Such an automatic transmission is called a classic, as it appeared before the others, and is the most common to the present day. Its principle of operation is simple and complicated at the same time. It consists of two separate components – transmission and converter, that is, the last one is not part of the gearbox, and performs, in fact, the role of the clutch.
Torque converter consists of two vane machine – the centrifugal pump and a centripetal turbine. Between them there is a guiding device – reactor. The impeller is rigidly connected with the crankshaft of the engine, turbine – with a transmission shaft. The reactor, depending on the operating mode, may rotate freely and may be locked by means of an overrunning clutch.
Gearbox itself is very similar to the usual “mechanics”, with the exception of some fundamentally important details to ensure gear changes with virtually no interruption in tractive power and without a driver. A very important point is the fact that there is no the rigid link between the engine and gearbox. Gearbox torque is transmitted via the transmission oil, circulating under pressure in a closed circle.