page_title: Dual-clutch transmission
section_title: Design
hierarchical_section_title: Dual-clutch transmission / Design
caption_attribution_description: Sectional view of the Volkswagen Group dual clutch Direct-Shift Gearbox (DSG) transmission
context_page_description: A dual-clutch transmission is a type of transmission that uses two separate clutches for odd and even gear sets. The design is often similar to two separate manual transmissions with their respective clutches contained within one housing, and working as one unit. In car and truck applications, the DCT functions as an automatic transmission, requiring no driver input to change gears.
  The first DCT to reach production was the Easidrive automatic transmission introduced on the 1961 Hillman Minx mid-size car. This was followed by various eastern European tractors through the 1970s, then the Porsche 962 C racing car in 1985. The first DCT of the modern era was used in the 2003 Volkswagen Golf R32. Since the late 2000s, DCTs have become increasingly widespread, and have supplanted hydraulic automatic transmissions in various models of cars.
context_section_description: The fundamental principle of a DCT is that one clutch drives a gear-set for the even-numbered gears, while the other clutch drives the odd-numbered gears. Since the DCT can pre-select an odd gear while the vehicle is being propelled in an even gear (or vice-versa), DCTs can achieve shift times faster than are possible using a manual transmission. By timing the operation of one clutch to engage at the precise moment that the other is disengaging, a DCT can shift gears without interrupting the torque supply to the wheels.
  A DCT uses clutch packs (as per a manual transmission), rather than the torque converter used by traditional (hydraulic) automatic transmissions. The DCT clutches are either "wet" or "dry" and are similar to the clutches used in most motorcycles. Wet clutches are bathed in oil to provide cooling for the clutch surface, therefore wet clutches are often used in applications with higher torque loads, such as the 1,250 N⋅m (922 lbf⋅ft) engine in the Bugatti Veyron.
  Several arrangements for the two clutches are possible, and are outlined below:
  Most automotive DCTs use two concentric clutch packs located on the same axis as the flywheel. Therefore the outer clutch pack has a larger diameter than the inner clutch pack.
  Many DCTs for tractors (such as the Fortschritt ZT 320) use a similar arrangement where the clutches are located on the same axis of the flywheel. The difference is that the clutches are at different positions on this axis (i.e. one in front of the other) and the same size as each other. This design is used by the Tremec TR-9070 DCT used by the 2020 Ford Mustang Shelby GT500.
  Another alternate design (as used by the Volkswagen DQ200 transmission) arranges two identical-size clutches located side-by-side. This design requires two side-by-side input shafts, which are driven from the crankshaft via gears.
caption: DCT based on a concentric clutch layout (inside the round black cover, shown in the center of the image)
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