What is an overdrive automatic transmission?
Automatic overdrive transmissions (AODTs) are the single most common drivetrain used in American automobiles. Modern AODTs offer levels of convenience, comfort and fuel economy undreamed of when they were first used decades ago.Overdrive DefinitionAn overdrive transmission utilizes a relatively simple power-rerouting system to enable the transmission’s output shaft to spin faster than its input shaft.FunctionAn overdrive gear is exactly the opposite of the standard gearing used in the first one or two gears, which give the engine more mechanical advantage. Bicycles often use overdrive, where the pedal (crankset) gear is larger than the wheel gear.BenefitsOverdrive transmissions allow an engine to run at a lower RPM during cruise than it otherwise would, saving gas and helping the engine to last longer.Lock-Up ConvertersAlmost all modern AODTs use lock-up torque converters that positively lock the engine to the transmission’s input shaft.
