Abstract
There have been a number of issues concerning the sliding characteristics of oil-impregnated sintered bearings caused at the temperature below freezing. However, the relationship between bearing design parameters and tribological characteristics below freezing has not been clarified yet. In this study, we experimentally investigated the coefficient of friction and separation degree between the oil-impregnated sintered bearing and the journal operating at below-freezing temperature. As a result, the following factors were found as the influence of the ambient temperature to the friction characteristics of the oil impregnated sintered bearings. One is that, in below freezing conditions, the friction coefficient μ increases along with the increase of Sommerfeld number (S). In addition, if the value of S is the same (1.e. the viscosity is the same), the coefficient becomes smaller as the ambient temperature lowers. The other is that the friction characteristics in below freezing conditions are influenced by the increase of the lubricating oil viscosity due to the temperature decrease and the permeability of the bearing. Depending on a balance between them, the ambient temperature has different effects on the ju-S curve.
