Influence of Contamination of Gear Oils in Relation to Time of Operation on Their Lubricity

Leszek Gil,Edward Kozłowski,Daniel Pieniak,Krzysztof Przystupa,Konrad Gauda,Katarzyna Antosz,Paweł Izdebski

doi:10.3390/app112411835

Abstract

The quality and reliability of consumables, including gear oils, results in the failure-free operation of the transmission components in heavy trucks. It is known that oil viscosity is essential for all lubricated tribopairs for wear and friction reduction in all vehicles with a gearbox. Viscosity may be influenced by the contamination that wear products can impart on the oil. Oil contamination can also affect lubrication efficiency in the boundary friction conditions in gearboxes where slips occur (including bevel and hypoid gearboxes). The present research focused on this issue. An obvious hypothesis was adopted, where it was theorized that exploiting the contaminants that are present in gear oil may affect how the lubricating properties of gear oils deteriorate. Laboratory tests were performed on contaminants that are commonly found in gear oil using the Parker Laser CM20. The study was designed to identify a number of different solid particles that are present in oil. At the second stage, friction tests were conducted for a friction couple “ball-on-disc” in an oil bath at 90 °C on a CSM microtribometer. The quantitative contamination of the gear oils that contained solid particles and the curves representing the friction coefficients of fresh oils with a history of exploitation were compared. The test results were statistically analysed. Exploitation was shown to have a significant impact on the contamination of gear oils. It was revealed that the contamination and the mileage had no effect on the tested oils.

Highlights

Ensuring that machines and devices are able to conduct high-quality work and maintain operational reliability is a very important issue in chemical applications [1,2,3], e.g., transport [4,5], electronic systems [6], or scientific works, e.g., for chemical purposes [7], it is of great importance for applications that are related to the production of high-quality food products [8]
Load transfer occurs through a layer of grease that is generated by the hydrodynamic effect in the machine kinematic nodes that are under increasing motion [12]
High pressure in the contact area increases the viscosity of the lubricant as well as the elastic deformation of the surfaces that are in contact with each other indirectly through the lubricant film

Summary

Introduction

Ensuring that machines and devices are able to conduct high-quality work and maintain operational reliability is a very important issue in chemical applications [1,2,3], e.g., transport [4,5], electronic systems [6], or scientific works, e.g., for chemical purposes [7], it is of great importance for applications that are related to the production of high-quality food products [8]. High pressure in the contact area increases the viscosity of the lubricant as well as the elastic deformation of the surfaces that are in contact with each other indirectly through the lubricant film. This is the case for elastohydrodynamic lubrication. As stated in [18], high pressure in the contact area increases the viscosity of the lubricant and the elastic deformation of the contact surfaces in an indirect way through the lubricant film. It is known that the formation of a lubricating film in oil is intended to prevent metal surfaces from coming into direct contact with each other, but it refers to a situation in which wear and high friction occur between sliding surfaces. It is for this reason that periodic oil changes are performed [15]

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