Technology Spotlight: Audi Direct Shift Gearbox and Continuously Variable Transmissions

Most technological developments in the automotive industry never make it off the drawing board. The few that possess enough ingenuity or outright convenience to get further are generally subjected to significant periods of testing and refinement before ever being seen as a prototype. Many of these, in fact, also end up in the scrap heap. Technological developments in computers, however, have drastically reduced the time and expense required to produce a major automotive component.

One such development whose time has come is what Audi calls the DSG or Direct Shift Gearbox. This manual/automatic hybrid of a transmission is a progression of the Tiptronic-type transmission developed by the Germans years ago and that have become an industry standard across most brands.

While considerably different in design, the way in which the system operates is similar to many of the racing-inspired transmissions seen today which feature paddle or button shift controls located either on or directly behind the steering wheel. Basic shifting improvements have been made that produce lightning fast gear changes requiring a mere 0.02 seconds to complete. The interruption in power delivery characteristic of a conventional automatic is notably absent as well.

By employing a second shaft -- one for even-numbered gears and one for odd -- and sophisticated software, the transmission pre-selects the driver's anticipated next gear. This makes the transition more seamless than a soap bubble, a snug-fitting wonder bra, a Fred and Ginger dance routine, a wetsuit or silk stocking (you get the gist).

Other manufacturers have certainly taken note of the DSG design. Porsche is said to be among the several that will be employing such a system in their upcoming models.

It should also be noted that Audi has a second transmission already available on many of its models called CVT or Continuously Variable Transmission, which utilizes a vanadium-hardened steel chain to transfer torque between engine pulleys. Driving a CVT-equipped car feels more like driving a single speed golf cart than a car in its delivery of power. Gone is the lurching and delay of traditional automatics. Audi also programmed six gear-simulated drive ratios for those who find the smoothness unnerving.

Neither of these transmissions is entirely groundbreaking. In fact, variants of the CVT have been around since the 1800's. And although they may be more evolutionary than revolutionary, it's technology that has allowed both to go mainstream. Like a contemporary singer putting her spin on a timeless classic, Audi has reached into the dustbin and found more than one treasure.

What quirky automotive features abandoned "way back when" would you like to see re-developed in future models? Email me at grantsautorants@hotmail.com with your thoughts.

For a good description of the DSG, please see:
http://mydreams.go.ro/art_direct_shift.html

For a good description of the CVT, please see:
http://www.edmunds.com/ownership/techcenter/articles/45104/article.html

Comments

[Ken Bennett]

Years ago at the Slumph Museum I saw an old prototype using a ball and disc CVT. Do you know anything of its history?

Ken Bennett