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General information and safety measures
The brake system consists of a master cylinder, vacuum booster and disc brakes front and rear wheels, and is divided by a diagonal pattern on two independent hydraulic circuits. When failure of any of the circuits (for example as a result of pressurization failure) continues to operate in the second normal mode, providing adequate braking of the vehicle. Additionally, the contours of both rear brakes integrated pressure regulator valve provides a dynamic correction braking force of rear wheels in accordance with the change of the load on the rear axle of the vehicle. The fluid pressure in both circuits have created the tandem master cylinder design (GTZ). Activation occurs when the GTZ squeezing of a pedal of a foot brake. Scheme of the hydraulic drive of brake mechanisms A brief description of the principles of functioning of auxiliary electronic systems of anti-lock brakes (ABS), strengthen emergency braking (BAS), brake force distribution (EBV), traction (ASR / 4-ETS) and protivozanosnoy (ESP) is given in Chapter Controls and receptions of safe operation. Arrangement of system components to strengthen emergency braking (BAS) Arrangement of auxiliary components of electronic systems ASR / ETS / ESP Brake fluid reservoir is located under the main brake cylinder, it supplies the entire hydraulic brake fluid. Power brakes accumulates part of the vacuum created in the intake manifold of the engine. Since the diesel engine is not required vacuum suction, diesel cars have a special vacuum pump. Using an appropriate valve if necessary, brake pedal force is increased due to the action of the vacuum. Parking brake pedal actuator acts via cables to the rear brakes. Additionally, the rear brakes are equipped with drum units handbrake pedal-operated rope. The principles of functioning of auxiliary systems ABS / 4-ETS / ESP / EBV Electro-circuit operation support systems represented in the figure, which includes all the links in the text. Driving auxiliary hydraulic circuit electronic systems ABS / 4-ETS / ESP / EBV The structure hydromodulator auxiliary braking systems (A7 / 3) includes components of the closed loop system dynamic control systems, ABS, 4-ETS / ASR and ESP. Pressure and return pump (A7 / 3m1) Self priming discharge and return pumps (p1, p2) are integrated into an assembly hydromodulator (A7 / 3) and are switched in the phases of pulse signals pressurizing and depressurizing system and active control ETS ESP, and during adjustment backflow ABS activation. Self priming discharge and return pumps (p1, p2) are triggered as necessary to minimize the noise level. Each brake circuit is equipped with a separate damper (10), reduces the level of noise produced by the pump. Solenoid valves retention (intake) and discharge (discharge) pressure (A7 / 3y6 - A7 / 3y13) A 2/2-way valve is used for pressure control in circuits of each of the wheels in the phases of the injection / hold and hold / reset control mode, ABS, ETS and ESP. Low-pressure accumulator (11) Low-pressure accumulator (11) is filled with brake fluid phase pressure relief ABS, ETS or ESP and ensures its transmission to the pressure-return pumps (p1 / p2). Multiport control solenoid valves (A7 / 3y24 and A7 / 3y25) Solenoid valves multiport switches (y24 and y25) provides active pressure cutoff diagonal contours of the GTZ in the functioning of the ETS and ESP. Also provide pressure relief valves when lifting it above 150 atm. Passed through a switching valve brake fluid is sent back to the GTZ. Solenoid valves are pre-filling (A7 / 3y26 and A7 / 3y27) Valves (y26, y27) opened in phases of pressure rise ETS / ESP. The principle of operation of the sensor assembly points in leading away / transverse accelerations ESP Sensors leading away torque and transverse stresses in order to save space combined into a single assembly (B24 / 2). Micromechanical sensor assembly converts the lateral and vertical projection of the angular accelerations into electrical signals. Various mass operating elements under the action occurring during irregular motion of the vehicle (acceleration and cornering) overloads provide varying degrees of deformation. Special electronic converter converts the received signals and transmits them via CAN to the control module and protivozanosnoy traction systems (N47). The sensing element leading away from the moment the micromechanical ring (a), equipped with eight spring webs (b), providing its movement and Electromagnetic action. Upon rotation of the assembly have additional Coriolis force proportional to the speed of rotation and electromagnetically latched after conversion module ACIS in the form of analog signals issued by the control unit of the instrument cluster. The construction of a capacitive sensor leading away the moment the ESP The measuring principle is based on the transverse accelerations using spring-mass element with a capacitive detector. Operating voltage is supplied to the control unit ESP (N47-2). Encountered during cornering transverse displacement overload provide a spring-mass member from the equilibrium position an amount proportional to the value of reaction force arising. Any change in the position of the element leads to a change in the capacitance detector. Next, note the amount of deviation is converted into a signal voltage, allowing the control module ESP (N47-2) quantify the values recorded by the transverse loads. The electronic control unit ensures that the system, in the event of mechanical damage to the circuit (eg, cable break) or too much voltage drop is automatically disabled. The situation is displayed on the instrument panel warning lamp activation of the ABS. Simultaneously off the ESP and BAS, as evidenced by triggering the corresponding indicator (see chap. Controls and receptions of safe operation). The main brake system continues to maintain its performance at the same time - during braking the car behaves as if no ABS system. Activating while driving ESP warning lamp indicates failure detection brake assist system (BAS) or protivozanosnoy system (ESP), - appropriate systems while also maintaining the ability of disabled operation of the main brake system. When activated while driving the red control lamp of brake system, you must stop immediately and try to find out the reason to establish a violation, which may in particular be a drop in the brake fluid level, or not fully released the parking brake lever. Procedure control lamp ABS is activated while driving Stop the car, stop the engine and restart it. Check the battery voltage - if the measurement is less than 10.5, make recharging the battery.  | If the ABS warning lamp lights up at the beginning of the motion, and then some time later extinguished, it indicates a low battery voltage, which increases after the start of operation of the generator. |
Make sure of reliability of fastening of tips of wires on the pole terminals of the battery, if necessary, tighten the fasteners. Poddomkratte car and establish it on props, remove wheels and check the speed sensor wiring. More detailed diagnosis should be carried out in a service station with special equipment for reading stored in the memory control unit fault codes (DTC). security measures - Brake fluid is among the highly toxic and chemically aggressive compounds, and in contact with the body panels destroys the paintwork!
- Brake dust generated in the process of wear of the brake pads may contain harmful to human health asbestos - in any case, do not inhale it when cleaning the brake!
- Work on the brake system requires a high purity and precision of instructions. In the absence of the necessary experience it is advisable to contact the service station.
| When driving on wet roads need to periodically press the brake pedal to remove moisture from the brake discs |
- During wheel rotation moisture centrifugally discharged from the brake discs, but leave a film of silicone rubber attrition, grease and other contaminants that reduce braking performance!
- After installing new brake pads last have earned extra - try to avoid sharp braking the first 200 km of run after replacement!
- Corroded disc brakes provide braking effect of shaking, do not disappear with time, - replace the wheels!
- Dirt sticking to the surface of the brake pad lead to formation of grooves on the surface of the brake disk, leading to a reduction in braking performance!
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