Working brake system
Brake working mechanisms are placed in the wheels of the car, so they are called wheeled. There are mechanical, hydraulic and pneumatic drive of brake mechanisms.
In the device hydraulic driveuse properties of liquids (Pascal law)
Fig. The diagram of the hydraulic brake drive A is the location, b - compound, B - the effect of the brakes. 1 - main brake cylinder, 2 - pipelines, 3 - brake cylinders of wheels, 4 - brake pedal, 5 - plugging of hoses, 6 - housing of the main brake cylinder, 7 - flexible hoses, 8 - tank for brake fluid, 9 - block 10 - Brake drum.
The hydraulic drive consists of the main brake cylinder 1C with a brake fluid reservoir connected by pipelines 2 with brake cylinders of 3 wheels, hoses, hydraulic amplifier.
The entire system is filled with a special brake fluid without corrosive car rubber parts.
The fluid in the hydraulic brake system is supplied from the head cylinder 1 to the cylinders of 3 wheels over metal tubes 2 and special hoses made of rubberized tissue 7, withstanding high pressure and oil action. This design allows you to control brakes, despite the vibrations of bridges and wheels.
Main brake cylinder.
The main brake cylinder is connected to wheel cylinders using a pipeline system consisting of metal tubes, tees, fittings and flexible hoses from rubberized tissue.
Fig. Main Brake Cylinder Car Gas 1 - Cover, 2 - Replenishing Tank, 3 - Nutrition Fitting, 4 and 17 - Cases, 5 - Protective Cap, 6 - Pusher, 7 and 15 - Pistons, 8 - Thrust Bolt, 9 - Head Sealing Ring , 10 - Cuffs, 11, 16 - Piston Heads, 12 - Strong Rod, 13 - Returning Spring, 14 - Personal Piston Explosion, 18 - Forest Piston Explorer, 19 - Excessive Pressure Valve, A - Liquid Release Fitting In the Rear Brake Drive Wheels, b - fluid exit fitting in the contour of the front wheel brake drive, I and II - cylinder cavity.
The main brake cylinder creates a pressure in two independent hydraulic brake drive circuits, a piston 7 in the rear wheel drive, and the piston 15 in the drive of the front wheels. If one of the contours is unloaded and stops slowing down the wheels associated with it, the other will continue to work. At the same time, the driver will continue to stop the vehicle, though with less efficiency.
The pistons are placed in the cylinders 4 and 17, the housings of which are connected by the feeding fittings 3 with a replenishing tank, and the output of fittings A and B - with the contours of the brake actuator, respectively, the rear and front wheels.
The role of the bypass valve is performed by floating heads 11 installed on the pistons. In the deficited position between the head and the piston under the action of return springs, the gap is set. The cavities of the I and II of the cylinder are communicated with the tank 2. When you press the brake pedal, I move the rear wheel brake drive piston, and then with a stop rod 12 moves the front wheels actuator and the brake fluid is injected via the valve 19 in the working brake cylinders of the wheels. Under the action of the springs of the head 11 pistons pressed against their end, the discharge of cavities I and II with a tank and a pressure is created in the braking actuator. With the help of valves 19 in the brake system, the overpressure of the brake fluid is maintained 40 - 80 kPa. After stopping the pressed pedal, the piston returns to the starting position of the spring 13.
Under the hood of the car there is a spare tank 2 made from transparent material, which allows you to control the level of fluid in it. The replenishing tank serves to power the brake system. The cylinder and the tank are connected by holes through which the liquid flows from the tank into the cylinder and back.
The fluid level should always be at a distance of 15 - 20 mm from the edge of the filling hole.
The tank has three isolated sections, one of which feeds the clutch drive system, and the other two is a system of separate brake drive.
On cars there is a double-circuit braking drive with separate braking of the front and rear wheels, which has a hydraulic amplifier and a vacuum balloon with a lock valve that provide independent power of each contour. The hydraulic amplifier is used to reduce the driver's effort pushing to the brake pedal using a vacuum arising in the engine suction pipeline.
Hydraulic amplifierit consists of a housing (power chamber), a hydraulic cylinder 9 and a control valve. In the case of the power chamber, a diaphragm with a thrust plate, a spring and a pusher are installed. The pusher is connected with one end with a dish of a diaphragm, and on the other with the piston of the amplifier cylinder in which the ball valve is installed. The power chamber is separated by a movable diaphragm into two parts, interconnected by the homutics.
