Brake system of UAZ vehicles. Checking the vacuum booster, adjusting the brake pedal and the pressure regulator of the working brake system UAZ Hunter What makes the vacuum cleaner suitable for UAZ

VACUUM BRAKE BOOSTER OVERVIEW

MP-BS 3151-3510010

DESCRIPTION OF THE DEVICE AND OPERATING PRINCIPLE OF THE STANDARD CUT

Vacuum brake booster (VUT) is one of the most common devices, used in brake system modern car. VUT provides a reduction in the force applied to the brake pedal, while maintaining the efficiency of the working brake system.

Before proceeding to the description and review of the design of the VUT manufactured by MetalPart, we will briefly describe the principle of operation of this unit of the vehicle's brake system using the example of a standard vacuum brake booster.

The vacuum brake booster is sealed, made as a single unit with the main brake hydraulic cylinder located on it. VUT is located in engine compartment directly in front of the brake pedal.

Inside the amplifier housing are ( see fig.):

elastic diaphragm - the main working part of the device. The diaphragm divides the VUT body into two chambers. The first - vacuum, is directed towards the brake cylinder, the second, atmospheric - to the brake pedal. At the same time, the vacuum chamber communicates through a check valve with a source of vacuum. In the initial position, the pressure in the chambers is equally low.

- Master cylinder piston rod - passes through the diaphragm and is connected at one end to the brake pedal, and at the other - to the piston of the brake cylinder.

- Pusher- connected to the brake pedal.

- follower valve - blocks the channel connecting the atmospheric chamber with the vacuum one.

-return spring- puts the amplifier diaphragm in a standby state.

Rice. 1. The device of a regular VUT

The action of the VUT is based on the creation of a pressure difference in its chambers.

The depressed brake pedal transmits force through the pusher to the follower valve, which closes the channel between the atmospheric and vacuum chambers. The movement of the valve creates a communication of the atmospheric chamber with the atmosphere through the corresponding channel, as a result of which the vacuum in the chamber drops. Having overcome the resistance of the spring under the influence of the pressure difference, the diaphragm moves the piston rod of the brake cylinder.

In proportion to the force of pressing the brake pedal, an additional force appears on the piston rod of the master brake cylinder. The maximum additional force realized with the standard VUT is correlated with the force from the driver's leg with a coefficient equal to 3.5.

After the brake pedal is released, the atmospheric chamber is connected to the vacuum chamber, the pressure in the chambers equalizes. Under the action of the return spring, the diaphragm takes its original position, the device is again ready for operation. These, in general terms, are the device and principle of operation of a standard VUT.

TECHNICAL CHARACTERISTICS VUT MetalPart

ADVANTAGES AND DESIGN FEATURES VUT MetalPart

• gain 7,0 . The specified coefficient is achieved through the use of two vacuum chambers. VUT Metal Part provides effective braking with less effort on the brake pedal ;
• having two diaphragms. A longer service life of the VUT is provided - the load on each of the diaphragms is reduced. In case of failure of one of the VUT diaphragms Metal Part continues to work in the regular VUT mode, with a gain of 3.5;
• smaller dimensions compared to regular. Increased free engine compartment;
• check valve steel. Provides longer service life.

ANATOMY OF THE WUT Metal Part MP-BS3151-3510010

The vacuum brake booster is supplied in a three-layer corrugated cardboard package, which protects the product from mechanical damage during transportation.

To protect against corrosion, the VUT body is made of galvanized metal 2 mm thick and painted with powder enamel.

The tightness and strength of the device is ensured by the use of 16 stamping locks at the junction of the body with the cover. This type of connection eliminates the "leakage" of air and ensures the integrity of the VUT structure when exposed to vibration transmitted by the car body.

The photo below shows a rod pusher and a polyurethane foam filter seal. This filter element provides air purification and protects the atmospheric chamber from dust and moisture.

In a vacuum booster Metal Part a durable steel non-return valve is installed. The photo below shows a close-up of the check valve threads with traces of the compound used to seal the joint.

Shown below is a lock washer that secures the piston pusher collar in the seat.

Having dismantled the washer, we remove the pusher cuff.

