Fig 2: Lube oil of ‘Differential’ of five dumpers


colour change of lube oil (discoloration, darkening of colour) is observed. This would prevent sudden breakdown, reduce productivity loss and save money.


Fig 3: Lube oil of ‘Final Drives’ of the track type tractor


Service technicians must take informed decisions based on these data to prevent premature failure of components. Gears & roller bearings (Fe & Cr) must be thoroughly inspected for scratches, pitting & spalling and accordingly further actions must be taken. Dust ingression points (seals, breathers, filters, fresh oil) must be identified and necessary actions must be taken. Lube oil must be kept clean. Filtration systems must be upgraded if necessary. All these follow- up actions will help increase component life and huge savings can be achieved at the end of the day.


Conclusion From the above facts it is clear that this is a common phenomenon. This can happen for different machines or in a same machine for two final drives or two differentials or even two wheel bearings.


These particles are fine rubbing particles when observed under a microscope. These small sharp particles have a tendency to create occasional large particles which initiate the fatigue wear mode. Silica along with wear debris promote abrasion followed by fatigue or abrasion and fatigue to proceed simulta- neously. When the above pictures are correlated with oil analysis data, it may be clearly concluded that when silica or metal content in the oil increases, the colour darkens as demonstrated in Fig.4.


At any such construction or mining site, particularly where there is a fleet of machines, visual inspection and condition monitoring play a very crucial role.


Service technicians or supervisors must delve deep whenever any abnormality in


Table 1: FDRL & FDRR are final drive real left & rear right respectively. Metal contents are in parts per million (ppm), oxidation in %.


References 1. The basics of used oil sampling, Jim Fitch & Drew Troyer, Practicing oil analysis magazine, September, 2004


2. Caterpillar SOSSM Services, Media No. PEDP 7036-04


3. Lubricants Analysis: Back to basics, Part 3, D Mukherjee, Lube, Issue no. 66, April, 2005


4. Oil analysis basics, Drew Troyer & Jim Fitch, Noria Corporation, Tulsa, Oklahama, USA


5. Airing out oxidation, R N Wurzbach, Practicing oil analysis magazine, May, 2000


6. Lubricants Analysis: Back to basics, Part 1, D Mukherjee, Lube, Issue no. 64, December, 2004


7. Handbook of lubrication, vol 2, Theory & practice of Tribology, CRC Press Inc, 1984


8. Understanding Ferrous Density, Ashley Mayer, Noria Corporation, Practical Oil Analysis Magazine, September 2008


9. Basic wear modes in lubricated systems, Bob Scott, Machinery Lubrication, July, 2008


10. Using oil colour as a field test, Practicing oil analysis magazine, November, 1998


EMAIL debasish.mukherjee@tiplindia.com


Fig 4: Root cause – explanation of observed facts


Biographical profile Dr Debasish Mukherjee


Education


Graduate in chemistry in 1976 from Burdwan University; Post graduation in pure Chemistry from IIT (Indian Institute of Technology) Kharagpur in 1978; Doctorate in Chemistry from IIT Kharagpur in 1985.


Service


1986-87 post doctorate fellow at University of Salford, Manchester, UK. 1987-91 senior research fellow at IIT Kharagpur in sponsored projects. 1991-99 British Oxygen India (BOC India Ltd) working on application of gases. 1999 to present date TIPL (Tractors India Pvt Ltd, dealer of Caterpillar Inc, US) as a senior manager, condition monitoring and contamination control.


Contamination control auditor certified by Caterpillar, US.


Publications


Thirty papers and articles have been published so far out of which 26 are in international journals of repute. These include research papers, review articles, teaching modules, articles in interna- tional conferences and magazines.


EMAIL


debasish.mukherjee@tiplindia.com conditionmonitoringoil@gmail.com


LUBE MAGAZINE No.103 JUNE 2011


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