One part is associated with the atmosphere, and the other with an exhaust manifold of the engine. The hydraulic amplifier works as follows when the brake pedal is released, the control valve is closed, and the vacuum is open, and through it both chamber cavities communicate with each other.
When you press the brake pedal 1, the driver is forced to move the aperture, the ball valve of the amplifier piston 10 opens, and the liquid from the main brake cylinder enters the wheel brakes, leading them into action and creating an additional force on the principle of the main brake cylinder, acting in the same direction where Moves the rod of the driver's foot. As a result, to achieve the necessary braking efficiency, press the brake pedal with less effort.
The vacuum amplifier of the working brake system is valid only when the engine is running. This must be taken into account when moving a vehicle with a non-working engine (for example, when towing a faulty vehicle). In the latter case, to reduce the speed or stop the car, the brake pedal will have to be pressed with a large force than on a vehicle with a working amplifier.
Pneumatic brake system. The work of the pneumatic brake system:the compressor creates a supply of air under pressure, which is stored in air cylinders. When the brake pedal is pressed on the brake valve, which creates pressure in the brake chambers, which are powered by a brake mechanism lever, which produces braking and braking stops when the pedal is elected.
Pneumatic acceptance applied on heavy cargo cars. It allows to obtain quite large forces in brake mechanisms with small forces applied by the driver to the brake pedal.
Fig. Scheme of a pneumatic drive of car brakes ZIL. 1 - Compressor, 2 - pressure gauge, 3 - air cylinders, 4 - rear brake chambers, 5 - connecting head, 6 - dismissal crane, 7 - connecting hose, 8 - brake valve, 9 - front brake chambers.
The car's pneumatic drive includes a compressor 1, pumping compressed air to cylinders (receivers) 3, brake chambers 4 and 9, brake valve 8, associated with the brake pedal and the connecting head 5 with a dismissal crane 6, allowing you to connect the trailer system to the pneumatic brake system Driving brakes of a car - tractor.
The compressor shaft is driven by the crankshaft of the engine belt transmission. The pressure created by the compressor is automatically limited to the pressure regulator. The pressure is controlled by a pressure gauge.
When you click on the brake pedal, the brake crane reports brake chambersall wheels with receiver. Brake cameracars the brake mechanism due to the energy of compressed air. Entering compressed air into each chamber, which beats the diaphragm to the body along with the disk and moves the rod.
Fig. Brake Camera 1 - Case Cover, 2 - Fitting for Supply and Offering Air, 3 - Diaphragm, 4 - Housing, 5 - Skot, 6 - Lever, 7 - Worm, 8 - Wrist Cutter, 9 - Worm gear, 10 - Farm Sign Brake fist, 11 - diaphragm springs.
The rod turns the lever 6, and with it and the shaft 10 of the expansion fist of the brake mechanism of the wheel, pressing the block to the brake drum. After the brake pedal is released, the pads return to its original position, the brake valve 8 dismisses the brake chambers with receivers and connects them to the atmosphere. Air from the chambers comes out, the springs 11 return the diaphragm in the original position and the braking stops. The worm of the worm 7 mounted in the lever 6 and the worm gear 9 allow you to rotate the shaft 10 relative to the lever and to adjust the gap between the pads and the brake drum. Compressorit is a source of compressed air that feeds all the units of the pneumatic system. On trucks and buses use single-stage double-cylinder compressors of one-way action . The compressor pumps air into air cylinders.
Fig. Compressor scheme. 1 - Piston, 2 - Purchasing Valve, 3 - Air Power Supplies in Air Cylinder, 4 - Inlet Valve, 5 - Air Body Air Filter, 6 - Adjustable Cap, 7 - Stone, 8 - Ball Valve Block, 9 - Air Pipe Ballery, 10 - discharge channel, 11 - plunger of the unloading device, and - block of cylinders, b - pressure regulator, B - hole.
When the piston is down, a vacuum is created in the compressor cylinder, the inlet valve opens and air flows through the air filter. During the course of the piston, the intake valve closes, compressed air through the open injection valve 2, enters through the pipelines to the head and air cylinders.
