What Is a Gearbox?

A gear is a simple device that can change the speed, direction or torque of a motor. Visually, a typical gear looks like a wheel with teeth around its circumference. A gearbox usually refers to a car's transmission, which is full of gears.

Gear

  • Gears are used in many machines and devices. Common examples of gears can be seen in the innards of a watch or a ten-speed bicycle. More complicated sets of gears will be found in automotive transmissions, or gearboxes.

Speed

  • If a gear driven by a motor (the input gear) has more teeth than the gear it is connected to, the connected gear, or output gear, will move faster than the input gear. This increases speed at the output. Reversing the gearing will reduce speed at the input.

Direction

  • Gears change direction as they mesh with other gears. When placing gears at different orientations, like horizontal gears meshing with vertical gears, the output direction could be drastically different than the input direction.

Torque

  • Basically, when gears reduce speed, they increase torque, or force that can be used to turn wheels or other gears.

Manual

  • A driver selects each gear in a manual car transmission. Selecting different gears allows the car to travel at different speeds and even in different directions.

    A manual transmission gives the driver more control over his vehicle.
    A manual transmission gives the driver more control over his vehicle.

Automatic

  • An automatic transmission selects the most appropriate gear for the driver. The driver only selects a few general gears like "drive" or "reverse."

    An automatic transmission works smoothly and efficiently.
    An automatic transmission works smoothly and efficiently.