Twin-clutch transmission

A dual-clutch transmission, (DCT) (sometimes referred to as a twin-clutch transmission or double-clutch transmission), is a type of automatic transmission or automated automotive transmission. It uses two separate clutches for odd and even gear sets. It can fundamentally be described as two separate manual transmissions with their respective clutches contained within one housing, and working as one unit. Although usually operated in a fully automatic mode, many also have the ability to allow the driver to manually shift gears in semi-automatic mode, albeit still using the transmission's electrohydraulics.

This type of transmission was invented by Frenchman Adolphe Kégresse just before World War II, although he never developed a working model. The first development of the twin-clutch or dual-clutch transmission started in the early part of 1980 under the guidance of Harry Webster at Automotive Products (AP), Leamington Spa, with prototypes built into the Ford Fiesta Mk1, Ford Ranger, and Peugeot 205. Initially, the control systems were based on purely analogue/discrete digital circuitry with patents filed in July 1981. All of these early AP twin-clutch installations featured a single dry clutch and multiplate wet clutch. Following discussions with VW/Porsche, DCT work continued from Porsche in-house development, for Audi and Porsche racing cars later in the 1980s, when computers to control the transmission became compact enough: the Porsche Doppelkupplungsgetriebe (English: dual-clutch gearbox) (PDK) used in the Porsche 956 and 962Le Mans race cars from 1983, and the Audi Sport Quattro S1.

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