Pressure regulator B.supports the predetermined air pressure in the pneumatic system automatically. The design of the regulator includes a housing and a block of eight ball valves. With a pressure in the system below 0.6 MPa, the ball valves are omitted and the lower ball closes the hole communicating with air ballons. Through the inclined channels of the fitting and the hole in the unloading device, air from the atmosphere is falling.
Ball valves rise when the pressure in the system reaches 0.75 mp, the upper ball will close the inclined channel of the fitting, bumping air from the atmosphere, air from cylinders begins to the discharge device. Compressed air turns off the compressor intake valves from work. The upper valve opens at a pressure of 0.75 mp, and the lower at a pressure of less than 0, 6 MPa.
Adjustable cap 6 can be adjusted to the springs tightening and set the pressure at which the compressor will turn off.
Aerial cylindersneed to storage compressed air. On cylinders there are a crane for condensate drain, and on the right cylinder air selection faucet. The volume of air cylinders is enough to 10 braking.
To eliminate the pressure in the system of pneumatic brakes, with a faulty pressure regulator, a safety valve is installed on the air cylinder, which opens if the pressure in the system exceeds 0.95 MPa.
Fig. Oco oil separator.
Ocliding separator- It is installed in front of the cylinders and is intended for cleaning compressed air from the compressor from oil and moisture. The oil has a harmful effect on the rubber parts of the pneumatic system, and the water pairs condensing in the nodes of the system at negative temperatures freeze, which leads to a violation of the main elements of the car's pneumatic system.
In the housing 1, the check valve 2 is installed, pressed to the spring socket 3. From above, the housing is closed with a plug 4. To seal the case and glass 7, a rubber ring 8 is installed (the seal occurs when the conical tip of the tip 6 is tightened). The air from the compressor enters the hole A, passes through the brass grid of the element 5, separated from the oil and moisture, enters the rod hole, and, pressing the check valve, goes into the pipeline associated with the cylinder.
The oil and moisture remaining on the grid flow into the glass 7. For the release of condensate, a drain crane is installed at the bottom of the glass.
Fig. Drain crane
Drain cranes are designed for periodic condensate drain from all cylinders and an oil separator. The condensate release is carried out by the tilt of the valve 3 using the ring 5. Spring 2 presses the valve to the saddle 4 in the normal state. With the help of fitting 1, the faucet is screwed into the balloon.
To increase the reliability of the pneumatic system and the exclusion of condensate freezing, an antifreeze pump is used, which is installed between the oil separator and the pressure regulator. It serves to serve in a pneumatic portion of the frost-resistant fluid, which is located in a special tank.
Antifreeze pumpmust work only during the cold season. In the warm time it is removed. It is filled with a mixture of ethyl (300 cm3) and isoamyl (2 cm3) of alcohols.
Unloading device. It works from the pressure regulator and is located in the compressor cylinder block. When the compressed air pressure in the system reaches 0.75 MPa, the pressure regulator B. Air flow into the brake system is stopped, as the inlet valves are opening 4 of both cylinders under the action of air from the cylinder through the pipeline to the discharge channel and raise plungers, which in turn Open valves.
When a pressure decreases, the return process takes place. Plungers are lowered and unloading device ceases to valves.
Compressed air enters the cylinders, until the pressure in them reach 0.75 MPa.
The cylinder block and the head head during operation is cooled by a liquid coming from the cooling system into the water jacket of the compressor cylinder block. Oilly oil, which lubricates the components of the compressor.
Brake crane. The brake valve is designed to control the wheel brakes of the car and trailer. The brake valve serves to control the car brakes as a result of adjusting the supply of compressed air from cylinders to the brake chambers.Fig. Brake Crane Car Zil
1 - Housing of levers, 2 - double lever, 3 - bolt, 4 - cam, 5 - traction, 6 - delaying, 7 - stock section of trailer braking, 8 - diaphragm, 9 and 12 - valve saddles, 10 - inlet valve, 11 - the exhaust valve, 13 is the stop signal switch, 14 is a stop signal diaphragm, 15-rod of the car braking section, 16 is the brake crane case.
The brake valve provides a constant braking force with the constant position of the brake pedal and rapidly disbuilt when the pedal is stopped.
The body of the brake crane is divided into two sections - the bottom controls the brakes of the car, and the upper trailer brakes. In each section, a diaphragm of rubberized tissue with a slot of the convex valve is fixed between the lid and the housing. The sections cover are equipped with double valves located on one straighten and having a common spring. In the brake crane case there are two rods with springs 7 and 15.
