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ABS system. Anti-blocking system: purpose, device, principle of operation. Bleeding brakes with ABS

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ABS system. Anti-blocking system: purpose, device, principle of operation. Bleeding brakes with ABS
ABS system. Anti-blocking system: purpose, device, principle of operation. Bleeding brakes with ABS

The braking systems of vehicles, which are highly efficient, in some cases can lead to accidents. This is due to the fact that during heavy braking, the wheels are completely blocked, and traction disappears. And not always an inexperienced driver manages to cope with the car and quickly reduce speed. You can prevent skidding and blocking of the wheels by intermittently applying the brake. There is also an ABS system, which is designed to prevent dangerous situations while driving. It improves the quality of grip with the roadway and maintains controllability of the car, regardless of the type of surface.

abs system

Working principle

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

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

This is what becomes a frequent cause of loss of control by the car owner. The control unit of the device receives signals from the corresponding sensors, after which the pressure in the brake system decreases, while the degree of pressing the pedal does not matter.

What you need to know

The car's ABS system has one distinctive feature, which is to determine the braking of each wheel separately. The normalization of 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 without worrying about the likelihood of blocking. This is especially important for drivers who have little experience and are faced with such an addition for the first time.

car abs system

Bleeding ABS brakes

Before starting work, you should pay attention to the thread of the fitting. If there are traces of rust on it, 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 second end of which is lowered intocapacity. The gear lever must be in the neutral position. The pressure on the brake pedal is applied until resistance begins. In the process of holding the pedal, the fitting is unscrewed, after which it should come into contact with the floor. You can release it only after tightening the fitting. In the process of work, regular addition of brake fluid is of particular importance, this will prevent air from entering the circuit.

bleeding brakes with abs

Checking the quality of work

The ABS brakes are bled on each wheel. In this case, there should not be the slightest bubbles in the brake fluid. The last step is to check the free play of the pedal and add fluid until the required level is reached. It is also worth making sure that each of the parts is tight and tight.

Efficiency can be checked by depressing the brake pedal for 15 seconds with the engine running. At this time, the indicator should turn on for a few seconds, indicating that the self-diagnosis is being carried out. If nothing happens, this indicates that there is a malfunction in the ABS system. A race with systematic braking will allow you to further evaluate the quality of work.

abs diagnostics


The system consists of several main elements:

  • hydraulic block;
  • electronic control unit;
  • wheel speed indicators.

As a rule, sensors work on the electromagnetic principle. They consist of a coilspecial core. The magnetic current inside the sensor changes due to the movement of the grooves and teeth of the crown during the rotation of the wheel. The electronic control unit receives the incoming signals and determines the rotation speed. Using special tables, the ECU calculates the optimal braking algorithm, the maximum degree of braking pressure and the quality of the road surface. In the block control there are modulators that determine the appropriate level of pressure for the wheels. When a malfunction occurs, the malfunction indicator lights up, which informs the driver that ABS diagnostics are required.


The ABS system has gained popularity due to the presence of many advantages, which include the following:

  • no need to learn different ways of braking;
  • the gas pedal does not require intensive control, which is especially true for novice drivers;
  • execution of maneuvers with simultaneous braking;
  • braking at any part of the turn.


Despite its ease of use, a car's anti-lock braking system is not a panacea for all braking problems on the road.

abs system malfunction

It is not devoid of negative aspects, which include the inability to use when maneuvering in extreme conditions. Also note the following:

  • there is a possibility of a delay in turning on the system, since its full operation is possible only afterdetermining the coefficient of adhesion of wheels and road surface and testing the quality of the canvas;
  • the driver has no control over the braking process, which makes the ABS anti-lock system unpredictable;
  • Grip coefficient may be miscalculated if the road surface is changed frequently, reducing efficiency;
  • ABS system does not work at speeds below 10 km/h, this is especially true for heavy or armored vehicles, as in this case the braking distance increases significantly and there is a possibility of an accident;
  • difficulty of operation on loose and loose soil due to the elimination of the slightest blocking of the wheels.

When using it is necessary to take into account all the features and negative aspects. The ABS system is designed to provide full control of the vehicle during hard braking. Thus, the driver can confidently control 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. A car owner with sufficient experience can cope with difficult situations without the help of the system, but it is indispensable for inexperienced drivers.

abs anti-lock braking system


When a malfunction occurs, the car's ABS system immediately stops working, due to which the limitations in the car's braking system disappear. The driver can learn about the occurrence of a problem by signaling an emergencylamp installed on the front panel. Diagnostics can be performed in several ways, depending on the type of device and year of manufacture. The most common cause is a faulty fuse.

First you need to inspect the pad and make sure there is no damage. You should also pay attention to the condition of the conductors and connectors. They must have a tight fit and a flat surface, free of scuffs and scratches that could cause a short circuit.

Axle suspension (support and additional joints) and bearings should be checked for play and workmanship. Particular attention is paid to the high pressure pump. It is necessary to disconnect the connector and apply voltage to the pump coming from the battery for a short time. To do this, you can use two conductors of any type. If it starts to work, you can proceed to further inspection.

car anti-lock braking system


The RPM sensors and their elements must be free of damage and stains. It is worth noting the increasing popularity of touch active sensors. This is due to the presence of many advantages that passive counterparts cannot boast of. They are characterized by greater signal accuracy 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 undeniable advantage is their compactness.execution.

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