Direct-Shift Gearbox - Operational Introduction

Operational Introduction

The internal combustion engine drives two clutch packs. The outer clutch pack drives gears 1, 3, 5 (and 7 when fitted), and reverse — the outer clutch pack has a larger diameter compared to the inner clutch, and can therefore handle greater torque loadings. The inner clutch pack drives gears 2, 4, and 6. Instead of a standard large dry single-plate clutch, each clutch pack for the six-speed DSG is a collection of four small wet interleaved clutch plates (similar to a motorcycle wet multi-plate clutch). Due to space constraints, the two clutch assemblies are concentric, and the shafts within the gearbox are hollow and also concentric. Because the alternate clutch pack's gear-sets can be pre-selected (predictive shifts enabled via the 'unused' section of the gearbox), un-powered time while shifting is avoided because the transmission of torque is simply switched from one clutch-pack to the other. This means that the DSG takes only about 8 milliseconds to upshift. In comparison, the sequential manual transmission (SMT) in the Ferrari F430 Scuderia takes 60 milliseconds to shift, or 150 milliseconds in the Ferrari Enzo. The quoted time for upshifts is the time the wheels are completely non-powered.

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