continued from ESP

Sensotronic Brake Control (SBC)

More effective kicking

Sensotronic Brake Control is the name given to an innovative electronically controlled brake system which will be fit to future passenger vehicles of the Stuttgart manufacturer. It shall perfect the art of deceleration.

Stuttgart. When a driver presses the brake pedal, his foot moves a piston, which is connected to the brake booster and master cylinder.

This means: The firmer the push, the higher the pressure in the brake lines, and the higher the force exerted by the brake pads onto the brake disc. A simple principle. With Sensotronic Brake Control (SBC) there will still be a brake pedal and master cylinder, but there are quite a few differences as well.

Because the driver's brake commands are processed by a computer, which also continuously receives sensor signals from each individual wheel and the steering system. From these data the optimal brake pressure is calculated for each wheel individually. And this, promises Mercedes, is advantageous, when braking with full force, when braking in curves or on slippery surfaces.

The driver doesn't feel any of this. The push onto the brake pedal feels like it always did. But starting from the master cylinder it doesn't continue hydraulically, but electronically. Sensors obtain the pressure and the speed, with which it builds up. This information is passed electrically to the controller, which then calculates the brake force - as described above. If the electricity fails and SBC stops working, the good old hydraulic will be used instead, and the car decelerated via the front wheels.

SBC STOP

The system offers several additional functions besides a new braking behavior, due to its electronic brain: In stop-and-go traffic the vehicle brakes automatically, when the foot is lifted off the accelerator pedal ("Traffic Jam Assist"). It can be engaged under 10 MPH, using the the cruise control lever and switches off automatically at higher speeds. It remains active under 40 MPH. When engaged the instrument cluster indicates "SBC S". One can also activate it on downhill slopes via cruise control, so the car won't speed over the set limit. It was deleted starting with MY 2005.

SBC SOFT STOP

is not yet released, though few people are aware of it since Mercedes advertises it already. It might be released lateron. In city traffic soft-stop supposedly allows soft, jerkless stopping. Not sure if it's needed since SBC brakes can be modulated well, with good feel.

SBC HOLD

A "drive-away assistant" prevents the vehicle from rolling backwards or forward when starting on a hill or steep incline. A firm push onto the brake pedal, and the car remains stopped, even when taking the foot off the brake pedal, until the driver accelerates and the vehicle begins to roll. When set, the instrument cluster indicates SBC HOLD. I like using this function and miss it when switching back to other cars. As far as I know it was first introduced in the spring of 2003 in the 04 E-class Estate and lateron in the 2004 SLs.

DRY BRAKE

And finally there is the dry brake function. It is always activated when the windshield wipers run. The system then knows, that it rains and, with short brake pulses unnoticed by the driver, keeps the brake discs always dry and fully functional.

Braking in a curve. Left: conventional. Right: with SBC.
Notice the unequal braking forces, smaller lateral force, better stability and alignment with SBC.

SBC world premiered at the international auto show (IAA) in Frankfurt in September 2001 with the new SL, in a 2 wheel drive version. The new E-Class followed in 2002, and the Estate in 2003. The full four-wheel drive Sensotronic debuted in the E-Class 4matic in 2003.

Cars with SBC
Mercedes SL roadster (R230)
Mercedes E-Class sedan (W211) and Estate (S211) until mid 2006
Mercedes E-Class 4matic sedan (W211) and 4matic Estate (S211) until mid 2006
Mercedes SLR McLaren (C199)
Maybach 57 and 62 (W240)
Mercedes CLS coupe (C219) until mid 2006

Bosch SBC schematic
Mercedes SBC schematic
MB SBC in a curve

SBC to be adapted or changed
Due to its complexity, serviceability and costs, Sensotronic may be changed in future Mercedes models. Several of the new SBC functions may be integrated into a more conventional hydraulic ESP system.
September 15, 2003

SBC service and recall
Brake pads and fluid levels are inspected during normal servicing. With the new electric braking system additional items need to be checked. The codes need to be read out and if the brake system has been activated more than 300,000 times e.g. in taxi service in Europe, it should be inspected and replaced if appropriate.
April 30, 2004

500.000th Mercedes Actros with Telligent brake rolls off the line The Actros was introduced in 1996 and the second version in 2003 and became the workhorse in many truck fleets. Half a million have been manufactured. The brake system on the 1996 Actros was revolutionary using disk brakes, electronic control and the Telligent onboard data communications network. Telligent® brake system June 25, 2007

created Nov 2000 and updated from time to time

credits: Spiegel, DaimlerChrysler, Bosch, MBUSA, NHTSA

Es soll die Kunst des Bremsens perfektionieren. - Jürgen Pander

Wolfgang's ML Page