Abstract: A thermal-partial elastohydrodynamic lubrication theory is used to study the surface flash temperature of the quasi-steady state spur gears in this paper. By solving simultaneously average Reynolds equation, nominal film thickness equation, energy equation, asperity contact temperature equation, etc., the effects of surface topography parameters such as surface texture orientation and surface roughness and other operating condition parameters on the flash temperatures in the oil film layer and on the gear teeth surfaces in the meshing cycle are analyzed. The calculation results in current work show that the surface flash temperatures of involute gears increase with the increases of surface texture orientation value and surface roughness root-mean-square value, and that in the arc of action, the maximum temperature rise appeares at point A where the tip of a driven tooth touches the flank of a driving tooth. The research method adopted in the paper are fo some significance to the study of gear scuffing mechanism and the study to increase the gear scuffing load carry capacity.

Key words: gears, elastohydrodynamics, surface roughness