Vacuum brake booster. Braking

To date, brake boosters using vacuum are used on most types of vehicles. Through their design, these devices use vacuum to help boost the brake at the moment the pedal is depressed. The use of this type of booster increases the comfort and performance of the system, in other words, this device softens the force on the brake pedal for the driver. Let's look at the principle of operation of such a mechanism.

Scheme of operation of the vacuum brake booster

From a constructive point of view, the vacuum brake booster is assembled in a single unit, which contains a ringed glass in which the membrane is located, a special valve. Also, a pusher and a long rod are installed in the design, with the help of which the piston stroke is formed in the main brake cylinder. This design is crowned with a special spring, with the help of which the reverse action of the master cylinder is performed.

The block diagram of the vacuum brake booster is divided by a membrane into 2 chambers. The rear chamber on the side of the dashboard is called vacuum. Opposite this compartment is the front chamber, which is called atmospheric.

The main device of the vacuum brake booster

1. The vacuum chamber is connected via a valve to the main vacuum source through a hose. On gasoline car models, it is considered to be a source of back pressure, since the vacuum in a given volume is produced using. On diesel versions, the vacuum is taken using a special pump, which is attached to the engine camshaft and creates the necessary vacuum through a hose.

• On some vehicles, in order to use a constant vacuum supply pattern, engineers install a special electric vacuum pump that constantly provides the necessary vacuum flow to the converter cavity.
• Through the bypass channel, the main chambers are separated from the manifold (hose) side, and when the engine stops, the main valve leaves a vacuum in the cylinder itself.

This solution is very relevant from a safety point of view, since in the event of a pump failure, the driver will have a chance to completely stop the car.

1. The free chamber is connected by means of a floating valve in the following cases. With a vacuum chamber - in cases where this membrane is at its original point; as well as with the brake pedal depressed - with atmospheric pressure.

• A special pusher forms the movement of the follower valve, which is directly connected to the brake pedal.
• On the inside of the vacuum booster, the diaphragm is connected to the main rod of the brake cylinder. The operation of the main membrane ensures the movement of the piston, which in turn provides the necessary fluid pressure in the lines of the brake system.

1. The return spring is set in such a way that at the moment the pedal is released, the position of the diaphragm is restored to its original value.

On more modern cars, to effectively enhance the brakes, a special electrical device is used that increases the voltage on the diaphragm from the back. A hose is not required for this device.

1. The next step in the evolution of the brake booster is the active device. This device ensures uninterrupted operation of the amplifier only in those cases in which it is necessary, which gives this device special qualities. The active amplifier is installed together with the electronic stabilization system of the car and is an actuator for ensuring the stability of the car on the road.

The principle of operation of the vacuum amplifier

The basic principle of operation of such a device as a vacuum brake booster is based on the difference in pressure in its different cavities. At the moment when the membrane has a single location, the pressure in both cases is equal to the vacuum source. In the case when voltage is created on the brake pedal, an auxiliary effect is carried out, which, through a special rod, is transmitted to the floating valve. This valve closes the air channel that combines the atmospheric and vacuum zones.

The connection of the free chamber with the ambient pressure occurs at the moment when the further movement of the valve begins, this leads to a decrease in pressure in this chamber. The difference in vacuum pressure acts on the diaphragm, as a result, this assembly exerts force on the spring and moves the main piston of the brake cylinder.

The principle of operation of this auxiliary provides auxiliary forces on the piston rod of the brake cylinder, which are equal to the stress on the pedal.

In other words, this procedure can be described as follows. The harder the driver presses the brake pedal, the stronger the effect on the master brake cylinder will be.

After the driver has released the brake pedal, the free chamber is released from pressure, which helps to equalize the vacuum between the zones. With the help of a return spring, the main diaphragm returns to its original position and is ready to receive a new portion of the vacuum.

As a result of the operation of this mechanism, a certain force is created, which is 5-6 times greater than the pressing force of a person. For some cars, the manufacturer installs a vacuum brake booster, which is based on several membranes, which increases its performance several times. Of course, in addition to such a device, it is necessary to use a more powerful pump to provide the right amount of vacuum.

As for the repair of this device - it is impossible. Such a categorical statement is connected with the design and principle of the device of this mechanism, which provides the car with safety.

