ABS system. Anti-lock system: purpose, device, principle of operation. Bleed the brakes with ABS

Brake systems of cars, characterized by high efficiency, in some cases can lead to the occurrence of accidents. This is due to the fact that with a sudden braking the wheels are completely blocked, and the grip with the roadway disappears. And not always the inexperienced driver manages to cope with the car and quickly reduce the speed. To prevent disruption and skidding of the wheels, you can intermittently apply the brake. There is also an ABS system that is designed to prevent dangerous situations while driving. It improves the quality of adhesion to the roadway and maintains the controllability of the car, regardless of the type of coating.

Principle of operation

The mechanism of the system can be compared with the actions of an experienced driver. This is especially noticeable when ice rims, when the wheels are on the verge of blocking. In addition, it is worth noting the automated distribution of braking forces and the preservation of transport stability.

The operation of the device is based on the effect of the brake fluid on the mechanism of the wheels. This contributes to the appearance of braking force at the point of contact of the road and the wheels. The increase in this effect occurs only up to the established moment, otherwise slip increases due to the stopping of rotation.

This is what often becomes the reason for the loss of control by an automobile owner. The control unit of the device receives signals from the respective sensors, after which the pressure in the braking system decreases, and the degree of depression of the pedal does not matter.

What you need to know

The ABS system of the car has one distinctive feature, which consists in determining the braking of each wheel individually. Normalization of the fluid pressure occurs immediately after the movement becomes more stable. It is worth noting that driving a car without ABS and equipped with this system has some differences. In the latter case, you can safely press the brake, not worrying about the probability of blockage. This is especially important for drivers who have little experience and for the first time encounter such a supplement.

Bleed the brakes with ABS

Before you start to work, it is worth paying attention to the thread of the union. If it contains traces of rust, it is necessary to treat the surface with a special compound, this will prevent damage to the thread.

A transparent hose is put on the cylinder fitting, the other end of which is lowered into the container. The gear lever must be in neutral. The brake pedal is applied before the resistance starts. In the process of holding the pedal unscrew the choke, after it must come into contact with the floor. You can only release it after tightening the union. In the process of work is of particular importance the regular addition of brake fluid, this will prevent the penetration of air into the circuit.

Checking the quality of work

Bleeding the brakes with ABS is done on each wheel. In this case, there should not be the smallest bubbles in the brake fluid. The last step is to check the free running of the pedal and add fluid to the required level. It is also worth checking the tightness and tightness of each of the parts.

The performance can be checked by pressing the brake pedal for 15 seconds with the engine running. At this time, for a few seconds, the indicator indicating self-diagnosis should turn on. If nothing happened, this indicates that there is a malfunction of the ABS system. Arrival with systematic braking will allow to evaluate the quality of work.

Design

The system consists of several basic elements:

• Hydraulic block;
• Electronic control unit;
• Wheel speed indicators.

As a rule, the sensors work on the electromagnetic principle. They consist of a coil with a special core. The magnetic current inside the sensor changes due to the movement of the gutters and crown teeth during the rotation of the wheel. The electronic control unit receives incoming signals and determines the speed of rotation. With the help of special tables, the computer calculates the optimal braking algorithm, the maximum brake pressure and the quality of the road surface. In the control unit are modulators, which determine the appropriate level of pressure for the wheels. If a malfunction occurs, the Malfunction Indicator lights up, which informs the driver that ABS diagnostics are required.

Advantages

Its distribution system ABS has acquired due to the presence of many advantages, which include the following:

• There is no need to study the various modes of inhibition;
• The gas pedal does not require intensive monitoring, which is especially important for novice drivers;
• Exercise maneuvers with simultaneous braking;
• The possibility of braking on any part of the turn.

disadvantages

Despite the convenience of use, the anti-lock braking system of the car is not capable of becoming a panacea for all road troubles associated with braking. It is not devoid of negative aspects, including the absence of the possibility of use in maneuvers under extreme conditions. Also worth noting the following:

• There is a possibility of a delay in the inclusion of the system, since its full-scale operation is possible only after determining the coefficient of traction of the wheels and pavement and testing the quality of the blade;
• The driver does not control the braking process, which causes the ABS anti-lock brake system to become unpredictable;
• The coefficient of adhesion can be calculated incorrectly with frequent changes in uneven road coverage, which reduces efficiency;
• The ABS system does not operate at a speed of less than 10 km / h, this is especially true for heavy or armored vehicles, since in this case the braking distance significantly increases and there is a probability of an accident;
• The complexity of operation on loose and loose ground due to the elimination of the slightest blocking of the wheels.

In use, it is necessary to take into account all the features and disadvantages. The ABS system is designed to provide full control of the car during a sudden braking. Thus, the driver can confidently drive the vehicle and be able to maneuver during braking. The combination of these factors makes the system an effective assistant on the road and increases the safety of the driver and passengers. The car owner, who has sufficient experience, is able to cope with complex situations and without the help of the system, but it is indispensable for inexperienced drivers.

Diagnostics

In the event of a malfunction, the ABS system of the car immediately stops working, because of what the limitations in the braking system of the car disappear. The driver can find out if there is a problem with the warning light on the front panel. Diagnosis can be carried out in several ways, depending on the version of the device and the year of manufacture. The most common cause is the failure of the fuses.

First you need to inspect the shoe and make sure there are no damages. Also it is worth paying attention to the condition of the conductors and connectors. They must have a tight fit and a flat surface, without scuffs and scratches, which can cause a short circuit.

Suspension of the bridge (support and additional joints) and bearings should be checked for the presence of play and quality of performance. Particular attention is paid to the high-pressure pump. It is necessary to disconnect the connector and apply the voltage from the battery for a short time to the pump. To do this, you can use two conductors of any type. If it starts working, you can proceed with further examination.

Sensors

On the sensor speed sensors and their elements, there should be no traces of damage and stains. It is worth noting the increasing popularity of sensor active sensors. This is due to the presence of many advantages that passive analogs can not boast of. They are characterized by greater accuracy of the signal and the ability to determine the speed in two directions with maximum accuracy. Devices with similar measurement accuracy are used in various systems, including anti-theft devices and satellite navigation. Their indisputable advantage is the compactness of performance.