Worm and Worm Wheel: The gearbox consists of a worm (a type of screw) and a worm wheel (a gear in the form of a helical gear). The worm is driven by the input shaft, while the worm wheel is driven by the worm and is usually perpendicular to the worm.
Gear Reduction: Worm gearboxes provide a significant gear reduction ratio in a compact size. The reduction ratio is determined by the number of teeth on the worm wheel and the pitch diameter of the worm.
Self-locking: One of the distinctive features of worm gearboxes is their self-locking ability. This means the gearbox cannot be backdriven easily, which provides mechanical advantage in applications where holding torque is required.
Efficiency: Worm gearboxes typically have lower efficiency compared to other types of gearboxes (usually around 50-90%), due to the sliding action between the teeth of the worm and worm wheel. Efficiency can vary based on the design and lubrication.
Applications: They are commonly used in applications where space is limited but high gear reduction is necessary, such as conveyor systems, packaging machinery, elevators, and automotive applications (e.g., steering systems).
Design Considerations: When selecting a worm gearbox, factors such as torque requirements, speed reduction ratio, efficiency, backlash (play between gears), and lubrication requirements need to be considered.
Advantages: Compact size, high reduction ratio capability, self-locking feature, and quiet operation are some advantages of worm gearboxes.