Conclusion

In the process of learning the production technology of the vacuum auxiliary, we have identified a number of some of the design features of this mechanism. As practice confirms, the vacuum brake booster has very durable properties and very rarely fails. The most vulnerable part of the brake system is the GTZ, which contains rubber seals. Also, we can note the vacuum pump, which is installed on diesel units and has a short service life, unlike the gasoline counterpart.

The vacuum brake booster (in the common people, a vacuum) is the most important design, the reliability of which determines the safety of the movement of a modern car, the purpose of which is high speeds.

To minimize the efforts of the driver when trying to stop or slow down a heavy vehicle, a vacuum brake booster is used, the principle of which is based on the use of vacuum. At the same time, its device is designed in such a way that even with a minimal effort on the pedal, a significant braking moment is created, which is transmitted by means of liquid flowing through special reinforced hoses to the pads. At the same time, the scheme of operation of the amplifier, as well as the design of the amplifier, may vary for cars from different manufacturers. However, the principle of operation, the basic idea of ​​using vacuum amplification of mechanical movement, remains unchanged.

Amazingly high efficiency

Be that as it may, the vacuum brake booster in a modern car is a unit without which it is difficult to imagine the entire structure as a whole. After all, the effort of a simple human leg is not enough to stop or slow down the movement of a multi-ton vehicle, sometimes rushing at a speed of more than a hundred kilometers per hour. And that's when this device comes to the rescue, which allows you to work out the entire system as a whole with a huge coefficient of performance (COP).

After all, the effort applied to the brake pedal in the cabin is so insignificant compared to how the same force works on the pads, that the effectiveness of the principle of operation of the vacuum brake device is obtained with a stunning effect, very rarely found in mechanics in general. And, probably, only a vacuum cleaner can provide such a high efficiency, which is required on modern cars, for which the reliability of the operation and operation of the brake system is probably the most important functional point.

Why is it needed

It is the vacuum booster that makes it possible that sometimes you can meet a fragile woman driving a multi-ton SUV, effortlessly coping with a multi-ton colossus. Moreover, modern brake boosters are designed, moreover, with a large margin of safety and service life, on which, in fact, the safety of the driver and passengers depends, it is extremely reliable. The vacuum booster is an extremely efficient (in a purely mechanical sense) design that makes a huge difference in the physical work done at the “input” to the brake system (the work of a human foot pressing the pedal in the cabin) and at its “exit” (the work of calipers pressing the pad to the disc). Therefore, the designers get the opportunity to make it so that even the smallest effort (consider a young fragile girl) can give a significant result.

Operating principle

The main thing in the node is the reliability of the design. In order to approximately imagine the principle of operation of a vacuum cleaner, one can imagine the operation of a mechanism in which air is supplied to the working storage tank during the operation of the car engine, eventually reaching high pressure. And this accumulated supply of air under high pressure, in fact, is fed into the system in portions, creating a significant effort. That, in fact, is the whole principle of operation of the vacuum brake booster.

It is for this reason that on VAZ cars, with the engine turned off, pressure on the pedal does not give such an effect, it seems that the brakes simply disappear, which in turn introduces inexperienced drivers into complete confusion. In fact, you just need to significantly increase the pressure, because the vacuum cleaner is not involved in the process.

As you can see, there are no special secrets in how it works. However, manufacturers usually treat the design of this unit with special care. It is understandable. For a modern car, which is designed to operate at high speeds, the reliable operation of the brakes is the most important circumstance. And in this regard, the design of the vacuum amplifier, of course, simply must be reliable.

The vacuum brake booster is the most common type of booster that is used in the brake system of a modern car. It creates additional force on the brake pedal due to vacuum. The use of an amplifier greatly facilitates the work of the car's braking system, and thereby reduces driver fatigue.

Structurally, the vacuum booster forms a single unit with the main brake cylinder and includes a housing, a diaphragm, a follower valve, a pusher, a piston rod of the main brake cylinder, and a return spring.

The amplifier body is divided by a diaphragm into two chambers. The chamber facing the master brake cylinder is called the vacuum chamber. The chamber opposite to it (on the side of the brake pedal) is atmospheric.

