A worm gear is a type of gear consisting of a screw-like worm and a toothed wheel called a worm wheel or worm gear wheel. The worm has a helical thread that meshes with the teeth of the worm wheel, and as the worm rotates, it drives the worm wheel.
Worm gears are commonly used to transmit motion and power between non-intersecting, perpendicular shafts. They offer several advantages over other types of gears, including their ability to provide high reduction ratios with a single stage, high efficiency, and self-locking characteristics.
One of the key features of worm gears is their ability to provide a high reduction ratio in a compact package. The reduction ratio is determined by the number of teeth on the worm gear wheel and the pitch of the worm thread. This makes them particularly useful in applications where space is limited, such as in industrial machinery, automotive transmissions, and power tools.
Worm gears are also known for their high efficiency, with efficiency levels of up to 90% being possible. However, they can generate a significant amount of heat due to friction, which can be a concern in high-speed applications.
One of the unique characteristics of worm gears is their self-locking capability. Because of the angle of the worm thread, the worm gear cannot back drive the worm. This means that the gear ratio can act as a brake, preventing the system from being driven in reverse. This makes them useful in applications where it is important to maintain a fixed position, such as in hoists and lifts.
Overall, worm gears are a versatile and useful type of gear that offers several advantages over other gear types.