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Core Characteristics of Worm Gears and Worms

May 15,2026

Large gear ratio
A single-stage gear ratio can range from 10:1 to 100:1, and even higher (e.g., up to 1500:1 in indexing mechanisms). For example, a single-start worm (with a lead of 1) paired with a 60-tooth worm wheel yields a gear ratio of 60:1—meaning that for every 60 revolutions of the worm, the worm wheel completes 1 revolution.

Compact structure
At the same transmission ratio, worm gear sets are significantly more compact than multi-stage gear reducers, making them ideal for space-constrained applications, such as vertically mounted equipment.

Self-locking
When the lead angle of the worm (the angle between the helical thread and the axis) is smaller than the friction angle of the tooth surface, the worm gear cannot be driven in the reverse direction. This characteristic is critical in lifting equipment such as elevators and winches, as it prevents the load from falling and enhances safety.

Smooth transmission and low noise
During meshing, contact is line contact (the worm gear teeth are arc-shaped and partially envelop the worm), resulting in a large contact area, uniform stress distribution, and low impact loads, making it suitable for precision equipment such as machine tool feed mechanisms.

Can change the direction of transmission
The worm is typically mounted horizontally, with the worm wheel positioned perpendicular to the worm shaft, thereby achieving a right-angle, intersecting drive between the input and output shafts.

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Application Fields of Spur Gears