Computer simulations are now routinely used in the design and analysis of ring packs for internal combustion engines. Commonly they predict that an increase in engine load decreases minimum operating film thickness because oil availability and oil transport through the ring pack are reduced under these conditions. To assess the reliability of new simulations, investigators compare the output of computer models with experimental measurements of parameters on operating engines. Contributing to this process this paper presents an experimental study of an investigation into the effect of load on the minimum oil film thickness between piston rings and cylinder liner in a fired compression ignition engine. Oil film thickness data were collected using capacitance-based transducers located near top dead centre and mid-stroke. Experiments were performed at 2000 r/min using two mono-grade oils (SAE 50 and SAE 20) and one multi-grade oil (SAE 5W50) under a range of fixed engine loads. The experimental data obtained are discussed in the context of experimental and theoretical work published by other investigators.

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Journal bearings are widely used in heavy industry and in internal combustion engine applications. There is a need to increase the power density of various machine parts which leads to increased bearing loads and reduced lubrication film thicknesses. This type of development may increase deformations on the bearing surfaces which need to be considered in the bearing design process.The main purpose of this work was to develop a parameterized calculation model for hydrodynamic radial journal bearings which takes into account elastic and thermal deformations of the bearing surfaces. Hydrodynamic calculations were based on the numerical solving of the Reynolds equation by assuming rigid surfaces. Elastic and thermal deformations of the bearing and shaft surfaces were calculated by using the finite element method. It is concluded that elastic and thermal deformations are partly canceling each other out at the loaded side of the bearing and depending on the sliding speed and the external normal force either one of them could be more significant.