OK mate,
The E, S, SL, SLR and for a while CLS class cars use SBC (Sensotronic Brake Control) so there is no mechanical connection between the pedal and the brakes this was a crap system and MB are in the process of phasing it out it was overly complex due to all the backups and things constantly went wrong in fact another recall is doing the rounds right now.
The SLK uses basically a normal master cylinder with vacuum assist and a sensor and solenoid to measure pedal travel and operate the diaphram when you press on the pedal you do move fluid like in an ordinary system and if the computer fails then the system will just feel very sloppy but you will still have hydraulic brake control when its working normally the ESP pump that sits between the pedal and the brakes uses its internal reservoir to control exactly how much pressure is applied to each individual brake.
So basically in normal operation the system is electronic the sensor on the master cylinder detects how far and fast you have moved the pedal and informs the ESP of the calculation it then operates the system itself as i explained above, the resistance you feel is provided by the ESP pump.
Sorry if it sounds a little fussy i will try and have a think of how to explain it better or will get the WIS sheet posted up or something but basically imagine 2 systems a low pressure and a high pressure with the one constantly keeping the other topped up hence the need for the servo to activate the diaphram in BAS mode to keep the pressure correct.
__________________ One thing you will learn with German cars - If it's simple it ain't happening. |