The housing of the levers is attached to the brake crane body, in which, in turn, there are a double lever 2 and the thrust 5. The double lever consists of two half, interconnected by the movable axis.
If you press the brake pedal, then the thrust5 is mixed to the left, fascinating the upper lever 2, moves the rod 7 of the upper section to the left. When the upper rod 7 flies into the restrictive bolt 3, the lower end of the top half of the lever removes the lower half of the lever to the right along with the bottom section. The trailer brakes are turned on slightly earlier than the car brakes, which eliminates the collision of the trailer with the car.
Fig. Schemes of brakes: A - when disgraced, b - when braking. 1 - Compressor, 2 - Brake Crane, 3 and 13 - Exhaust Valves, 4 and 5 - Inlet Valves, 6 - Disobedient Crane, 7 - Air distributor, 8 - Air balloon, 9 - Trailer wheel brake chamber, 10 - Air balloon , 11 - Brake chamber of the car wheel, 12 - inlet valve spring, 14 - traction.
the upper section is open in a deficer state, and compressed air from cylinders passes into the air distributor and charges the trailer balloon.
The exhaust valve 3 is open and reports the brake chambers of the car with the atmosphere, with the intake valve 4 closed.
When the brake pedal is pressed, the thrust 14 moves to the left with the rod and the top end of the lever 2, having removed the valve seat 13. Under the action of the spring 12, the inlet valve of the upper section is closed, and the outlet opens. The compressed air from the cylinder of the trailer enters the brake chambers 9, and the air from the air distributor enters the atmosphere. The trailer wheels will be inhibited.
Brake in the parking lot is carried out by the mechanism of manual drive brakes, connected to the central brake of the car.
Manometerallows you to check the air pressure in both air cylinders and in the brake chambers of the pneumatic drive system. For this, it has two arrows and two scales. On the bottom scale checks the pressure in the brake chambers, along the top - in air cylinders.
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It is necessary to quickly change the speed or complete stopping of the car and hold it in place when parking.
To do this, there are such types of brake systems such as working, parking, spare and auxiliary system (retarder brake).
Working brake system
It is always used at any vehicle speed for a complete stop or to reduce speed. The working brake system begins to work when the brake pedal is pressed. This system is the most effective when compared with other species.Spare brake system
It is used for malfunction of the main system. The spare brake system is in the form of an autonomous system or its function performs part of a working brake system.Parking brake system
It is necessary to hold the car a certain time in one place. The parking system completely eliminates the movement of the car spontaneously.Auxiliary brake system
Used on vehicles with increased weight. Auxiliary system is used to brake on descents. It often happens that on cars the role of the auxiliary system performs the engine, where the exhaust pipe is overlapped with a damper.The brake system is an important car to ensure active safety. Different systems and devices are used on cars that increase the efficiency of the system when braking is an anti-lock system, emergency braking amplifier, brake amplifier.
The brake system includes brake drive and brake mechanism.
Brake hydraulic diagram:
1 - Contour Pipeline "Left Front-Right Rear Brake"; 2-signal device; 3 - Contour Pipeline "Right Front - Left Rear Brake"; 4 - the main cylinder tank; 5 is the main cylinder of hydraulic brakes; 6 - vacuum amplifier; 7 - brake pedal; 8 - rear brake pressure regulator; 9 - parking brake cable; 10 - brake mechanism rear wheel; 11 - the adjusting tip of the parking brake; 12 - parking brake drive lever; 13 - Brake mechanism of the front wheel.
Brake mechanism
Blocks the rotation of the wheels and as a result, the appearance of the brake force, which stops the vehicle. Brake mechanisms are located on the rear and front wheels.In theory - all brake mechanisms are logical to call the brakes. And already in turn, they can be divided by friction - disk and drums. The brake mechanisms of the main system are mounted in the wheel, and the mechanism of the parking system is behind the transfer box or gearbox.
About drum and disc brake mechanisms
The brake mechanism usually consists of two parts, from rotating and fixed. The rotating part of the drum mechanism is the brake drum, and the fixed part is the brake pads.
Drum brake mechanisms
Usually stand on the rear wheels. In the process of wear, the clearance between the drum and the block increases and there are mechanical regulators to eliminate it.
