Calculation of Tooth Surface Contact Stress and Tooth Root Bending Stress of the Asymmetric Gear with Double Pressure Angles Meshing Beyond the Pitch Point Based on Friction Between Teeth

Advantages of asymmetric gear include larger load carrying capacity, smaller vibration and longer life. The vibration of the gear system due to the change of the direction of the friction force can be avoided when meshing beyond the pitch point happens. But the meshing mechanism of asymmetric gear with double pressure angles meshing beyond the pitch point is not yet known. In this paper, the basic theory of the asymmetric gear driving system meshing beyond the pitch point is developed. Through analyzing the forces exerted on the driving gear of reducing-speed asymmetric spur gear drive system meshing beyond the pitch point in single & double pairs teeth meshing range, the contact stress and bending stress on the pinion under the action of the sliding friction between teeth are derived. It will be seen that the contact stress and bending stress of asymmetric gear drive system meshing behind the pitch point are lower than those of the symmetric gear drive system meshing behind the pitch point, under equal conditions. And the contact stress can be effectively reduced by tuning the pressure angle of driving side, modification coefficient on pinion, the modulus and the addendum coefficient on the coast side.