Mercedes-Benz has unveiled a new 4MATIC permanent all-wheel-drive system that will be used for its models with transversely mounted engines. The new 4MATIC will complement the four all-wheel drive versions that Mercedes-Benz already offers. The first models to get the new system will be the 2014 CLA-Class and CLA 45 AMG models.
The 4MATIC all-wheel drive is a completely new development tailored to the requirements of the new models with front-wheel drive. The most innovative components of the new 4MATIC include the power take-off to the rear axle which is integrated in the 7G-DCT automated dual clutch transmission and the rear-axle gear unit with integrated, electrohydraulically controlled multi-disc clutch. This set-up enables fully variable distribution of the drive torque between front and rear axle.
The new 4MATIC is being combined with the 7G-DCT seven-speed automated dual clutch transmission which was premiered in the B-Class. The power flux to the rear powertrain is provided by a compact power take-off unit (PTU) which is fully integrated in the main transmission and is supplied with lubricant from the latter's oil circuit. The weight of the new 4MATIC is up to 25 percent lighter than the all-wheel drive versions offered by the automaker's rivals.
The 4MATIC is activated according to the basic principle of "as often as necessary, as rarely as possible". This means that when the underlying conditions allow, the all-wheel drive CLA models run almost exclusively in particularly economical front-wheel drive mode. As soon as the driving situation requires, drive torque is channelled to the rear axle as appropriate.
The torque distribution ratio is also dependent on the activated shift program of the 7G-DCT dual clutch transmission. The ECO program channels less torque to the rear axle, resulting in gentler handling and supporting an economical driving style at lower revs. In SPORT or MANUAL mode the activation times are shortened and more torque is distributed to the rear axle in the interests of a dynamic, sporty driving style. On the AMG versions, adaptation of the 4MATIC controller takes place in accordance with the 3-stage ESP.
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