Drum Brake Rear Wheel Mechanism:
1 - cup; 2 - clamping spring; 3 - drive lever; 4 - brake shoe; 5 - upper blast spring; 6 - spacer plank; 7 - adjusting wedge; 8 - wheel brake cylinder; 9 - brake shield; 10 - bolt; 11 - rod; 12 - eccentric; 13 - Purpose Spring; 14 - lower chamber spring; 15 - clamping spring space plank.
On cars, brake mechanisms may have different combinations:
- two disk front, two drum rear;
- four disk;
- four drums.
In the brake disk mechanism
- The disk rotates, and the two pads stand motionless, they are installed inside the caliper. The caliper is working cylinders, they press brake pads when braking, and the caliper itself is well fixed on the bracket. To improve heat removal from the working area, ventilated discs are often used.
Disc brake diagram:
1 - wheel heap; 2 - guide finger; 3 - viewing hole; 4 - caliper; 5 - valve; 6 - work cylinder; 7 - brake hose; 8 - brake shoe; 9 - ventilation hole; 10 - brake disc; 11 - wheel hub; 12 - Miscoring cap.
About brake drives
In automotive brake systems, these types of brake drives have been applied:
- hydraulic;
- pneumatic;
- combined.
- mechanical;
Hydraulic drive
Received the widespread car in the working brake system. It includes:- main brake cylinder;
- brake pedal;
- wheeled cylinders;
- brake amplifier
- hoses and pipelines (work circuit).
With an effort on the brake pedal, the driver passes an effort from foot to the main brake cylinder. The brake amplifier additionally creates an effort, thereby facilitating the life of the driver. A wide application of machines purchased a vacuum brake amplifier.
The main brake cylinder pumps the brake fluid to the brake cylinders. Usually above the main cylinder there is an expansion tank, it contains brake fluid.
The wheeled cylinder presses the brake pads to the brake drum or disk.
The working circuit is now maintaining the main and auxiliary. For example, the whole system is properly, it means both, but when one of them is malfunction - the other will work.
Three main layouts of the separation of work circuits are widespread:
- 2 + 2 connected parallel - rear + front;
- 2 + 2 connected diagonal - right front + left rear and so on;
- 4 + 2 into one circuit two fronts are connected, and in other brake mechanisms of all wheels.
Layout layout diagram:
1 - main brake cylinder with a vacuum amplifier; 2 - fluid pressure regulator in the rear brake mechanisms; 3-4 - work circuits.
Progress does not stand still and now different electronic components are added to the hydraulic brake drive:
- emergency braking amplifier
- anti-lock brake system;
- anti-pass system;
- brake force distribution system;
- electronic blocking of differential.
Pneumatic drive It is used in the brake system of heavy vehicles.
Combined brake drive - This is a combination of different types of drive.
Mechanical drive It is used in the parking brake system. It includes a system of thrust and cables, which combines the system into one unit, usually on the rear wheels has a drive. The brake lever is connected using a thin cable with brake mechanisms, where there is a device that drives basic or parking pads.
There are cars where the parking system works from a foot pedal. Now they have become increasingly used in the parking system the electric drive, which was called - electromechanical parking brake .
So, how the hydraulic brake system works
It remains to consider the operation of the brake system, which we will do on the example of the hydraulic system.
When the driver presses the brake pedal, the load is transmitted to the amplifier and it creates an effort on the main brake cylinder. And in turn, the piston through the pipelines is injected into the wheeled cylinders. Pistons of wheel cylinders from fluid pressure move brake pads to disks or drums and braking vehicles.
When the driver removes his leg with brake pedal, the pedal from the return spring returns to the initial position. Also, the piston of the main brake cylinder is returned to its position, and the springs are removed from the drums or disks.
To date, the design of the brake systems of most passenger cars is about the same. The brake system of the car consists of three types:
Basic (Working) - serves to slow down the vehicle and to stop it.
Auxiliary (Emergency) - a spare brake system required to stop the car at the failure of the main brake system.
Parking - The brake system that fixes the car during the parking lot and keeps it on the slopes, but may also be part of the emergency system.
Car brake system elements
If we talk about the components, the brake system can be divided into three groups of elements:
- brake drive (brake pedal; brake vacuum amplifier; main brake cylinder; wheel brake cylinders; pressure regulator, hoses and pipelines);
- brake mechanisms (brake drum or disc, as well as brake pads);
- components of auxiliary electronics (ABS, EBD, etc.).
