A study on the mixed lubrication characteristics of journal bearing for high-speed planet gears in tracked vehicles

In this paper, the feasibility is explored of using journal bearing as the sliding support of the planet gears of planetary transmission in tracked vehicles under high speed condition. A solid lubrication bearing with polytetrafluoroethylene composite is selected. Based on the average flow model and the asperity contact theory, the effects of surface roughness, inflow oil temperature and relative clearance of bearing on its lubrication performance are analyzed. The results show that the bearing material selected meets the operation requirements of high-speed planetary mechanism. With proper clearance and surface roughness selected, both the mixed lubrication at low speed and the hydrodynamic lubrication at high speed can be realized. It is recommended by analyses that the surface roughness should not exceed 0.8μm and the relative clearance should not be smaller than 0.0015 in design, and the temperature of inflow oil should be controlled to a level as low as possible for good performance.