Shown below is the mounting hole of the cuff with three working edges - they ensure the tightness of the vacuum chamber. This design solution eliminates the "leakage" of air into the vacuum chamber and ensures the stability of the VUT Metal Part at low revs engine.

Additional seal in the VUT cover provides a cuff with four working edges that protect the body of the servo valve from dust and moisture ingress.

To demonstrate the main design difference VUT Metal Part dismantle the housing cover. In a vacuum booster Metal Part situated three cameras - two vacuum and one atmospheric. The photo below shows the diaphragm separating the atmospheric and first vacuum chambers.

The use of two vacuum chambers and two diaphragms in the design of the VUT made it possible to double the total effective area of ​​the diaphragms, which led to an increase in the amplification factor of the VUT Metal Part up to value 7,0 .

In case of failure of one of the VUT diaphragms Metal Part continues to work in the regular mode, with a gain of 3.5.

This is how the cavity of the first vacuum chamber looks like:

To demonstrate the cavity of the second vacuum chamber, we dismantle the diaphragm separating the two vacuum chambers.

This review was prepared by engineers Metal Part to demonstrate the advantages of our company's vacuum booster.

Company Metal Part guarantees the high quality of its own products, as well as its long and flawless service, subject to the rules of installation and operation.

The hydraulic drive of brakes and clutches of automobiles contains a unit that facilitates the control of these systems - a vacuum booster. All about the brake and clutch vacuum boosters, their types and design, as well as the selection, repair and replacement of these units - read the article presented on the site.

Vacuum brake booster: stop the car effortlessly

Braking a car sometimes requires a lot of effort on the pedal, which leads to driver fatigue and carries a potential threat - at some point, the driver simply does not have enough strength for normal braking. A special unit solves all these problems - a vacuum brake booster. Read about what it is, about the operation of the amplifier and its operation in this article.

The main factor in the malfunction of the vacuum brake booster is its complete or partial inability to create a vacuum in the working chamber. A potential source of the problem is a broken or depressurized hose connection connecting the engine intake manifold and amplifier.

Interference in the operation of the unit is also caused by defects inside the amplifier - due to a violation of the integrity of the working surface of the diaphragm or loss of elasticity by the valve. In order to detect malfunctions of the vacuum brake booster, certain tests are carried out.

Methods and signs of detecting malfunctions of the vacuum brake booster

1. For example. Start the engine, and after a few minutes turn it off. Then press the brake pedal a few times with normal force. With a working amplifier at the moment of the first pressing, the pedal will be squeezed out, as expected, until it stops. The system will work, and the created vacuum will attract the diaphragm, which helps to push the piston of the brake master cylinder through the rod.

   Then the valve will equalize the pressure in the chamber with atmospheric. During the second and subsequent pressings of the pedal, there will be nowhere to take the vacuum from, which is why the pedal travel will become less and less. If there is no difference between the initial and subsequent pressings on the pedal, then it is clear: this device does not provide additional force in the master brake cylinder.

2. Following the experiment done, it is useful to perform one more. Engine off. The brake pedal has been pressed several times in a row. Her move indicated something. Either the results of the experiment seemed inconclusive, or there was a desire to make a control approbation. The following actions are performed. The brake pedal is depressed, and when the pedal is depressed, the engine starts.

   With a working vacuum booster, a vacuum is formed in its vacuum chamber, due to which the membrane presses on the rod, the rod pulls the pusher connected to the pedal, and the latter drops slightly.

   In the case when the pedal remained in place, it is concluded that the expected chain of events did not take place due to a malfunction of the vacuum brake booster. Such checks reveal significant damage to the part.

3. The next test makes it possible to determine the presence of small air leaks. With the car engine running, press the brake pedal, then, without releasing it, turn off the engine. Hold the pedal in the same position for half a minute.

   Due to the violation of the tightness of the amplifier, the pressure in the vacuum chamber will increase. The diaphragm, under the influence of the return spring, having lost the support of the force that balances its position, will press on the pusher and raise the brake pedal.