The vacuum chamber is connected to a vacuum source through a check valve. The area in the engine intake manifold after the throttle valve is usually used as a source of vacuum. To ensure uninterrupted operation of the vacuum booster in all operating modes of the vehicle, a vacuum electric pump can be used as a source of discharge. On diesel engines, where the vacuum in the intake manifold is negligible, the use of a vacuum pump is mandatory. The non-return valve disconnects the vacuum booster and the vacuum source when the engine stops, as well as when the vacuum pump fails.

Atmospheric chamber with a follower valve has a connection:

• in the initial position - with a vacuum chamber;
• with the brake pedal depressed - with the atmosphere.

The pusher provides movement of the follower valve. It is connected to the brake pedal.

From the side of the vacuum chamber, the diaphragm is connected to the piston rod of the main brake cylinder. The movement of the diaphragm moves the piston and pumps brake fluid to the wheel cylinders.

The return spring at the end of braking moves the diaphragm to its original position.

For effective braking in an emergency, the emergency braking system, which is an additional electromagnetic drive of the rod, can be included in the design of the vacuum brake booster.

A further development of the vacuum brake booster is the so-called. active brake booster. It ensures the operation of the amplifier in certain cases and, therefore, pressure build-up without the participation of the driver. The active brake booster is used in the ESP system to prevent rollover and eliminate oversteer.

The principle of operation of the vacuum brake booster is based on creating a pressure difference in the vacuum and atmospheric chambers. In the initial position, the pressure in both chambers is the same and equal to the pressure created by the vacuum source.

When the brake pedal is pressed, the force is transmitted through the pusher to the follower valve. The valve closes the channel connecting the atmospheric chamber with the vacuum one. With further movement of the valve, the atmospheric chamber is connected to the atmosphere through the corresponding channel. The vacuum in the atmospheric chamber is reduced. The pressure difference acts on the diaphragm and, overcoming the force of the spring, moves the piston rod of the master brake cylinder.

The design of the vacuum booster provides an additional force on the piston rod of the master brake cylinder proportional to the force of pressing the brake pedal. In other words, the harder the driver presses the pedal, the more efficient the amplifier will work.

At the end of braking, the atmospheric chamber reconnects with the vacuum chamber, the pressure in the chambers equalizes. The diaphragm moves to its original position under the action of the return spring.

The maximum additional force realized with the help of the vacuum brake booster is usually 3-5 times greater than the force from the driver's foot. A further increase in the amount of additional effort is achieved by increasing the number of chambers of the vacuum amplifier, as well as increasing the size of the diaphragm.

The vacuum brake booster is an integral part of the vehicle's braking system. In the common people, this type of amplifier is commonly called "vacuum".

It is designed to create additional reinforcement of the brake pedal, this is due to the discharge. Thanks to this type of brake booster, the functioning of the automotive brake system is greatly facilitated.

How is a brake vacuum booster arranged?

The vacuum booster of the brake system is a metal case, it is mechanically, as well as structurally connected to the GTZ, they are integral parts of one brake system. The amplifier body has two parts, into which the diaphragm divides it:

1. The first part of the amplifier is vacuum, it is located on the side of the main brake cylinder.
2. The second part is atmospheric, it refers directly to the brake pedal.

The vacuum-type brake booster, together with the GTZ, has the following components:

• Main body.
• follow-up valve.
• Diaphragm.
• Pusher.
• return spring.
• GTZ piston rod.

How does a vacuum unit work?

The vacuum chamber, which does not contain air, goes to the intake manifold, this is done using a special valve. Usually on modern cars, these include models no older than 2010, an electric pump is additionally installed, it is responsible for the stable operation of the vacuum booster.

At a time when the car's engine is not running, this special valve disconnects the brake booster from the manifold. Thus, when the engine is turned off, the brakes of the vehicle disappear for a while, cease to function. The same principle also works during the operation of the motor, even if the vacuum device is slightly damaged.

The second part of the vacuum unit, which can be called atmospheric, as we noted earlier, is connected to the second vacuum half with a valve. The operation of this valve is the basis for the functioning of the vacuum unit, since it creates different pressures between the two chambers of this braking device. When the engine is not running, and the driver does not press the brake pedal, the pressure in these two chambers - vacuum and atmospheric, will be the same.