Brake system
The process of operation of the brake system in most passenger cars is as follows: the driver presses the brake pedal, which, in turn, transmits an effort to the main brake cylinder through a vacuum brake amplifier.
Next, the main brake cylinder creates the pressure of the brake fluid, the injector of it along the contour to the brake cylinders (the system of two independent contours is almost always used in modern cars: if one refuses, the second will allow the car to stop).
The wheel cylinders are then actuating the brake mechanisms: in each of them inside the caliper (if it comes to disk brakes), brake pads are installed, which, pressed against rotating brake discs, slow down the rotation.
To enhance security In addition to the above-described scheme, automakers began to establish auxiliary electronic systems that can increase the efficiency and safety of braking. The most popular of them are an anti-lock system (Anti-Lock Braking System, ABS) and a brake force distribution system (ELECTRONIC BRAKEFORCE DISTRIBUTION, EBD). If ABS prevents the wheel lock during emergency braking, the EBD is prevalent: the control electronics uses ABS sensors, analyzes the rotation of each wheel (as well as the angle of rotation of the front wheels) when braking and individually dispensing the braking force on it.
All this allows the car to maintain a course stability, and also reduces the likelihood of its drift or demolition when braking in turn or on a mixed coating.
Diagnostics and malfunction of the brake system
The complication of the design of the brake systems led both to a more extensive list of possible breakdowns, and to more complex diagnostics. Despite this, many malfunctions can be diagnosed independently, which will allow you to eliminate problems at an early stage. Next we give signs of faults and the most frequent causes of their occurrence.
1) Reducing the efficiency of the system as a whole:
Strong wear of brake discs and / or brake pads (late maintenance).
Reducing the friction properties of the brake pads (overheating of the brake mechanisms, the use of low-quality spare parts, etc.).
Wear wheel or main brake cylinders.
The failure of the vacuum brake amplifier.
Pressure in tires not provided for by the manufacturer of the car.
Installation of wheels, the size of which is not provided for by the manufacturer of the car.
2) Falling the brake pedal (or too "soft" brake pedal):
- "Recent" in the contours of the brake system.
The leakage of the brake fluid and as a result, serious problems with the car, up to the complete brake failure. It may be caused by the failure of one of the brake contours.
Boiling brake fluid (poor-quality liquid or non-compliance with the timing of its replacement).
Malfunction of the main brake cylinder.
Malfunction of workers (wheeled) brake cylinders.
3) Too "tight" brake pedal:
Vacuum amplifier breakdown or damage to its hoses.
Wearing elements of brake cylinders.
4) car care to the side when braking:
Uneven wear of brake pads and / or brake discs (incorrect installation of elements; damage to the caliper; brake cylinder breakage; damage to the surface of the brake disc).
Malfunction or increased wear of one or more brake wheels (poor-quality brake fluid, poor-quality components or just natural wear of parts).
Failure to one of the brake contours (damage to the tightness of the brake tubes and hoses).
Uneven wear of tires. Most often it is caused by violation Installation angles of wheels (score-collapse) of the car.
Uneven pressure in the front and / or in the rear wheels.
5) Vibration when braking:
Damage to brake discs. Often caused by their overheating, for example, with emergency braking at high speed.
Damage to the wheelbar or tire.
Incorrect wheel balancing.
6) Foreign noise when braking (can be expressed by a grinding or creak of brake mechanisms):
Wear pads before performing special indicator plates. Indicates the need to replace the pads.
Full wear of the friction pads of the brake pads. May be accompanied by the vibration of the steering wheel and the brake pedal.
Overheating brake pads or dirt and sand in them.
The use of low-quality or fake brake pads.
Offset caliper or insufficient lubrication of pins. Installing anti-graded plates or cleaning and lubrication of brake calipers is necessary.
7) Lamp "ABS" is burning:
Fault or clogging ABS sensors.
The failure of the block (modulator) ABS.
Open or bad contact in cable connection.
The fuse of the ABS system burned down.
8) BRAKE lamp is burning:
Tighten the hand brake.
Low brake fluid.
Malfunction of the brake fluid sensor.
Bad contact or broken joints of the manual brake lever.
Worn brake pads.
