More manoeuvrable and dynamic thanks to steerable rear wheels

Thanks to rear-axle steering (optional), the S-Class feels as manoeuvrable as a compact car in the city. The steering angle at the rear axle is up to ten degrees. The turning circle is reduced by up to two metres.

The interaction between the front-axle and rear-axle steering is configured to ensure agile responsiveness in urban and country traffic together with a very high level of stability. This results in e.g. small side-slip angles and a high level of yaw suppression. At high speeds the focus is more on stability, though without compromising precision and responsiveness. This added value is achieved by integrated actuation of the steering and brakes (ESP®), and considerably improves handling safety as a result.

Customers have a choice of two variants of the optional rear-axle steering: 4.5° and 10° rear-axle steering. In the 10° variant the wheel size is limited to 255/40 R 20, allowing a larger wheel angle. These are the other differences:

 

Without rear-axle steering

With rear-axle steering

Max. steering angle at the rear axle (°)

0

4.5

10

Turning circle (m)
S-Class with short wheelbase (W 223)

Rear-wheel drive

12.2

11.4

10.5

4MATIC

12.5

11.6

10.7

Turning circle (m)
S-Class with long wheelbase (V 223)

Rear-wheel drive

12.5

11.7

10.8

4MATIC

12.8

11.9

10.9

S-Class models with rear-axle steering have an approx. 15 percent more direct steering ratio at the front axle. This means that the driver needs to turn the steering wheel by much less. The respective rear-axle angles and trajectories are shown in the driving mode menu in the central display.

The operating principle of rear-axle steering in detail: An electric motor drives a spindle at the rear axle via a drive belt. This makes axial adjustments to the spindle. Depending on the speed and the steering angle, the rear wheels are turned in the same or the opposite direction as the front wheels (same-direction or counter-direction steering). In simplified terms, this produces more agility and a smaller turning circle by counter-steering and more stability with same-direction steering. In the S-Class, the full steering angle of ten degrees is especially used during parking manoeuvres. The environmental data of the vehicle sensors (radar, camera, ultrasonic) are used to adapt the maximum angle to the relevant situation. The system switches from counter-direction to same-direction steering at more than 60 km/h.

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