Optimizing the lubrication performance of standard involute spur gear with parabolic profile modification is investigated in this paper.Via tooth contact analysis

the principle of gearing and the theory of elastic hydrodynamic lubrication are combined to compute the lubrication performance of modified gear.The average lubrication performance in a mesh period is used as objective criterion.The start radius of profile modification

the amount of tooth tip relief

and the shape of parabolic modification curve all can be optimized.By analyzing the numerical results

some conclusions are drown.