PurposeThe purpose of this paper is to analyze the influence of particle motion on the lubrication characteristics. The dynamics of the particle in the lubricant is also studied.Design/methodology/approachThe dynamics of the particle is studied using Newton's second law. The particle dynamic equation is solved to determine the particle velocity, angular velocity, and location. The modified Reynolds equation is solved in couple with particle motion to determine the film pressure and velocity.FindingsThe motion of a particle suspended in the lube oil is clarified. The initial relative velocity between the particle and the fluid has a significant effect on the lubrication. For the same particle location and velocity, the larger particle or the closer distance between particle center and lower plate has greater effects on the film pressure.Research limitations/implicationsThe influence of the particle geometry on the lubrication is neglected in the study because of the small size of the particle, this neglect is idealized. Further study will take the effects of the particle geometry into consideration.Originality/valueThe paper provides the motion of the particle in the lubricant, and the modified Reynolds equation considering the particle translation as well as rotation is derived.