Case Study: Slow Speed Bearing Monitoring With Ultrasound

Chris Hallum, Regional Manager UK & Ireland, UE Systems Europe


Monitoring the condition of slow speed bearings can be a very difficult task, especially when they rotate at extremely low speeds. Using ultrasound technology makes that job a lot easier.
Because most high end ultrasound instruments have a wide sensitivity range and frequency tuning, it is possible to listen to the acoustic quality of the bearing, also at slower speeds. In extreme slow speed bearing applications (usually less than 25rpm), the bearing will produce little to no ultrasonic noise. In that case, it is important to not only listen to the sound of the bearing, but more importantly to analyze the recorded ultrasound sound file in a spectrum analysis software, focusing on the time wave form to see if there are any anomalies present.

If crackling or popping sounds are present, then there is some indication of a deformity occurring. Bearings rotating at slow speed are, in many cases, critical assets which failure can be catastrophic. In these situations, an ultrasonic instrument, or permanently mounted ultrasonic sensors, will provide maintenance teams with the data they need to correctly evaluate their condition, predict failures and avoid undesirable downtime.
In this presentation we will show, with real-life cases, how to use ultrasound for slow speed bearing monitoring, its advantages, methods, challenges and results.


1. The importance of using ultrasound together with other predictive maintenance technologies.
2. Why is ultrasound so well suited for slow speed bearing monitoring?
3. How to perform sound analysis on recorded ultrasounds from slow speed bearings.


An experienced electrical engineer with 13 years experience in the Royal Air Force. Qualifying as a technical trainer in his time, teaching many engineering principles and gaining qualifications and experience in Railway Signalling Engineering, teaching the railway engineers of the future. Highly knowledgeable and motivated, gaining Certified Maintenance and Reliability Professional status. In the past few years he has began to spread the knowledge of Ultrasound as a tool to aid in predictive maintenance strategies in every industry.