Previously believed to be only human-made, a natural example of a functioning gear mechanism has been discovered in a common insect -- showing that evolution developed interlocking cogs long before we ...

Backlash, a clearance between mating gear teeth, is built into speed reducers to let the gears mesh without binding and to provide space for a film of lubricating oil between the teeth. This prevents ...

An internal gear hub provides multiple gears on a bicycle in an enclosed unit housed within the rear hub. Almost all bikes with gears now feature a derailleur system. But for a long time, internal ...