A Worm-Planetary Gearbox is a type of gearbox with input stage as worm gear. The output of worm gear stage is internally connected to planetary gear stage.

The typical advantages of these type of Gear Boxes are that in worm gear we can have a high reduction ratio in a compact design, while the planetary gears can handle higher output torques. They are very smooth and very low noise Gear Boxes.

Another special advantage of this type of gear box is that it can offer high resistance to motion from output to input. This resistance depends on the ratio of worm gear box. Thus, these can be used where irreversibility is necessary (from load side to Input), typically for hoisting, inclined conveyors or similar applications, where it is necessary that the gear box does not rotate backwards in case of power failure. Such feature can be achieved only using higher ratio worm gear box.

One disadvantage of this type of gear box is that the efficiency of this gear box is low compared to the other types of Gear Boxes.

Worm Planetary Gearboxes are commonly used in applications that require high reduction ratios and low speeds, such as in Conveyors, Material Handling Systems, Inclined Conveyors, Hoisting, Material Processing Equipment etc.