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 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 significantly increased their service life. The front wheels have floating caliper disc brakes. The E-class models are equipped as standard with electronically controlled ABS.
The most important elements of the service brake system
Dual circuit brake system. The braking system is divided into two independent circuits. The first is responsible for braking the front wheels, the second - the rear.
Dual Master Cylinder. Converts mechanical force on the brake pedal into hydraulic energy and provides a rapid reduction in pressure in the system when the brake pedal is released.
Brake fluid reservoir. Located above the main cylinder and provides the system with working fluid.
brake booster. Uses part of the intake vacuum created by the engine.
Foot parking brake. It is actuated by a cable system and engages 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 actuated by the parking brake pedal only.
Brake discs. Together with the wheels, steel brake discs associated with them rotate in the air stream. Above them are the so-called brackets. When you press the brake pedal, the pistons, moving out of the brake cylinders, shift the brake pads with linings in the direction of the disc and clamp it - braking occurs.
Stopping support. The mechanism is in the form of a bracket, as if mounted on a brake disc.
Brake fluid
Brake fluid - light yellow, poisonous, aggressive to paintwork, neutral to metal and rubber parts. It retains a liquid state even at –40°C and has a very high boiling point of about +260°C.
The disadvantage of brake fluid is its hygroscopicity. Water can enter the brake fluid, for example with moist air, through the reservoir or microscopic holes in the brake hoses and rubber cuffs. The presence of water 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 2.5% water content, the boiling point drops to +150°C. If the brakes are heavily loaded, this can be dangerous because the brakes become very hot. Near hot brakes, vapor bubbles can form in the fluid, which reduce system pressure and can cause the brake pedal to pop when pressed «fall through». In such cases, 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 half an hour later the brake fluid cools down to normal temperature.
The maintenance plan calls for changing the brake fluid every two years (minimum requirement according to DOT 4 specification). When doing this, use only brake fluid recommended for your model by the vehicle manufacturer.