The effect of an extreme pressure additive on the tribological behaviour of steel rollers with surface irregularities

Fin Lin Jen Fin Lin, Hour Horng Jeng Hour Horng, Yang Lee Ke Yang Lee

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1 Citation (Scopus)


Experiments were conducted utilizing a gear-cam adapter to simulate line-contact wear. The rollers, which differ in asperity heights and roughness patterns; were riding on the roller plates and sliding over the flat plates of the lower specimen. The effect of the P-type extreme pressure (EP) additive in the oil in conjunction with the roller's roughness parameters on the tribological behaviour was investigated under different applied loads. The experimental results reveal that the roughness pattern and applied load are two essential factors governing the friction coefficient. When a phosphorus additive was used, the roughness pattern affects the friction coefficient only under higher loads. The friction coefficient produced by the smooth rollers (0.2 μm) or by rollers with the longitudinally oriented pattern or the oblique pattern under a high load (1779.2 N) is lower than that produced by the medium load (889.6 N) or even the small load (444.8 N), but the friction coefficient produced by the roller with the transversely oriented pattern increases with increasing applied load. The oil temperature does not seem to have a clear relationship with the roughness pattern under examination but is much affected by the applied load. The oil temperature of the steady state substantially drops on using the EP additive and working under a high load. Increasing the asperity height of the rollers always raises the wear rate. The existence of the EP additive possibly enhances the wear rate unless the applied load is sufficiently high. The antiwear performance of the EP additive is depressed until higher loads when the contact surface possesses a smaller asperity height. The appearance of wear resulting from the use of the EP additive shows that the surface damage of the rollers is substantially reduced.

Original languageEnglish
Pages (from-to)107-118
Number of pages12
Issue number1
Publication statusPublished - 1993 Oct 1

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


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