When the driver just starts to press the pedal, the pusher moves along a specific trajectory, namely, to the servo valve, as well as the brake cylinder rod. With this movement, the valve closes the channel between the two parts of the unit that perform different functions.

In such a situation, in the vacuum part of the device, the pressure remains at the same level, and at that moment a vacuum occurs in the atmospheric chamber. When the braking process is completed, the spring will return the diaphragm to its original position.

What are the signs of a bad vacuum booster?

If the driver's vacuum brake booster suddenly stops working, there is no need to worry, there is a way out. You just need to apply a little more force on the brake pedal, and also control the vehicle with little effort.

You should seriously think about the complete replacement or detailed repair of the vacuum unit only in situations where it has partially or completely lost its functions.

Damage signs:

• The driver exerts more and more effort to depress the brake pedal, but the braking becomes weaker with each depress.
• If, during idle operation of the engine, it starts to "troit", while pressing the brake pedal, it works normally, keeps the desired rhythm.
• If a hose breaks or a crack has formed in it, this is usually accompanied by a loud hiss or other extraneous sounds that are uncharacteristic of the normal operation of the vehicle.
• During operation, the vacuum unit began to suck in air, even in a small volume.
• If a diaphragm rupture occurs, the rubber on the valves or seals is completely worn out.

Checking the vacuum booster

The brake system must always be in good working order, the safety of both the driver and his passengers depends on this. That is why it is worth being very sensitive to any changes in the functioning of the vehicle's braking system.

You should be alerted by clicks, crackling, grinding and other extraneous sounds. There are also other signs of a broken vacuum that an experienced driver will never ignore. Any driver, before setting off on a journey, especially a long-distance one, can independently verify that the vacuum cleaner is in good condition, even a beginner in the auto business can carry out such a check.

If the brake pedal is too hard, it is most likely caused by a vacuum in the intake manifold or a bad hose. It can also be caused by a defect in the vacuum booster itself or the control valve with which it is equipped.

How to check?

1. If your vehicle's engine is "throttling" but it only happens before you apply the brakes? This is usually caused by depressurization, in which air is sucked into the intake manifold. There is a sharp mixing of air with the fuel mixture, which enters the engine cylinders.
2. Turn off the engine of your car, press the pedal five to six times in a row. On the seventh application of the brakes, stop in the middle of the stroke. Do not release the pedal, start the engine at the same time. If at this moment the pedal falls to the floor, the unit is working. If the brake pedal does not change its position when starting the engine, it must be replaced or repaired.
3. If, when inspecting your car, you notice smudges that the brake fluid leaves, it is also worth contacting a car service.

Be careful and check the brake system of your car from time to time. Like any part of the machine, its operation requires control, brake failure is very dangerous, so you should carefully monitor their performance.

Today, the vacuum brake booster is one of the most important parts in the car. It is very convenient for the brakes, as it saves the driver's strength and facilitates the work of the car's brake system. Let's consider it in more detail and analyze the replacement of the amplifier using the VAZ 2110 as an example.

This mechanism consists of the following parts:

• Frame;
• Diaphragm;
• Valve;
• Pusher for brake pedal;
• Rod belonging to the brake hydraulic cylinder;
• Return spring.

It is round in shape, with a sealed housing, located in front of the brake pedal in the engine compartment. The bracket is attached to the body with four nuts, the bracket itself with the amplifier is connected with two nuts.

How a vacuum brake booster works

Its operating principle is based on the pressure difference in the vacuum and atmospheric chambers. In the initial position, the pressure is the same in both parts and is equal to the pressure of the vacuum source.

By pressing the brake pedal, you activate the transfer of force to another valve through the pusher. The valve then closes the channel between the vacuum and atmospheric chambers. After that, the valve continues to move, and the atmosphere and atmospheric chamber are connected. The vacuum decreases, as a result of which the pressure difference acts on the diaphragm and moves the piston rod of the brake cylinder through overcoming the force of the spring.

When braking ends, the atmospheric chamber is reunited with the vacuum chamber, the pressure in them equalizes, and the diaphragm returns to its original position. This design is exceptionally effective, as it makes it possible not to apply gigantic braking forces, but to get a significant result with a small pressure. That is why modern amplifiers are designed with a long service life, which ensures a high degree of safety for the driver and passengers.

