24.09.2021 - Automotive Spare Parts Turkey
Automotive Spare Parts Turkey

What is the brake system? What is the brake center? How to Identify the Brake Center Malfunction

What is the brake system? What is the brake center? How to Identify the Brake Center Malfunction

What is the brake system?

The braking system is one of the most important active safety systems that allows the vehicle to decelerate or stop safely.

What is the duty of the brake system?

To reduce the speed of the vehicle,
To stop the vehicle,
The standing vehicle is fixed in place (handbrake).

How Does the Brake System Work?

Braking is the process of converting the kinetic energy of the vehicle in motion (heat energy) into heat energy. The movement energy of the vehicle turns into heat energy generated by the friction of the pontoons and the vehicle slows down or stops.
When the driver depresses the brake pedal, this pushing motion is transmitted to the brake servos with a push rod, the brake pedal engagement acts like a lever and is transmitted to the brake servos with increased thrust. The braking servo is transmitted to the piston rod in the main brake center, which is immediately in front of it, further increasing this pushing force of the driver. Hydraulic brake fluid is located in the brake center.

With the pushing action of the driver with the pedal push and with the servo, the pistons in the brake center pressurize the hydraulic fluid (with greater force), through the hydraulic pipes and hoses, to the brake cylinders in the wheels and to the pistons in the calipers.
Brake calipers are available for disc brakes. The pressure hydraulic fluid pushes the piston in the cylinder in the cauldron towards the disco, there is a brake pin in front of the piston, the disk fixed to the center of the wheel slows down, the wheel slows down or stops. There is a wheel brake cylinder in the drum in the brakes.

The operation of the hydraulic brake is based on the pascal principle.

Electronic braking systems have been added to the hydraulic braking systems with improved technology and operation has been improved. These are ABS, ASR, ESP, etc. additional systems. In the new generation vehicles, the ABS system is offered as standard and the use of the ESP system is becoming widespread, with a large number of sensors and actuators added to the brake system in the brake system.

In today’s mid-range passenger cars and light commercial vehicles (van-doblo vehicles), disc brakes are usually used on the front wheels and drum brakes are used on the rear wheels. However, the use of disc brakes in 4 wheels has become increasingly widespread in vehicles manufactured by 2016.
Pneumatic braking systems are used in vehicles such as heavy trucks and buses.

What is the Brake Center What Works;

The brake center is the part that sends the force applied to the brake pedal by the driver to the wheel brake mechanisms by converting it into hydraulic pressure. Hydraulic pressure created in the brake center cylinder, caliper in disc brakes; the wheel is sent to the brake cylinder in the brakes.
The brake center pump is located directly in front of the brake servo and the brake hydraulic reservoir box is located at the top. The brake center cylinder takes the brake fluid from here and the hydraulic return from the brake line returns to this tank again.

What are the duties of the brake center?

To ensure the rapid formation of hydraulic pressure in the brake line,
Rapidly lowering the hydraulic pressure at the end of braking and releasing the brake,
To compensate for volume changes in the brake hydraulic fluid due to temperature differences,
Finish the brake fluid in the brake line so that there is no space in the resulting brakes when the brake pads are worn.

Brake Main Center Working Principle

Without Brake Pedal:
In this case, the transition channels from the brake fluid reservoir to the brake center cylinder are open. The two return bows in the cylinder push back the pistons.
From the brake fluid reservoir, two chambers in the cylinder are connected by two transition chambers. The bigger channel is called “inlet channel – inlet hole”, which provides oil rein to the cylinder from the hydraulic reservoir.
The second and narrower channel is called “compensating channel – balancing hole”. According to the pressure change in the brake line, brake fluid is sent from the reservoir tank or the brake fluid is returned.

