The entire drive (both worm and wheel) can be classified as follows:

;Non-throated worm drives
: These don't have a throat, or groove, machined around the circumference of either the worm or worm wheel. ;Single-throated worm drives
: The worm wheel is throated. ;Double-throated worm drives
: Both gears are throated. This type of gearing can support the highest loading.

Types of worms

These classifications refer to the worm itself:

;Enveloping worm (hourglass worm)
: The worm has one or more

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