When to change the brake booster and how much it will cost

Like any machine component, the amplifier needs to be replaced over time. The reason for its failure is the depressurization of the hose that connects the amplifier and the engine intake manifold.

There are several ways to check the amplifier for faults:

1. Start the engine, turn it off after a few minutes. Depress the brake pedal a few times with normal force. With a working amplifier, the pedal will be squeezed out to the stop. The second and subsequent pressing will reduce the pedal travel. If no difference is felt, then the device does not provide additional amplification in the main brake booster.
2. With the engine off, press the pedal several times in a row. We start the engine, a serviceable amplifier makes it possible for the pedal to drop a little due to the fact that the rod pulls the pusher behind it. Otherwise, the amplifier is defective and needs to be replaced.
3. The motor is running, we press the brake pedal, holding it, we turn off the car. If the amplifier is faulty, then the diaphragm, due to the lack of tightness, will raise the pedal, pressing on the pusher, which also indicates a malfunction of the vacuum cleaner.

Now let's say a little about the price of a vacuum brake booster for the VAZ 2110. Since this model is very popular, the cost can vary from 1000 to 3000 rubles, the average price will be around 1500 rubles.

You can also find used ones, but they are short-lived and will have to be changed more often, which will cost more than buying a new amplifier.

It is best to purchase vacuum boosters in spare parts stores, since you will receive a guarantee of the reliability of the part and will be able to examine it in all details, as well as choose the one that suits you in all the necessary parameters. If you place an order in online stores, you will have to face some waiting time for delivery. It is also worth preparing for the fact that you can run into low-quality goods and there will be a reason for proceedings, in order to avoid this, you need to order the part only from trusted suppliers.

How to replace the amplifier on the VAZ 2110 yourself

If you already have a new amplifier in stock and you know how to disassemble the components of a VAZ 2110 car, then you have the opportunity to independently replace the VAZ 2110 vacuum brake booster. Let's consider how to do this without difficulty and so that everything works as before.

It all starts with the removal of the vacuum brake booster VAZ 2110. To do this, unscrew all the screws, unfasten the belt that secures the expansion tank of the cooling system, remove it from its location by slightly lifting it. We put it carefully and fix it, then the left part of the soundproofing material is removed and set aside. The process is repeated with the right side as well.

After the procedure, the block with wires is disconnected from the cover of the brake reservoir, disconnect the hose from the vacuum brake booster check valve, unscrew the two nuts securing the main brake cylinder to the brake booster, then carefully move this cylinder to the side.

We move into the salon, unscrew the four nuts securing the amplifier bracket to the body, and also disconnect the wire blocks from the brake light switch. When everything is done, you can move again under the hood of the car and pull out the vacuum booster with the bracket.

We put or clamp the amplifier in a vice, pull out the small metal stopper with pliers, then knock out the stem by pressing on it from either side.

At the end, unscrew the two nuts that fasten the vacuum cleaner and the bracket, remove them, the process of removing this mechanism is completed. Installation is carried out in the reverse order, exactly up to each moment, for example, you do not need to put on the soundproofing material immediately, but first check its operation, only if there are no malfunctions, complete the installation of all components.

As you can see, with proper skill and following all the important steps, you can easily replace the vacuum amplifier with your own hands, without resorting to outside help and extra costs.

You can find a detailed video instruction for removing a vacuum cleaner on a VAZ 2110 here:

Outcome

The vacuum booster is an integral part of a modern car. It allows the driver to spend less effort on braking and improves the driving performance of the car. Repairing this unit seems very complicated, but with the proper skill and experience in repair work, as well as following the instructions exactly, you can replace the vacuum cleaner yourself without resorting to the services of craftsmen. However, this procedure is not for everyone, since the process of replacing the amplifier involves not only disassembly, but also assembly, which must also be carried out in accordance with all the rules. If you feel insecure in your own abilities or replacing the amplifier is difficult for you, then you should contact the experts. Also remember that at the slightest malfunction, this part needs to be repaired, because without proper high-quality brake work, your car is in potential danger, and with it your life.

It is in your power to ensure the long operation of the vacuum booster and make the car more manageable and comfortable.