The multitronic® is a continuously variable transmission. It combines the dynamics and economy of a manual gearbox with the convenience of automatic transmission.
The smooth and powerful acceleration achieved with the multitronic is a major advantage over a conventional automatic gearbox and, because the engine is kept running close to its optimum operating point, fuel consumption is generally lower than with a manual gearbox.
A power-transmitting steel link-plate chain (tension chain) runs in an oil bath between two pairs of variable conical pulleys. These form the variator. The link-plate chain, consisting of over 1,000 link plates and 75 pairs of pins, can transmit torques of up to 330 newton metres. Pushing the faces of the two conical pulleys closer together or moving them further apart causes the link-plate chain to run further towards the inside or outside of the pairs of conical pulleys. This produces continuous adjustment of the gear ratio to achieve the optimum in every driving situation.
The adjustment of the conical surfaces takes place hydraulically and is based on various control characteristics. A hydraulic torque sensor ensures that the link-plate chain is always correctly tensioned and that the torque is transferred without slip.
The hydraulic multi-plate clutch achieves better ride comfort and agility thanks to its electronic control. It also helps to reduce fuel consumption.
If the driver applies the brakes when waiting at traffic lights, for example, the electronics reduce the tendency to creep forwards by decoupling the engine and the gearbox.
All the control parameters from the driver, engine and vehicle are registered by the electronic-hydraulic control unit in the gearbox housing. The dynamic gear control program (DCP) thus recognises from the position and movement of the accelerator whether the driver is adopting a sporty or a fuel-saving style of driving.
As with the tiptronic transmission, manual gear changes are possible, and up to eight simulated gears are available depending on the transmission version.