S tronic means automatic

This is how a dual clutch transmission works

DSG, PDK or DCT: Depending on the car manufacturer, dual clutch transmissions have very different names. They can be operated as comfortably as an automatic, but usually work more efficiently than a manual transmission.

  • Fast gear changes without interruption of tractive effort

  • Fuel savings possible through high efficiency

  • Often more expensive than a variant with a manual gearbox

The dual clutch transmission combines the advantages of manual gearshifts with automatic belts and combines them into a new category. But does this technology really only offer advantages? Not quite. A transmission with double clutch - commonly known as DSG - also has some disadvantages.

What does DSG stand for?

Correct and official is the name of the component for automatically changing gears Double clutch, abbreviated DKG. The name in use today DSG means Direct shift transmission, but belongs to as a product name VWwho first introduced this technique on a large scale. Other brands of the Volkswagen Group call the automated manual transmission differently: Bei Porsche is it [called PDK, at Audi S tronic. A list of the most common names of the dual clutch transmission can be found in the infographic, sorted alphabetically by car manufacturer.

How does a dual clutch transmission work?

A dual clutch transmission works in the same way for all manufacturers: It consists of two partial transmissions and two clutches, hence the name dual clutch transmission. From a technical point of view, it is a direct shift transmission, so not an automatic transmission, but rather aautomatic transmission.

The basic principle: With a 6- or 7-speed DSG in a gearbox, the DSG is divided into two areas. A sub-area switches the odd gears 1, 3, 5 and 7, the other area changes the straight gears 2, 4, and 6. The advantage of a dual clutch transmission is that the next possible gear shift is permanently engaged while driving. This is how the Gear change without interruption of tractive effort very fast. The sub-transmissions work on a common transmission output.

Shift faster thanks to mechatronics

An example: If the car drives through town in fourth gear, the clutch of the shaft with the even gears remains closed and transfers the power. On the wave with the odd gears the fifth gear is already on, but the clutch remains open so that fifth gear runs idle, i.e. without power transmission.

If the driver accelerates, opens in hundredths of a second the coupling the fourth gear, that of the fifth gear closes and thus transmits the power of the engine to the drive wheels. At the same time, the dual clutch transmission puts the next gear back, in this case the sixth gear. Central element is the so-called Mechatronics, a combination of control electronics, oil pressure pump and actuating mechanism.

There are differences in the size of the gearboxes. Weaker engines with less torque up to 250 Newton meters put on dry clutches. They are smaller and lighter than Multi-disc multi-plate clutchesthat in one Oil bath to run. Manufacturers use this type of coupling larger drives with more torque over around 250 Newton meters. The disadvantage of a dual clutch transmission with an oil bath clutch: It loses part of its efficiency and is less efficient than a DSG with a dry clutch.

What are the advantages of dual clutch transmissions?

The dual clutch transmission - regardless of whether from Audi, Ford, Opel or VW - combines several advantages: Modern DSG weigh little, have compact dimensions and drive yourself economical, comfortable and sporty. Compared to conventional automatic transmissions with a hydraulic converter, DSG transmissions Save up to ten percent fuel. And even compared to the manual gearbox, the DSG can save fuel, depending on the driving style.

Added to this are those due to the non-existent interruption of tractive power very quick gear changes. Even professional racing drivers cannot do this faster with manual gearshifts than with a dual clutch transmission - a decisive reason why in many modern sports car more frequently Dual clutch transmission installed become. Additional ones then ensure a more driving experience and manual gear changes Shift paddles behind the steering wheel or the gearshift lever in the center console.

What are the disadvantages of a DSG?

Depending on the brand, model and engine combination, a DSG costs more than a manual gearbox between 1000 and 2500 euros surcharge. However, some manufacturers only offer certain engines with DSG. There are also disadvantages when it comes to driving comfort: depending on the manufacturer and type of double clutch transmission, the DSG is required a moment to remember after engaging the gear, until the propulsion begins - and often jerkily, because the two clutches close or open abruptly when starting off. This is particularly annoying when parking and in stop-and-go traffic.

This side effect usually occurs with dual clutch transmissions with a dry clutch, i.e. with smaller engines. Experienced drivers drive along a manual transmission therefore gentler at. Heavy sedans or SUVs with powerful engines usually continue to rely on automatic transmissions with torque converters. The conventional machines are heavier than a DSG, but they can transmit more torque and start off more smoothly.

Which problems can arise with the DSG?

Mechanics and electronics in cars wear out over time, this applies to manual transmissions as well as to automatic transmissions and dual clutch transmissions. In the past few years, the VW DSG in particular caused problems, or more precisely that 7-gear-DSG DQ200 with dry clutch. With this gear mostly the so-called Mechatronic broken, but sensors or couplings were also susceptible.

The exchange of the complete Component costs more than 2000 euros. In addition to cars from Volkswagen, those of the other group brands Audi, Seat and Škoda are also affected. In the USA, Volkswagen had to recall 13,500 vehicles with DSG to the workshops, in China it was around 384,000 vehicles in 2013, in Japan around 91,000 cars and in Germany in 2013 Volkswagen recalled around 257,000 vehicles.

Who invented the dual clutch transmission?

The first patents for a type of dual clutch transmission were registered in 1939 by the French inventor Adolphe Kégresse and a year later the Darmstadt professor Rudolf Franke at. But even a Morgan three-wheeler drove with a 2-speed dual clutch transmission until 1931 - the invention did not reach series production, however. in the Motorsport the technology was successfully used in the 1980s. Porsche built it under the name from 1984 Porsche double clutch transmission (PDK) for the first time in a type 962 racing car. With 54 victories and numerous championships, the vehicle is one of the most successful racing cars ever, especially in the endurance world championship.

Also in rally-Vehicles like the Audi Sport quattro S1 E2, a dual clutch transmission was introduced in 1985. World rally champion Walter Röhrl catapulted his work device from 0 to 100 km / h in 2.9 seconds, and after ten seconds it was 200 km / h. Thanks to PDK, Röhrl often won superiorly. The advantage also in rally sport: the acceleration takes place even more extreme without interruption of tractive power, every gear change is like an explosion. disadvantage: The technology demands in series vehicles immense computing capacityin order to meet the high demand for comfort in everyday use.

That wasn't possible then. It only started in 2002 Volkswagen the transmission in series vehicles, initially in Golf RS32, now under the brand name DSG. The Audi TT followed a little later. At Porsche, the conventional Tiptronic S automatic transmission was replaced by the PDK in 2008.

Text: Fabian Hoberg

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