Direct Shift Gear Box
The Direct-Shift Gearbox is an electronically controlled dual clutch multiple-shaft manual gearbox without the traditional clutch pedal, in a transaxle design, thus offering a full automatic transmission or semi-manual transmission control from the same gear box. Simply speaking its two separate manual gearboxes (and clutches) in one housing working as one unit. The two independent clutches in the DSG facilitates faster shift times by eliminating the torque converter of a conventional epicyclic transmission.
Floor mounted transmission (like the regular automatic transmission) lever shift controls of the DSG operates in a straight 'fore and aft' plane (without any dog leg offset movements). In-advertent selection of a wrong gear is prevented through an additional button on the transmission lever.
In the automatic mode it has following lever positions
P = Park
N = Neutral
D = Drive
S = Sport
R = Reverse
The floor shift lever also has another plane of operation, for manual mode, with spring-loaded "+" and "-" positions. Change over to the manual mode also changes the instrument display to 6 5 4 3 2 1
Better fuel economy of almost up to 15% more than conventional planetary geared automatic transmission (due to lower parasitic losses from oil churning).
No loss of torque transmission from the engine to the driving wheels during gear shifts.
Extremely fast up- shift time - just about only 8 milliseconds.
Slightly lower mechanical efficiency vs conventional transmission particularly on wet clutch variants. The need to trigger kick-down switch to achieve maximum possible acceleration or hill climbing at speeds higher than a certain limit (e.g. 3000 or 4000 RPM) is difficult.
Expensive to maintain as it requires specialist transmission fluids/lubricants with dedicated additives at regular intervals.
Makes new cars slightly expensive as the assembly is expensive.
Relatively lengthy shift time when shifting to a gear ratio, which the transmission ECU did not anticipate (around 1100 ms, depending on the situation).
Heavier as compared to a conventional manual transmission.