The basic theory of drum trimming is that when the inclination angle of the helical gear is the maximum, the meshing surface is easy to intersect, which violates the idea of tangency, and the edge contact is serious, which is not conducive to transmission. In another case, the maximum load per unit tooth width is reduced to the minimum when the inclination is not inclined or the inclination angle is small, and the load distribution per unit tooth width is more reasonable.
Compared with ordinary helical gears, the drum tooth eliminates the edge contact, which reduces the maximum stress of the edge, but the load on the tooth surface is concentrated. Therefore, the above two cases should be met when designing the drum tooth.