The mating gear of a worm drive, with teeth curved along a concave throat so they envelop the worm and give line contact. Wheels are usually tin or phosphor bronze running against a hardened, ground steel worm, a pairing that resists seizure under heavy sliding. They are hobbed with a hob matched to the worm, and wear is expected: bronze debris in the oil is normal in moderation.
Worm wheel's lost half its tooth thickness, there's bronze glitter all over the drain plug, order a new set.
Also heard as
- worm gear
- wormwheel
Related terms
Worm
A screw-shaped gear with one or more threads that drives a worm wheel at right angles for a large reduction.
Hobbing
Generating gear teeth with a rotating worm-shaped cutter that turns in step with the blank.
Run-in
Operating new gears at reduced load at first so surface high spots wear smooth before full duty.