![]() CVTs also reduce shift shock and increase fuel efficiency significantly. A CVT is a type of automatic transmission that uses a moving pulley system and a belt or chain to infinitely adjust the gear ratio across a wide range. One of the most notable is the continuously variable transmission, or CVT. In addition, manufacturers are already investing heavily in alternate transmission technologies. This could initially drive up the costs of cars outfitted with DCTs, which might discourage cost-conscious consumers. However, some automakers are wary of the additional costs associated with modifying production lines to accommodate a new type of transmission. Many car manufacturers are interested in DCT technology. Some experts say that a six-speed DCT can deliver up to a 10 percent increase in relative fuel efficiency when compared to a conventional five-speed automatic. Because power flow from the engine to the transmission is not interrupted, fuel efficiency increases dramatically. Perhaps the most compelling advantage of a DCT is improved fuel economy. Best of all, it affords drivers the luxury of choosing whether they prefer to control the shifting or let the computer do all of the work. It certainly offers smooth acceleration by eliminating the shift shock that accompanies gearshifts in manual transmissions and even some automatics. With upshifts taking a mere 8 milliseconds, many feel that the DCT offers the most dynamic acceleration of any vehicle on the market. Even without a clutch pedal, the driver can still "tell" the computer when to take action through paddles, buttons or a gearshift.ĭriver experience, then, is just one of the many advantages of a DCT. What it doesn't have is a clutch pedal, because computers, solenoids and hydraulics do the actual shifting. In principle, the DCT behaves just like a standard manual transmission: It's got input and auxiliary shafts to house gears, synchronizers and a clutch. ![]() Hopefully it's becoming clear why the DCT is classified as an automated manual transmission. Using this arrangement, gears can be changed without interrupting the power flow from the engine to the transmission. One clutch controls the odd gears (first, third, fifth and reverse), while the other controls the even gears (second, fourth and sixth). In a DCT, however, the clutches operate independently. Sophisticated electronics and hydraulics control the clutches, just as they do in a standard automatic transmission. Instead, power delivery changes from on to off to on during gearshift, causing a phenomenon known as "shift shock" or "torque interrupt." For an unskilled driver, this can result in passengers being thrown forward and back again as gears are changed.Ī dual-clutch gearbox, by contrast, uses two clutches, but has no clutch pedal. So, in a conventional manual transmission, there is not a continuous flow of power from the engine to the wheels. Once the new gear is engaged, the driver releases the clutch pedal, which re-connects the engine to the gearbox and transmits power to the wheels. Devices called synchronizers match the gears before they are engaged to prevent grinding. Then the driver uses the stick shift to select a new gear, a process that involves moving a toothed collar from one gear wheel to another gear wheel of a different size. This operates a single clutch, which disconnects the engine from the gearbox and interrupts power flow to the transmission. ![]() When a driver wants to change from one gear to another in a standard stick-shift car, he first presses down the clutch pedal. To understand what this means, it's helpful to review how a conventional manual gearbox works. Hands-On or Hands-OffĪ dual-clutch transmission offers the function of two manual gearboxes in one. This article will explore how a dual-clutch transmission works, how it compares to other types of transmissions and why some predict that it is the transmission of the future.
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