Abandoning the method of regarding the gear tooth form as the cantilever beam

this paper sets up a new method to calculate gear tooth-root stress

tooth deflection and mesh stiffness directly according to the real tooth form by the boundary element sampling calculations and the regressive analysis based on the principle of similitude. The definition formulas and new calculation formulas for transverse load factors of tooth strength and surface durability are proposed. The formulas of essential and sufficient conditions for actual double pair tooth engagement

as well as the formula of actual contact ratio

are also proposed. A new formula of contact ratio factor is proposed. Compared with the formulas in ISO6336

some problems are analyzed. The new method proposed to calculate tooth root stress doesn’t require any assumptions

is advanced in theory

simple and accurate in calculation. Therefore

the new method may replace the cantilever beam method proposed by W. Lewis. Other formulas proposed are also rather reasonable. It is suggested that the new methods be adopted in ISO 6366 standard.