ABSTRACT
Gears are used to transmit power between shafts: they may be parallel, at an angle, or perpendicular to one another. Power transmission is necessary for multiple reasons, including providing torque multiplication at low speeds; reducing engine revolutions per minute (rpm) at highway speeds; allowing the engine to operate within its most efficient rpm range; and allowing the engine to be disengaged from the rear wheels while the vehicle is not moving (torque converter and clutch). There are three basic purposes of transmission: (1) to alter shaft rpm; (2) to multiply torque; and (3) to reverse the direction of shaft rotation.
