I bought a Volkswagen with an automatic. A fellow worker, the car nut in the office, congratulated me for getting a DSG. What the heck is a DSG?
DSG stands for Dual Shaft or Direct Shift Gearbox, a relatively new approach to shifting gears without a clutch. You can think of it as an automated manual transmission.
First developed by Porsche in the 1980s for racing applications, it is lighter, smaller and more efficient than a conventional automatic - attributes that make is especially attractive in this day and age of tighter fuel economy and emission regulations.
A DSG transmission contains a pair of shafts and two clutches. For the purposes of this explanation let's say this is a six-speed transmission. One shaft will have first, third and fifth gears and the other second, fourth and sixth. The engine spins both shafts and when you start off, the clutch on the first shaft engages and you get under way in first gear.
While this is happening, the other shaft is pre-positioned to engage second gear. When an electronic message tells the transmission to shift, the clutch on the first shaft is released and that on the second shaft engaged. Now you are accelerating in second gear while the first shaft is getting third gear in position and so. These shifts happen in hundredths of a second.
In a "conventional" automatic transmission a fluid coupling called a torque converter - a big, heavy, round device and lots of fluid - is used to transmit the spinning motion of the engine to the transmission. Some early attempts at automated manuals were pretty rudimentary with clunky shifts and lots of other issues. But sophisticated electronics have made it the transmission of the future.
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