There are 3 basic types of automatic transmissions found throughout the world. The Dual Clutch Transmission (or DCT), the Continuously Variable Transmission (or CVT) and the step-type transmission which is the most common. There are several main components that make up the step-type transmission. The pump supplies pressurized transmission fluid for many uses throughout the unit. The planetary gear sets provide the chosen gear ratios for the vehicle. Clutches or “clutch packs” engage and disengage the gear sets. The Torque Converter connects the transmission to the engine and multiplies the torque during initial acceleration. It uses two turbines which spin independently, but which are fluid coupled allowing the engine to idle while the engine is stopped and produce smoother acceleration as it shifts through the gears. Finally, the Mechatronics is the “brain” of the transmission, a complex system of ports, valves and electronics that control all transmission functions.
The one component of the entire system that’s critical to all of these parts working properly together is the Automatic Transmission Fluid, or ATF. It acts as a hydraulic fluid, to engage clutch packs & shift the gears. It acts as a corrosion inhibitor and wear protection for the Planetary Gear sets. It has to flow easily from minus 40 degrees Fahrenheit to nearly 400, even in fine valve assemblies. The ATF precisely controls friction in the clutch packs and maintains it throughout the drain interval … which is perhaps the most important property of an ATF all while providing lubrication to hundreds of moving parts even under high temperatures and extreme pressure. So using the right ATF is critical to the performance and long life of your transmission.