How Does a Gearbox Work?

A gearbox is a method of transmitting energy from one mechanical device to another. It works by increasing the torque while at the same time reducing the speed. Torque generates power by twisting and bending solid material. The gearbox is located in the power shaft, and every gear in the gearbox has a specific purpose in the operation of the vehicle. Each level of speed has a relative gear that gives your vehicle the right amount of speed and torque. A gear ratio is used to determine the level of force in each gear, and once this ratio is set, it cannot be changed.


A manual gearbox works when the clutch is pressed down. This allows the gearshift to be put into any desired gear. Most manual transmissions have five or six gears in their gear box.

When the gears in the gearbox are shifted into a higher gear, the gearbox gives the vehicle more power while using less fuel. This works because the gearbox rotates the driveshaft, alternating the torque and power.

When the gears are shifted into a lower gear, your vehicle will run at a lower speed. Gears engage the driveshaft at different points along the way. When the gear is lower, it will engage the driveshaft closer to the gearbox.


An automatic transmission's gearbox works in concert with the accelerator, brakes and driveshaft. The transmission in an automatic vehicle is more expensive and can be more difficult to maintain and replace. Automatic transmissions use the programmed gear ratio, and spin the driveshaft according to how much power is coming from the accelerator. When the brake in the vehicle is applied, the gearbox decreases the speed by using counterweights to slow the driveshaft.

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About the Author

Ted Marten lives in New York City and began writing professionally in 2007, with articles appearing on various websites. Marten has a bachelor's degree in English and has also received a certificate in filmmaking from the Digital Film Academy.