Brake pedal depressed:
When the liquid in a closed container is compressed with a piston (the liquids can not be compressed), pressure builds up in the liquid and this pressure is applied evenly to each surface in the container. In the brake center cylinder, the driver applies the brake pedal, the pedal push rod is transmitted to the brake servo, and this pushing force is increased in the brake servo.
The push rod at the exit of the brake servos pushes the first piston in the center cylinder of the brake forward and as the piston moves forward, it creates pressure in the brake fluid in the front chamber and this pressure pushes the second piston forward in the hydraulic oil and forms the hydraulic pressure sent to brake line 1.
As the first piston pushes forward, the second piston also moves forward, creating pressure in the front brake fluid. The resulting pressure is sent to the 2nd brake line. Thus, hydraulic oil pressure is sent to the caliper piston in the wheels or the brake cylinder in the drum and the braking is applied.
The output lines of the brake center pump (central cylinder) have control valves. These control valves allow passage from the brake center pump to the wheels, but when the brake pedal is released, when the brake pedal is released, the hydraulic oil is always ready at a certain pressure in the brake line when the brake pedal is not depressed it is kept waiting.
In the braking system with ABS, the hydraulic pressure created by the master cylinder of the brake is sent to the ABS hydraulic module instead of the wheels and is distributed to the wheels in this hydraulic module.

When the brake pedal is released:

The driver pulls the foot off the brake pedal and releases the pushing force to apply the brake to the main center cylinder piston. Pressurized hydraulic brake fluid is no longer sent to the brake system. The return springs in the brake center cylinder push back the pistons (to their previous positions). The brake fluid in the brake line returns to the reservoir tank.
When the brake pedal is released, the balancing channel performs an important function. When the brake pedal is released, the pistons are quickly retracted, but the pressurized brake fluid in the system does not return so quickly. In this case, a vacuum (low pressure) occurs in the center cylinder, resulting in a rapid volume increase in the chambers in front of the pistons. This channel, when the brake pedal is released, is the result of the return spring pushing the piston suddenly backwards, the vacuum formed in the chamber balances by sending hydraulic oil here. When the piston returns to its normal position, the pressurized hydraulic oil still present in the brake line is returned to the reservoir tank from this channel.
In addition, when the volume of the hydraulic brake fluid that expands with temperature increases, it flows back into the reservoir box through the balancing channel and the pressure build-up in the cylinder is prevented.

How to Identify the Brake Center Malfunction

If the brake remains pressed;

Hydraulic oil inlet and return parts are available at the brake center. When you press the brake pedal under normal conditions, the brake pistons move and braking occurs. When you release the pedal, the hydraulic oil in the pistons is pushed back to the reservoir by pushing back. If there is a problem with this mechanism, probable causes may be that the drain hole is clogged and the brake pistons are stuck. Probably the main brake center may be defective. Rarely, brake hoses can cause problems with brakes.

If the brake does not hold at all:

As is known, the brakes keep the pressure of the hydraulic oil to the brake discs by means of pressure on the caliper through the brake lining. This pressure is also supplied by pressure hydraulic. If there is a leak in the system that will reduce the pressure, the brake performance may be completely reduced in half, and it may come to a standstill. Another scenario is that there is air in the braking system. This is usually caused by hydraulic oil falling below the critical level. The presence of air in the brake centers prevents the pressure oil transferred by the pedal movement from reaching the brake centers and not braking. One last possibility is a fault in the main center. Although it seems very rare, in some cases, the incorrectly installed bumper disk blanket can cause the brakes to be kept slightly low.

If the vehicle is rolling on the press, if pulling:

One of the most common failures is that the vehicle is steering towards the press. This is due to the fact that the brakes do not hold the same intensity on each wheel. If there is a blockage in the brake hydraulic hoses, it will pull towards the opposite side of the blocked side. If there is no full braking performance on the right side, the vehicle will pull to the left when you press the brake pedal. Another possibility is that the brake centers are failing. This can happen unilaterally. The incorrect setting of the braking system, especially for the braking system, will cause each wheel to have different braking values. In addition, defects that may occur in brake pistons and possible oil leaks may cause problems. Check whether there is a decrease in the brake fluid level.




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