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Application Note

Oil Debris Sensor prevents mechanical breakdown of speed reducer

Oil Debris Sensor detects early signs of component breakdown in speed reducer preventing mechanical failure and avoiding costly downtime

Gill’s oil debris sensor has been installed into a leading multinational engineering manufacturer’s speed reducer gearbox to detect metallic particles directly affecting the gearbox condition.


The widely recognised manufacturer required a reliable solution that would alert the machine operators of potential maintenance issues before catastrophic failure occurred. The company had been using vibration monitoring techniques, which had proven insufficient in detecting faults early enough to prevent downtime.


Gill’s debris sensor was fitted into the bottom of the reducer drain sump to monitor the accumulation of circulating ferrous metallic debris to improve the mechanical failure rate and maintenance of the system.

The sensor features solid-state induction technology to determine the amount and magnitude of debris build-up to a high degree of accuracy. Using a strong internal magnet to attract ferrous particles to the sensor’s face, both fine and coarse debris can be detected inside the reducer’s lubrication system.

The inductive sensor is operational in temperatures from -40°C to +150°C providing operators with unprecedented real-time collection of contamination and debris data inside the reducer.

Two independent output channels are provided by the sensor, one (configured to a 2.25-4.25V output) to relay fine particle build-up and the second (0.5-4.25V) for large coarse particles. Each output channel gives a consistent voltage reading. When debris is detected on the sensor’s tip the voltage output increases proportionally to debris collected. These two independent channels provide engineers with an accurate insight into the ferrous wear contamination condition of the lubricant, indicating when the oil requires changing, and the earliest indication of component breakdown, enabling a preventative maintenance intervention before complete component failure and unplanned downtime.

Regular inspection of the sensor’s data readings alerted engineers of a large amount of ferrous particles collected on the sensor. On inspection gear flaking and cracking were found, caused by the early failure of a supporting roller bearing. As a result of the sensor’s early detection, the operators were able to shut the machine down in a controlled manner, during a planned maintenance period, to replace the damaged components. 

This swift analysis and action prevented a costly mechanical breakdown and it is estimated that the cost saved was sufficient to cover the cost of the full trial installation.

Using the real-time data monitoring provided by the debris sensor, the company were able to take quick action when the debris level increases. The installation of the sensor has successfully reduced the mechanical failure rate and improved the overall condition of the speed reducer gearbox.

“As a result of the fast detect, we were able to prevent a breakdown that otherwise would have resulted in big trouble” says a company representative. “Installing a wear debris sensor is a good case for maintaining the speed reducer in the future”

The company has now placed orders with Gill to cover all of their other similar speed reducers and has a planned roll out program to fit Gill oil debris sensors to other machines in different areas of their manufacturing sites. 

Oil debris sensor with build up