Drivetrain

In automotive engineering, the drivetrain is the components of a motor vehicle that deliver power to the drive wheels.

Other machinery, equipment and vehicles may also use a drivetrain to deliver power from the engine(s) to the driven components.

As the vehicle speed changes, the ideal engine speed must remain approximately constant for efficient operation and so this gearbox ratio must also be changed, either manually, automatically or by an automatic continuous variation.

[3] The powertrain consists of the prime mover (e.g. an internal combustion engine and/or one or more traction motors) and the drivetrain - all of the components that convert the prime mover's power into movement of the vehicle (e.g. the transmission, driveshafts, differential and axles);[4][5] whereas the drivetrain does not include the power source and consists of the transmission, driveshafts, differential and axles.

[6][7] Most passenger cars and commercial vehicles are powered by either an internal combustion engine, electric motor(s) or a combination of the two.