Abstract: Aiming at the bearing capacity problem of NN type involute planetary reducer with small tooth difference, the experiment on the bearing capacity of the prototype was carried out on the load test-bed of the reducer. 
The double gear in the transmission system of the reducer was seriously eccentric, in order to improve the load-bearing condition of the double gear, the virtual simulation analysis of the tooth surface modification and load of the double gear was carried out by using the gear modification method. The unit length load of the tooth surface of the double gear was reduced, the uneven distribution of the tooth surface load and the location of the tooth surface contact spot of the double gear were improved, and the transmission accuracy of the double gear was improved. Then, the modified prototype was manufactured. Finally, the experiment was carried out on the load test-bed of the reducer. After modification, the experimental results show that the reducer has high bearing capacity, but the double gear has serious eccentric load phenomenon in its transmission system. Under the same experimental conditions, the contact spot on the tooth surface is located in the center of the tooth surface, and there is no wear on the tooth surface, which improves the load distribution on the tooth surface, reduces the load on the tooth surface, and improves the bearing capacity of the reducer.

Key words: small tooth difference planetary reducer;load capacity;eccentric load of gear;gear modification