Case Study: Vibration monitoring for planetary gearbox in vertical axis coal mill

Bagus Catur Pamungkas, Senior Maintenance Engineer, PT Vale Indonesia


Vibration monitoring is one of the most important methods to detect and diagnose faults in gearboxes. Planetary gearbox in vertical axis coal mill experienced high impact load and severe working condition that increase wear and shorten usage life. Existing vibration monitoring system based on overall vibration levels repeatedly causes false trips and inaccurate for in-depth analysis. To avoid costly downtime more accurate vibration monitoring is required.

This presentation will describe our strategy to improve vibration monitoring for planetary gearbox in vertical axis coal mill using spectrum analysis. Vibration analysis for planetary gearbox is more complicated than fixed shaft gearbox because planet gears mesh simultaneously with both the sun gear and the ring gear. Planetary gearbox consist of sun gear, planet gears and ring gear. A sun gear rotates around a fixed center, planet gears rotate and revolve around the center of the sun gear, and ring gear is typically stationary. Characteristic frequency associated with gear failure in planetary gearbox is calculated based on gear parameters and input speed. Characteristic frequency developed for all potential gear damage: single defect on sun-planet-ring gear tooth surface and distributed pitting on every sun-planet-ring gear tooth.
1. Overview of vibration monitoring in planetary gearbox
2. Application of spectrum analysis for planetary gearbox to detect gear fault
3. How to calculate characteristic frequency associated with planetary gear failure


Bagus Catur Pamungkas currently works as Senior Maintenance Engineer for Vale Indonesia. He has over 13 years experience in mechanical engineering and maintenance industries. He holds bachelor degree in mechanical engineering from Institute of Technology Bandung in Indonesia and also certified Project Management Professional from Project Management Institute.