- When a car is out of gear it cannot run .
- Put the gear lever in the neutral position .
- When the car is in gear it will move .
- Do not make the engine run fast when not in gear .
- The car started with a crashing of gears .
- a toothed wheel that engages another toothed mechanism in order to change the speed or direction of transmitted motion
同義詞：gear wheel, geared wheel, cogwheel
- equipment consisting of miscellaneous articles needed for a particular operation or sport etc.
- a mechanism for transmitting motion for some specific purpose (as the steering gear of a vehicle)
- wheelwork consisting of a connected set of rotating gears by which force is transmitted or motion or torque is changed; "the fool got his tie caught in the geartrain"
同義詞：gearing, geartrain, power train, train
- set the level or character of; "She pitched her speech to the teenagers in the audience"
A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine.