What is a Dual-Clutch Transmission?
A dual-clutch transmission is an automatic transmission system for cars that uses two clutches instead of one. It is also known by one of the following terms:
' Twin clutch;
' Semi-automatic clutch; or
' Automated manual transmission.
How does it work?
In a dual-clutch transmission, the gears are separated into two sets: even-numbered gears and odd-numbered gears. A larger (outer) clutch controls the odd-numbered gears while a smaller (inner) clutch operates the even-numbered gears. In a normal (single-clutch) transmission, each time the clutch pedal is depressed, the engine is disengaged while the driver selects the desired gear. While the engine is disengaged, the torque distribution to the driveshaft is interrupted (watch how your revs drop when you push your clutch in). This effect is also referred to as 'lag'.
Then, once the gear has been selected and the driver releases the clutch, the engine is once again engaged and power flows back into the driveshaft. During this process the car slows down just a little, and the fuel supply into the engine ebbs and flows according to whether or not the clutch is engaged. With a dual-clutch transmission, gear-changes are performed automatically (there is no clutch pedal for the driver to operate), and the torque is transferred to the other clutch during gear changing. This ensures that 100% of the engine's power is transferred to the driveshaft at all times.
What are the benefits of a dual-clutch transmission?
Apart from a smoother ride, drivers of vehicles equipped with dual-clutch transmission will experience the following benefits:
' Reduced lag;
' Better control;
' Improved torque;
' Improved fuel efficiency (up to 10% less fuel is consumed);
' Quicker gear shifts (around 8 milliseconds per shift);
' Smoother, more dynamic acceleration; and
' The choice between manual and fully automatic gear-shifting.
What are the disadvantages of dual-clutch transmission?
For one, manufacturers have to completely redesign their cars to accommodate the different transmission, which drives car prices up. In short, it costs more to produce, which means the consumer ultimately pays more at the showroom. Also, even though dual-clutch transmissions are only just becoming known in the general driver arena, they may soon be obsolete as car manufacturers focus on even more advanced technologies. Another disadvantage for some drivers is the loss of interaction with the car while driving. Many drivers prefer the sheer pleasure of manually shifting gears to having the computer/engine do it automatically for them.
Who invented the dual-clutch transmission?
First invented in the late 1930s by French national Adolphe K'gresse, the dual-clutch transmission was later used in development by Porsche, most notably in Porsche and Audi race cars in the late 1980s. In 2003 the Volkswagen Golf Mk4 R32 was the first series production car to be released onto the market fitted with a dual-clutch transmission. Nowadays, most luxury vehicles, including those manufactured by BMW, Mercedes-Benz, Porsche and many others, sport seven-speed dual-clutch transmissions as standard.
What could possibly be better than a dual-clutch transmission?
Meet the continuously variable transmission, or CVT. Still a relatively brand-new technology, the CVT uses an entirely different system (one that uses a moving pulley and chains or belts) to adjust gear ratios across a range. Because it uses a continuous 'loop' and not a set number of gears, the potential for the number of gear ratios it can employ are almost infinite. But car manufacturers who have spent billions on upgrading their vehicle lines needn't worry just yet. CVT technology is not expected to dominate the market anytime soon. With DCT engines predicted by those in the know to capture around 25% of the world market this year, vehicles fitted with CVTs will barely make a 1% dent in global vehicle sales.
Which car manufacturers currently produce cars with dual-clutch transmissions? Here is a list of all manufacturers that use dual-clutch technology in their cars. When shopping for a new car, ask your dealer for a list of models and prices.
Should You Buy a Car With a Dual-Clutch Transmission? Go to www.autoguide.com to know.
Should You Buy a Car with a CVT Transmission? Go to www.autoguide.com to know.
Edited by: Rajesh Bihani ( Find me on Google+ )