The ABS system is faulty (see paragraph 7).
Periodicity of replacement of pads and brake discs
In all listed cases, it is necessary but best - not to allow critical wear of the details. For example, the difference in the thickness of the new and worn brake disc should not exceed 2-3 mm, and the residual thickness of the material of the pad must be at least 2 mm.
It is not recommended to be guided by car mileage when replacing brake elements is not recommended: in the conditions of urban ride, for example, the front pads can be wary in 10 thousand km, while in country trips can withstand 50-60 thousand km (rear pads, as a rule , wears an average of 2-3 times slower than the front).
It is possible to estimate the status of the brake elements, and without removing the wheels from the car: there should be no deep duct on the disk, and the metal part of the block should not be adjusted close to the brake disc.
Prevention of the brake system:
- Contact specialized service centers.
- On time change the brake fluid: manufacturers are recommended to conduct this procedure every 30-40 thousand mileage kilometers or every two years.
- New discs and pads need to run through: throughout the first kilometers after replacing parts, avoid intensive and long-term braking.
- Do not ignore the mobility of the car on-board computer: modern cars can warn about the need to visit the service.
- Use high-quality components that meet the requirements of the car manufacturer.
- When replacing the pads, it is recommended to use lubricant for calipers and clean them from dirt.
- Watch out for the condition of the car's wheels and do not use tires and discs whose parameters differ from the manufacturer recommended by the manufacturer.
To effectively control the movement of any mechanical means - adjusting the speed on one or another section of the path, slowing it when performing maneuvers, finally, to stop in the right place - and including emergency - on all cargo and passenger cars, the corresponding brake machine must be installed on all cargo and passenger cars system. To hold the machine on site during a long parking, especially on the slope, a parking brake is provided.
For the safe operation of the vehicle, this system should be reliable as no other. It is not by chance that in the list of faults under which the use of the vehicle is prohibited (annex to the RF traffic rules), brake system malfunctions are made to first place.
Classification of car brake systems
Three or four types of brake systems are installed on modern cars:
- working;
- parking;
- auxiliary;
- spare.
The main and most effective brake system of the car is working. It is used at all movement time to regulate speed and complete stop. Its device is pretty simple. It is driven by pressing the brake pedal with the right foot of the driver. Such an order provides simultaneous discharge of engine speed, due to the removal of the leg with the accelerator pedal, and braking. 
The parking brake system, as follows from the title, is designed to ensure the immobility of the vehicle during a long parking lot. In practice, experienced drivers leave the machine with the first or rear handle. However, on large slopes it may not be enough.
Manual parking brakes are also used when starting from the scene on uneven areas of the road, when the right leg should be on the gas pedal, and the left squeezes the clutch. Smoothly releasing the brake lever, including simultaneously grip and adding gas, it is possible to prevent arbitrary car rolling under the slope.
A spare brake system is designed to duplicate the main working in the event of its failure. This can be a fully autonomous device, or represent a part one of the brake drive circuits. Alternatively, the spare system can perform a parking system.
Auxiliary brake system is installed on heavy vehicles, for example, on domestic kamahas, masses, cruises. It is designed to reduce the load on the main working system during long-term braking - when driving in the mountains or by hilly terrain.
Device system and principle of operation
The main in the brake system of any car is brake mechanisms and their drives. Hydraulic brake drive used on passenger cars consists of: 
- pedals in the cabin;
- working brake cylinders of the front and rear wheels;
- pipeline (brake pipes);
- the main brake cylinder with a tank.
The principle of operation is such - the driver presses the brake pedal, leading the piston of the main brake cylinder. The piston squeezes the liquid into pipelines to the brake mechanisms that in one way or another create resistance to the rotation of the wheels, and thus braking occurs.
The brake pedal released by returning the spring returns the piston backwards, and the liquid flows back to the main cylinder - wheels are disengaged.
On domestic rear-wheel drive vehicles, the brake system scheme provides a separate supply of fluid from the main cylinder to the front and rear wheels.
On foreign cars and front-wheel drive vases, the circuit of the contour of the "Left Front-Right Rear" pipeline and "Right Front - left back" is used.
Types of brake mechanisms used in cars
On the overwhelming majority of the car, friction-type brake mechanisms operating on the principle of friction forces are installed. They are installed directly in the wheel and are structurally divided into: 
- drum;
- disk.
