(2) In other sections of the parallel main section, there are a pair of different non-involute rack and pinion meshes, but regardless of the shape of the meshing tooth profile, there is a meshing point (touch point). The collection of these profiles shows that the meshing of the worm and worm gear is a line touch, and the meshing of each pair of gear teeth is also gradually engaged and gradually withdrawn, so the touch line also changes from short → long → short.As a result, the worm and worm gear drive is stable, has low vibration and noise, and carries a high level of skill.
(3)在主剖面内有基本参数：模数和压力角。关于蜗杆称轴面模数ma1和轴面压力角aa1；关于蜗轮称端面模数mt2和端面压力角at2。
(4) 蜗杆蜗轮传动能够获得较大传动比。因为蜗杆的齿数z1较少，蜗轮的齿数z2能够许多，因而传动比i12=w1/w2=z2/z1能够很大，通常i12=10 ~ 100。在分度组织或手动组织中，i12可达300以上。
(5) Worm and worm gear drives are usually self-locking.When the spiral lead angle l of the worm is smaller than the equivalent friction angle between the gear teeth, the worm and worm gear tissue will be self-locking, that is, it cannot be transformed by the worm gear and the worm (see Chapter XNUMX for the self-locking property of the tissue).Because of this self-locking (self-locking), so that the worm and worm gear tissue is often used in lifting equipment.
