worm wheel

English Thesaurus

1. gear with the thread of a worm (noun.artifact)

hypernym	:	cogwheel, gear, gear wheel, geared wheel,
definition	:	a toothed wheel that engages another toothed mechanism in order to change the speed or direction of transmitted motion (noun.artifact)

part meronym	:	worm gear,
definition	:	gear consisting of a shaft with screw thread (the worm) that meshes with a toothed wheel (the worm wheel); changes the direction of the axis of rotary motion (noun.artifact)