Pressurizing piston unit, design - GF42.45-P-4200-02A
WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.
There are two separate pressurizing pistons (b) which are held in their normal position by the springs (d) in the cylinder housing (a) of the pressurizing piston unit. When the pressurizing piston is in this position, the central valves (c) of both control circuits located at the end face are opened.
The ESP brake pressure sensor (B34) is attached to the pressure chamber for the front axle circuit.