Two Minute Tips  

Bucket Wheel Drive Train

Hiren Limbachiya
Hiren Limbachiya | Regional Manager, ONYX InSight

In the mining industry reclaimers are used at stockyards and ports, as materials handling equipment for loading trains and ships. These are critical equipment for maintaining throughput and a severe break down can easily run into millions of dollars of lost revenue and should be avoided. A failure in the bucket wheel bearings or drive units can put the reclaimer out of service for many days.  If a developing fault in the bearing runs undetected it may result in collateral damage, such as a cracked bucket shaft. Condition monitoring techniques like vibration analysis and oil analysis are in use to detect these faults and proven to be useful. However, there are challenges and limitations with current practices, that can be addressed with recent technology advances.

Current Challenges

  • Slow and variable speed – The bucket wheel runs at around 5-6 RPM and the speed varies as bucket wheel approaches and leaves the stockpile bench. This operating condition requires a vibration system to have the “smarts” to deal with slow and variable speed data.
  • Gearbox inboard bearing frequencies and bucket wheel drive end bearing frequencies are often similar and make it hard to pinpoint the fault location if either bearing develop the fault. Improving frequency resolution and other methods can help isolate the location.
  • Bucket wheel bearing fault frequencies are below 2 Hz, without the correct selection accelerometer low-frequency range and sampling parameters, these frequencies won’t be evident within the signal.
  • Data collection with a portable analyzer is difficult to do well in the environment, without a highly skilled and patient VA.

Remedies

  • Order tracking is required for variable speed and needs to be carefully designed.
  • Use of early detection techniques like demodulation and enveloping with correct filters are highly recommended to detect slow speed bearing faults.
  • Waveform parameters should be appropriate to collect all necessary information along with a good resolution for spectrum.
  • Current ICP accelerometers’ low-frequency response is limited, and this can be resolve with advanced MEMS accelerometers which can respond well down to 0 Hz. They have can be advantaged by being triaxial with temperature without any additional production cost.
  • Incorporate an online condition monitoring system with order tracking functionality and smart triggering. This can be also useful to save time on data collection. They are easily configured to collect multiple sets of data during a day and provide good reliable trends. With correct fault alarms, it is easier to analyze the data and plan corrective actions in time
  • Adding online oil sensors into the same vibration data acquisition system allows for closer monitoring of the drive units.

The above remedies are more likely to address current challenges for fault detection using condition monitoring techniques. This frees up time for the skilled technician to solve other problems on the equipment.

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About the Author

Hiren Limbachiya
Hiren Limbachiya Regional Manager, ONYX InSight

As a Regional Manager – ANZ at ONYX InSight, Hiren’s primary role includes leading Sales, Engineering and Operational activities for the region. His background includes Degree in Instrumentation Engineering and Project Management, coupled with experience around asset reliability, primarily focused in the mining and industrial environment and recently in the wind industry.