1. you can get great gear ratio, compact crossed helical gears.

2. the line contact between the two gear tooth surface, and its carrying capacity is much higher than of crossed helical gears.

3. the worm drive is equivalent to screw, multi-tooth meshing transmission, steady transmission, low noise is very small.

4. with locking. When the lead angle of the worm is smaller than the equivalent friction angle between the meshing teeth, body with locking, reverse lock can be realized, that is, only by a worm drive worm wheel, not driven by worm gear worm. Using self-locking worm gear in the crane, its reverse lock security protection.

5. low transmission efficiency, more serious wear. When the worm gear transmission, between the meshing teeth of sliding speed, the friction loss and low efficiency. The other hand, the relative sliding velocity ambassadors tooth wear, fever, severe, in order to heat dissipation and reduce wear, often using expensive friction and better abrasion resistance of materials and good lubrication device, thus higher costs.

6. the worm shaft and larger force.