It has many advantages such as several couples of teeth meshsing simultaneously , double touching lines on each interacting surface , high transmission ratio and heavy load , etc . and it ' s easy to form elastohydrodynamics lubricant film between two interacting surfaces . but this kind worm gear drive is not used widely in china . the reason is that its manufacturing method - dual generating method - is outdated 但是，由于目前加工该型蜗杆副的方法为对偶法，必须专门加工蜗杆和专用蜗轮滚刀，对于不同参数的蜗杆副蜗轮滚刀不能通用并且在加工中需多次对刀，导致平面二包蜗杆副加工成本高而精度低。
