From October 2018 the new A-Class is available with the permanent all-wheel drive system 4MATIC with fully variable torque distribution. This sporty all-wheel drive system has been developed further, and now offers even more driving pleasure and efficiency. Using the DYNAMIC SELECT switch, the driver is able to influence the 4MATIC characteristics even more than before.
4MATIC components include the power take-off to the rear axle, which is integrated into the automated dual clutch transmission, and the rear axle differential with an integrated multiplate clutch. This is no longer electro-hydraulically powered, but instead electro-mechanically.
Via a crown wheel and a ball ramp, an electric motor exerts an axial force on the clutch pack to open or close the plates. The rear axle differential compensates the different paths/rotational speeds of the rear wheels. The advantages of this control system are above all non-rpm-dependent operation across the entire actuation range, pilot control of the clutch while still stationary and higher efficiency thanks to the ball ramp concept.
Drive torque distribution between the front and rear axles is fully variable. Depending on the driving situation, 100% of the drive torque can be directed to the front axle (e.g. when driving straight ahead with no increased slip at the front axle), or in borderline cases up to 50% can be directed to the rear axle if the friction coefficient suddenly changes.
Using the DYNAMIC SELECT switch, the driver is able to influence the characteristics of 4MATIC even more than before. In the A-Class there are two characteristic curves available for clutch control. Models equipped with 4MATIC have a four-link rear suspension.