Probably the people who've pulled them apart and seen inside them.
The argument for the 7speed dry clutch was for energy efficiency re transmission power loss compared to 6speed oil clutch .
With 7Speed Golf clutch, had several occasions where DSG suddenly disengaged (due to over temperature? while slowly into position uphill)
However re the 6 speed DSG fitted to my Passat, this is so much better than older cars I have driven with conventional torque converters. Unless one watches the Tacho' one is not aware if any change has taken place. BUT and I mean BUT, re BlueMotion, this is a Bugger. Many times I pull up at a roundabout then I see my opportunity. What happens? The car stalls at the most critical moment!
MY13 Passat 130TDI Sedan. Autumn Brown Metalic, Desert Beige seats. Sat nav, Rev camera, Dynaudio, 12way adj seats. No ACC Previous Golf 118 TSI with ACC given to my son
The DSG is nothing like a preselector gearbox - a la Armstrong Siddeley, Daimler and some modern buses.
The preselector box has a series of epicyclic (planetary) gear trains just like a conventional auto box. A specific gear is selected electrically in advance (preselected) and engaged mechanically when needed by pressing a "clutch" pedal. The "clutch" pedal applies a brake band to the preselected planetary gear with a big spring. Preselector boxes often have a fluid flywheel (like a modern torque converter) or a centrifically engaged mechanical clutch. In modern applications, the mechanical engagement can be power actuated.
A DSG is two parallel conventional gear sets, with two co-axial clutches - operated, as Umai Naa says, by electrickery and hydraullickery.
It certainly is a conventional style box
It's just that the two shafts are not parallel, one is inside the other
Our hand and foot have been replaced by electrickery and hydraullickery
Don't get me wrong - the electrics managing the box are very smart
VW had to create a faster diverter valve to handle the fast gear changes
The clutches are interesting to see (for ages I could not work out how that part worked)
2012.1 Skoda Octavia VRS DSG Wagon - Carbonio cold air intake and pipe - HPA Motorsports BBK 355mm rotors 6 pot calipers
APR Stage II ECU - APR 3" exhaust down pipe & high flow catalyst
APR/HP Roll bars - Eibach springs and Bilstien shocks
Supaloy lower control arms - Enkei 18*8 Wheels
I still want to know how the rotating mass of crank, rods and pistons can be moved 500rpm in 6 milliseconds (a fifth of a blink of the eye) unless the tacho is fibbing of course.
Multiples of clutches have nothing to do with the basic physics of controlling the rotational mass.
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