Worm Gears
A worm drive is a gear arrangement in which a worm (which is a gear in the form of a screw) meshes with a worm gear (which is similar in appearance to a spur gear). Worm gears are used to transmit power between two non intersecting, non parallel shafts. The simplest way to obtain a large speed reduction with high torque in a compact space is with worm gear drives. The speed ratio can vary from 1/10 to 1/300.
Classification of worm gears
Single enveloping worm gear
Double enveloping worm gear
1. Single enveloping worm gear 2. Double enveloping worm gear
Self Locking of Worm gear drive
Self-locking is defined as the inability of worm wheels to drive the worms. Factors affecting the self-locking feature include
the materials of the worm and worm wheel, lead angle, precision of manufacture, types of bearings, lubricant, etc. But in general, self-locking will occur when the lead angle in a single thread worm is less than 4。.
Design of Worm Gears