If this is not observed, then there are no malfunctions, and the vacuum brake booster is working normally. In any case, if it becomes necessary to repair any kind of brake assembly, it is taken into account that there may not be a second chance for repair, therefore, they turn to car service professionals for assistance in diagnosing and repairing. They can produce.

The effectiveness of the car's brakes is of great importance - if the brake system does not work effectively, an accident can occur. To keep the brakes clear, at all modern machines an amplifier is installed, it provides an instant stop vehicle when pressing the pedal.

Repair of the vacuum brake booster is necessary if the brakes become "cottony", and you have to press the pedal with great effort to brake.

Repair of the vacuum brake booster VAZ 2106, 2107, 2108, 2109, 2110

The vacuum brake booster (abbreviated as VUT) of VAZ vehicles facilitates the work of the driver - it enhances the effect of pressing the pedal in the brake system (TS). This assembly consists of the following main parts:

• valve;
• metal case;
• diaphragms;
• piston
• stock;
• powerful return spring;
• pusher, which is connected to the brake pedal;
• protective cover;
• flange for installing a non-return valve.

The body of the device is divided by a diaphragm into two halves, and from the side where the vacuum is created, the main brake cylinder is installed. A vacuum (vacuum) is created by connecting this part of the body to the intake manifold of the internal combustion engine, and when the engine is not running, the channel is blocked by a check valve installed in the VUT flange. Air (vacuum) with the help of a rod and a piston, when the brake is pressed, enhances the braking effect, thereby facilitating the work of the driver - there is no need to press the pedal with great force. After the pedal is released, a powerful return spring allows the diaphragm inside the body to return to its original position. When the engine is turned off, no vacuum is created in the system and the vacuum brake booster does not work.

On VAZ-2106-07 and VAZ-2108-10 cars, different appearance brake boosters, but the principle of operation of the devices is the same. We check the serviceability of the VUT as follows: we press the brake pedal and start the engine - if the pedal “falls through” (falls under foot pressure), the VUT works.

The main problem with the vacuum booster is damage to the diaphragm. When the diaphragm has ruptures, air penetrates from the outer part of the housing into the vacuum cavity, and no vacuum is created in the device. But not necessarily the malfunction may lie in the device itself - often the VUT does not work due to air leakage or for other reasons:

• defective check valve "vacuum";
• there is an air leak from the hose connecting the intake manifold to the brake booster;
• there is no compression in the ICE cylinder where the vacuum comes from.

It should be noted that the vacuum brake booster on VAZ 2106-10 vehicles is connected by a hose to the fourth engine cylinder.

Repair of the vacuum brake booster VAZ 2106, 2107, 2108, 2109, 2110 should begin with the dismantling of this unit, then the VUT must be disassembled.

VUT on a VAZ-classic car is removed quite simply, and if you have minimal locksmith skills, this work is not difficult to do. Remove the node as follows:

It is not difficult to disassemble the VUT 2108-2109, but for disassembly it is necessary to fix the device. We disassemble the node in the following order:

Usually, the repair kit for the VAZ-2109 vacuum booster has a diaphragm, a cuff, anther, covers (2 pcs.) And a valve. All the details should be changed so that later you do not have to redo the work. When assembling a vacuum booster, it is better to immediately fix the diaphragm on a plastic casing, so it will be easier to mount the assembly.

Which side the spring is placed on does not matter, but when assembling the amplifier, you will have to make an effort to get the holes in the housing onto the studs.

UAZ brake booster repair

Problems with the vacuum booster of UAZ vehicles can be identified by the following signs:

• the engine troit, and since on the "UAZ" engines the vacuum hose goes to the manifold of the first cylinder, if the VUT is faulty, this particular cylinder does not finish;
• a hiss is heard under the hood - the diaphragm poisons the air;
• pedal brakes hard, and is not pressed when starting the engine;
• there are wet smudges between the GTZ and the amplifier (brake fluid flows).

If smudges of “brakes” are found in the VUT area, it is urgent to change or repair the GTZ, but if the liquid has already entered the vacuum booster, it is likely that the VUT will also have to be repaired.

