Landing gear creates a huge amount of drag, which is why airliners retract them into the fuselage. However, having the gear ...

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 ...

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 ...