Piston Ring Oil Film Thickness- The Effect of Viscosity

A Petter AV1 diesel engine has been modified to operate as a crosshead engine with a separate lubricant supply to the piston rings. Measurements of the minimum oil film thickness between the rings and the liner are presented for both mono-grade and multi-grade oils. It is shown that, at top-dead-centre, the film thickness increases as the viscosity is reduced.