The pressure in the circuits is created by the brake pedal through the brake master cylinder.
The brake fluid reservoir is located in the engine compartment above the master brake cylinder and supplies brake fluid to the entire brake system.
The vacuum brake booster in a car with a gasoline engine works due to the suction vacuum created by the engine. The force of pressing the brake pedal is amplified by the vacuum in the intake manifold through the valve system. On vehicles with a diesel engine, the vacuum for the brake booster is generated by a vacuum pump. The vacuum pump is flanged to the engine block at the rear left and is driven by an intermediate shaft.
The brake discs are equipped with a floating caliper. With this design, only one piston is required to press both brake pads against the brake disc.
The parking brake acts on the rear wheels via a cable drive.
Attention
- When driving on wet roads, it is recommended to depress the brake pedal from time to time to remove harmful moisture and dirt from the brake discs. Due to centrifugal force, water is discharged from the brake discs during movement, but a thin film of fats, silicones, rubber residues, grease and dirt remains on them, which reduce braking efficiency. When stopping the vehicle after driving in the rain at the end of the journey, it is recommended to dry the brakes by depressing the brake pedal.
- Soot deposits on the surfaces of the brake linings and rain moisture penetrating the inside of the linings lead to the formation of scratches on the brake discs. As a result, the performance of the brakes may deteriorate.
ABS/EBV/ASR/ESP
ABS: Anti-Blokier-System - Anti-lock braking system that prevents the wheels from locking during heavy braking. This reduces the braking distance, especially when grip is low in rain and snow. The grip force between the wheels and the road in this case is greater when the wheels continue to rotate during braking. In addition, even with full braking, the car remains steerable.
EBV: Bektronische Brems-kraftverteilung - electronic brake force distributor, which distributes the brake force to the rear wheels using the ABS hydraulic system. The brake force distributor performs the functions of a mechanical pressure regulator, while its operation is more efficient and has a larger adjustment range. When driving in a straight line, all braking power is transferred to the rear wheel brakes. For stable cornering with braking, the supply of brake fluid to the rear brakes is limited. The EBV control unit uses signals from the ABS wheel speed sensors to determine when the vehicle is cornering. When driving in a turn, the braking force on the rear wheels is reduced. This transfers maximum lateral force to the rear wheels, reducing the likelihood of the rear of the vehicle skidding.
EDS: Elektronischen Differentialsperre - electronic differential lock - when starting off and accelerating, the spinning wheels are braked. In this case, a higher torque is transmitted to the wheels with the best grip.
The electronic differential lock works when the vehicle starts and is automatically disengaged when the vehicle speed exceeds 40 km/h. In this case, the increase in tractive effort consists in the fact that in the start-up mode the system does not adversely affect the driving mode of the vehicle and the driving comfort.
ASR: Antriebs-Schlupf-Regelung - the system for reducing the torque transmitted to the drive wheels, by removing engine power, reduces the drive torque when both drive wheels slip by reducing engine power.
When the EDS applies the brakes to improve traction, the ASR provides additional contact with the engine management system if necessary, and when the drive wheels slip, the engine power is limited so that only the torque necessary to move the vehicle is transmitted.
The purpose of the ASR is to increase active safety through stable driving and vehicle controllability, including when cornering, regardless of the degree of depression on the accelerator pedal. ASR works from the moment of starting, up to the maximum speed of the car.
ESP: Elektronisches Stabilitat-sprogramm - an electronic stabilization program, with the help of automatic action on the brakes, excluding lateral skids of the car. The electronic stabilization system combines anti-lock brakes and slip systems. The electronic stabilization system also measures yaw rate, lateral acceleration, brake pressure and front wheel steering. Based on the steering amount of the front wheels and the speed of the vehicle, the direction of the vehicle is determined and is constantly compared with the actual direction of the vehicle. In the case when the car begins to drift or skid, the stabilization system automatically slows down a certain wheel.
Notes regarding ABS/EBV/EDS/ASR/ESP
The emergency shutdown system ensures that the system is turned off in case of any malfunction or low voltage in the vehicle's electrical network (less than 10 V). The electronic control device also performs an auto-diagnostic function, warning the driver by illuminating a control lamp about the registration of a malfunction of electrical circuits or system elements. If the ABS system is faulty, the brakes are still functional and function as if the system were not in the car.
Safety Notes
If the ABS and brake system warning lamps are on while driving, the rear wheels may lock up during heavy braking due to the fact that the brake force distributor does not work.
If one or more warning lamps in the instrument cluster come on while driving, do the following:
- stop the car, turn off the engine and start it again;
- check the voltage at the battery terminals, if the voltage is below 10.5 V, charge the battery;
- check the reliability of the fastening of the wire clamps on the battery terminals and for the absence of unreliable contact;
- raise the car, remove the wheels, check the wires going to the speed sensors for external damage. Further testing of the ABS/EBV/EDS/ASR/ESP devices must be carried out at a workshop.
Attention
- If the control lamps light up immediately after starting the engine, and go out again after a while, this indicates that the battery voltage was lowered and then increased as a result of charging from the generator.
- Before welding with arc welding, disconnect the electrical connector of the electronic control unit. Disconnect the connector only when the ignition is off. When carrying out paint and varnish work, it is not allowed to expose the control device to temperature loads: for a short time - no more than +95°C, for a long time (no more than 2 hours) +85°С.
Pic. 11.1. Brake system diagram
1 - ASR switch,
2 - brake light switch,
3 - rear left wheel speed sensor,
4 - rear right wheel speed sensor,
5 - speed sensor of the right front wheel,
6 - left front wheel speed sensor,
7 - ABS/EBV/EDS/ASR/ESP control unit,
8 - control lamp ABS / EDS,
9 - control lamp ASR / ESP,
10 - brake fluid level control lamp,
11 - brake master cylinder, vacuum brake booster and brake pedal,
12 - hydraulic block.
Pic. 11.2. Front brake company Teves FN-3
1 - brake hose,
When replacing brake pads, do not unscrew the brake hose.
2 - protective cap,
3 - guide pin, 25 Nm,
4 - brake pipeline, 15 Nm, Screw the brake pipeline to the caliper.
When connecting the brake pipe and brake hose, hold the hexagon on the brake hose. Check the correct position of the locking tabs in the recesses of the bracket.
5 - support,
6 - bolt with ribbed head base, 120 Nm,
Before screwing in, clean the ribbed base of the bolt head.
7 - caliper holder,
8 - brake pads,
External brake pads have adhesive backings covered with a film that must be removed prior to installation.
It is necessary to replace all brake pads on one axle of the car at the same time.
9 - fixing spring,
The spring is installed in two holes in the caliper.
10 - brake disc,
If replacement is necessary, replace both front brake discs. Before removing the brake disc, the caliper must be removed.
11 - bracket,
12 - bolt, 10 N·m.
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