One more frequent malfunction in the brake system - failure of the check valve. This simple mechanism is very easy to check - you need to blow into it. The valve should be blown freely in one direction (when rarefied air is supplied from the manifold), and in reverse side air moves with great difficulty. If the valve is defective, it is blown freely in both directions.

The amplifier is removed on cars manufactured by the Ulyanovsk Automobile Plant according to the same principle as on VAZ cars. Consider the replacement of VUT using the example of a UAZ-31519 car:

the two lower nuts of the amplifier bracket are located in the passenger compartment, they are turnkey 17, we unscrew this fastener;

Features of the repair of UAZ vacuum boosters

Unlike the vacuum boosters of VAZ cars, on UAZ cars, the VUT body is very durable, and it is not at all easy to split it in half. You can bend the protrusions with a mount and a hammer, but this is how the work is done in violation of the technology - according to the instructions, one half must be rotated relative to the other. The biggest problem during disassembly is the "halfing" of the case - sometimes these parts boil so much that it is impossible to disassemble the assembly. Car owners advise not to press one body into another in any case - then turning will definitely not work.

Another problem in the repair of "vacuum trucks" is the low quality of spare parts in the repair kit, sometimes the installed parts are not enough for half a year. Motorists advise not to repair, but to buy a new spare part, although there is another minus here - VUT for cars like UAZ-469 or UAZ-452 is not cheap, about 3 thousand rubles. Alternatively, you can pick up a “vacuum” from a foreign car at a car disassembly, in which the main brake cylinder fits on the mounts, and install it on the car by fitting. As a result, it turns out cheaper and more reliable - imported parts, even in used condition, last for several years without any complaints.

Often, after replacing the VUT, problems appear, and the car no longer slows down as it was before with a working “vacuum” - the brake pedal takes at the very end, or the system is not completely released. The whole point here is the rod that presses the GTZ piston - it may not be adjusted from the factory. This stem has an adjusting screw, which is fixed with a lock nut. On UAZ vehicles (we do not take into account the Patriot model), we check the stem adjustment as follows:

More on UAZ Hunter the pedal can "take" at the very end, and it gets a lot of free play. It is necessary to pay attention to the position of the pedal - if it is too low from the floor in the cabin, it must be adjusted:

The vacuum booster is designed to create additional force applied to the rod of the master brake cylinder. The vacuum in the brake booster is created by reduced pressure in the intake manifold.

The vacuum booster cannot be repaired and is replaced in the event of a malfunction. If, with the engine running, an unusual amount of pedal force is required to achieve adequate braking, have the brake booster checked.

Check vacuum booster in the following order:

Depress the brake pedal 5-6 times when idle engine to create in the vacuum and atmospheric chambers of the vacuum amplifier the same pressure, close to atmospheric (remove the vacuum);

Keeping the brake pedal depressed, start the engine;

With a working vacuum booster, the brake pedal after starting the engine should “go forward” and weaken the resistance force on the leg;

If the brake pedal does not “go forward”, check the tightness of the connecting hose between the intake port and the booster or the vacuum booster itself.

The non-return valve may also be the cause of the malfunction of the vacuum booster. Using a screwdriver, carefully squeeze out the valve and blow it in the direction of the arrow stamped on the valve. The purge air must exit from the other side of the valve. If you blow against the arrow stamped on the valve, then the air, on the contrary, should not come out from the other side. During installation, the valve is pressed into the vacuum brake booster.

Removing and installing a vacuum booster without an installed ABS system

Withdrawal- the vacuum booster is carried out in the following order:

Remove the "-" wire from the AB output;

Remove the soundproofing located in engine compartment engine;

Remove AB;

Remove expansion tank cooling systems;

Disconnect the multi-pin connector for indicating the temperature of the coolant and unscrew the two bolts;

Unscrew two bolts and remove the right partition of the AB compartment;

Turn away one bolt and remove the left back partition of compartment AB. Set the expansion tank aside;

Disconnect the connector on the brake fluid reservoir cap and unscrew the reservoir cap;

Using a siphon-pear, pump out brake fluid from the tank and remove the master brake cylinder;

Disconnect the vacuum hose going to the vacuum brake booster;

Remove the lower casing of the panel of devices from outside the driver;