Semi-Manual Clutch (SMC)
Semi-Manual Clutch (SMC), sometimes referred to as a twin-clutch or double-clutch transmission, is a type of semi-automatic or automated manual automotive transmission. SMC uses two separate clutches for odd and even gear sets and could be described as two separate manual transmissions contained within one housing working as one unit. SMC are usually operated in a fully automatic mode however many have the ability to allow the drive to manually shift gears through the transmissions electro-hydraulics.
There are two types of clutch used in dual-clutch transmissions, either wet multi-plate clutches which are bathed in oil or dry twin-plate clutches. The wet design is generally used for higher torque engines whereas the dry clutch design is generally suitable for smaller vehicles with lower torque output.