Mercedes S-Class W-140

1991-1999 of release

Repair and operation of the car



Mercedes S-Class
+ Mercedes-Benz cars of the class S (W-140)
+ Operation manual
+ Routine maintenance
+ Engine
+ Cooling systems, heating
+ Power supply system and release
+ Engine electric equipment
+ Gear shifting box
+ Automatic transmission
+ Coupling
- Brake system
   Specifications
   Arrangement of components of the ASR/ETS traction control system
   Arrangement of components of the amplifier of emergency brake application (BAS)
   Arrangement of components of the ESP system
   Dismantling and assembly of the "Tandem" main brake cylinder (MBC) (model 140.028/032/033/135)
   Removal, installation and check of serviceability of functioning of the servo-driver of the vacuum amplifier of brakes
   Removal and installation of a brake support
   Check of thickness of a brake disk and overlays of brake shoes
   Removal and installation of blocks of the parking brake
   Removal and installation of a forward cable of the drive of the parking brake
   Adjustment of the parking brake
   Wheel ABS sensors - installation details
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment






Brake system

General information and security measures

General information

The hydraulic brake system consists of the main brake cylinder, the amplifier of a brake and disk brakes of forward and back wheels. The brake system has two contours. One contour influences forward brakes, another - on back. At refusal of one of contours, for example, owing to liquid leak braking of the car is carried out by other contour. Liquid pressure in both contours is created by the doubled main brake cylinder operating from a brake pedal.

The description of work of systems of anti-blocking of brakes of ABS, the amplifier of emergency brake application of BAS and the electronic program of stabilization of stability (antistrange system) is provided in the Section Operation manual.

The tank with brake fluid is under the main brake cylinder, it supplies with liquid all hydraulic system of braking.

The amplifier of a brake accumulates a part of the vacuum created in the soaked-up engine pipeline. As the diesel engine has no necessary vacuum on absorption, cars with the diesel engine have the special vacuum pump. By means of the corresponding valve if necessary the effort to pedals of a brake increases thanks to effect of vacuum.

The parking brake with the pedal drive influences through cables brakes of back wheels. As as the parking brake the disk brake does not work, on back wheels the drum brakes which are built in disk brakes are in addition established. Drum brakes are put in action only from a pedal of the parking brake.

Security measures

When cleaning the brake system dust which can do harm to health of the person therefore it is impossible to inhale brake dust is emitted.

Work with the brake system demands special purity and exact observance of instructions. In the absence of necessary experience it is expedient to address on HUNDRED.

At movement along wet roads it is necessary to press periodically a brake pedal for removal of moisture from disks of brakes.


In the course of rotation of a wheel moisture under the influence of centrifugal force is dumped from brake disks, but there is a silicone film, rubber attrition products, lubricant and other pollution reducing efficiency of brakes.
After installation of new brake shoes the last have to be earned extra. Therefore the first 200 km of a run should not be braked needlessly strongly.

The disk brake mechanisms damaged by corrosion when braking create the effect of jolting which is not disappearing over time. In this case it is necessary to replace brake disks.

And rain flutes lead burning of dirt to a surface of brake shoes to formation of furrows on a surface of brake disks that leads to decrease in efficiency of braking.