The influence of dissolved refrigerant HFC134a on oil film formation and wear performance of oils was investigated using a ball-on-type tester in a reciprocating motion. Oil viscosity considerably decreased by dissolving HFC134a and the extent of reduction in viscosity was affected not only by HFC concentration but also by the mean molecular weights of the oils. The reduction in oil viscosity by dissolved HFC134a brought about increase in wear amount. The oil film formation in a reciprocating motion was affected by the stroke length. In the present tests, by reducing the stroke length from 5 mm to 3 mm, the oil film formed in an initial stage became smaller, and finally collapsed. The oil collapse was happened when the cavitaion which generated in the vicinity of stroke center remained at the stoke ends.
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