The company's engineers paid special attention to the rear brakes. The diameter of their brake discs is 278 mm, which is 20 mm larger than on the previous model. The diameter of the front brake discs has increased by 4 mm.
The thickness and surface of the front brake pads have also been increased, which has significantly increased their service life. The front wheels are equipped with disc brakes with a floating caliper. E-class models are equipped with an electronically controlled ABS system as standard.
The most important elements of the service brake system
Dual-circuit braking system. The braking system is divided into two independent circuits. The first is responsible for braking the front wheels, the second - the rear.
Twin Master Cylinder. Converts mechanical force on the brake pedal into hydraulic energy and ensures rapid pressure reduction in the system when the brake pedal is released.
Brake fluid reservoir. It is located above the master cylinder and supplies the system with working fluid.
Brake booster. Uses part of the vacuum created by the engine at the intake.
Foot operated parking brake. It is activated by a cable system and applies the rear brakes. Since disc brakes are poorly suited to perform the parking brake function, drum brakes are additionally installed on the rear wheels, integrated with the main disc brakes. The drum brakes are activated only by the parking brake pedal.
Brake discs. Together with the wheels, steel brake discs connected to them rotate in the air flow. The so-called brackets are installed above them. When you press the brake pedal, the pistons, moving out of the brake cylinders, move the brake shoes with linings in the direction of the disc and clamp it - braking occurs.
Brake caliper. A mechanism in the form of a bracket, as if mounted on a brake disc.
Brake fluid
Brake fluid is light yellow, poisonous, aggressive to paintwork, neutral to metal and rubber parts. It remains liquid even at –40°C and has a very high boiling point – about +260°C.
The disadvantage of brake fluid is its hygroscopicity. Water can penetrate into the brake fluid, for example with moist air – through the reservoir or microscopic holes in the brake hoses and rubber cuffs. The water content in the brake fluid not only leads to corrosion of the metal parts of the system, but also significantly affects the reduction of the boiling point. Already at a 2.5% water content, the boiling point decreases to +150°C. With a strong load on the brakes, this can be dangerous, because the brake mechanisms get very hot. Near the hot brakes, steam bubbles can form in the fluid, which reduce the pressure in the system and can lead to the brake pedal "failing" when pressed. In such cases, you should quickly press the brake pedal several times to increase the pressure in the hydraulic system.
The effect of vaporization is especially dangerous when the car is parked after sudden braking. In the absence of cooling from the oncoming air flow, the working units of the brake system heat up even more, the maximum temperature is maintained for 15 minutes after stopping, and only after half an hour does the brake fluid cool down to normal temperature.
The scheduled maintenance plan includes replacing the brake fluid every two years (minimum requirement for DOT 4 specification). In this case, you should only use the brake fluid recommended for your model by the vehicle manufacturer.