dramatic improvement, with vibration dropping from 23.0 mm/s RMS down to 1.2 mm/s RMS.

While this may not seem like a significant achievement, being able to identify the problem, take corrective action, and see the results immediately builds confidence in your work. More importantly, it earns the customer’s trust and reinforces your own confidence in your ability. This is how you win more work, step forward, and let your results speak for you.

belt fan misalignment unbalance