Worm refers to a gear with one or several spiral teeth, which mesh with the worm gear to form a cross shaft gear pair. Its graduation surface can be cylindrical, conical or toroidal, including Archimedes worm, involute worm, normal straight profile worm and cone wrapped cylindrical worm.
Worm gear mechanism is often used to transmit motion and power between two staggered shafts. The worm gear and worm are equivalent to gears and racks in their intermediate plane, and the worm is similar to the screw in shape.