There was a tradition to install drum mechanisms on the rear wheels, and disk to the front. Today, depending on the model, the same types can be put on all four wheels - or drum, or disk.
Device and operation of drum brake mechanism
The drum type system (drum mechanism) consists of two blocks, a brake cylinder and a coupling spring placed on a shield inside the brake drum. Friction lining closed or glued on the pads.
The brake pads are hinged with their lower ends on the supports, and the upper - under the influence of a coupling spring - rest in the pistons of the wheel cylinder. In the uneasured position between the pads and the drum there is a gap, providing free rotation of the wheel. 
When liquid flows into the cylinder through the brake tube to the cylinder, pistons, disperse, push the pads. They come to a dense contact with the brake drum rotating on the hub, and the friction force causes braking the wheels.
It should be noted that in the presented design of the front and rear pads occurs unevenly. The fact is that the friction pads of the front in the course of the movement of the pad at the time of braking when moving forward are pressed against the drum always with greater force than the rear. As an output, it is recommended to change blocks by places after a certain period.
Brake mechanism of disk type
The device of disk brakes consists of:
- the caliper attached to the suspension in the body of which is placed outdoor and internal brake cylinders (maybe one) and two brake pads;
- disk, which is fixed on the wheel hub.
When braking the pistons of working cylinders with the help of hydraulics, brake pads are pressed to the rotating disk, stopping the latter.
Comparative characteristics
Drum brakes are easier and cheaper in production. They have a property called - the effect of mechanical self-esteem. That is, with prolonged pressure, the pedal has repeatedly increasing the footing effect. This happens due to the fact that the pads are connected with the lower parts, and the friction of the front of the drum enhances the pressure onto the rear pad.
However, the mechanism of disk brakes is less and easier. Temperature resistance is higher, they are faster and better cooled due to the provided windows-windows. And replacing worn disk pads is much easier than drums, which is important if repairs independently.
Principle of operation of the parking brake
It is a purely mechanical device. It is activated by raising the "handler" lever to the vertical position until the click is clicking. At the same time, there are tension of two metal cables, passing under the bottom of the car, which tightly press the brake pads of the rear wheels to the drums.
To remove the car from the parking brake, you need to drown a finger to the locking button and omit the lever on the book, in the original position.
Do not forget to check the position of the handbrake before starting the movement! Riding with a manual brake, brake pads will quickly dissect.
Car Brake System Care
As one of the most important nodes, the brake system of the car requires constant attention and care. Here, literally any malfunction can lead to unpredictable consequences on the road.
Some diagnoses can be put on the basis of the nature of the behavior of the brake pedal. So the enlarged course or the "soft" pedal indicate, most likely, on air entering the hydraulic system as a result of the leakage of the brake fluid. Therefore, it is necessary to periodically monitor the fluid level in the tank.
Its increased consumption may be a consequence of damage to the hydrogen and tubes, as well as ordinary evaporation over time. This leads to an ingress of the air and brake failure.
The details that have come into disrepair must be replaced, and the system will have to pump, releasing air from each working cylinder on wheels and topping the liquid. The process is long and tedious.
Care of the car when braking aside speaks of a possible way out of order of one of the working cylinders or excessive wear of the lining on a particular wheel. When contamination of the brake mechanisms, characteristic noise may occur when you press the pedal.
All of these faults are easily eliminated independently or by contacting the service center. And in order to minimize the above-described troubles, take care of the brakes, often use the engine braking, especially on steep and protracted descents. A long time to turn on the main working system leads to overheating of parts and serves as the cause of various breakdowns.
Passenger car. You will also learn how to produce system pumping correctly. Constructions with anti-locking system will be considered. At the moment, no qualitative car do without them. Of course, we are talking about the machines of the average price category and above. Budget cars can be equipped with this design, but it goes as an additional option. In general, the brake systems of all machines are the same, they consist of identical elements.
A little theory about the brake system
As you understand, it is necessary in order to change the speed of the car. The signal to this can serve as a driver, or an electronic control system. It is also necessary to keep the car motionless during parking.
Three types of brake systems are distinguished. The first is, of course, working. It is necessary for normal operation of the machine. With it, braking from large or low speeds is carried out. What features is the "Niva-2121" braking system, the scheme of which is classical, will be discussed below.
The second type is parking. It is more known as a handbrake, if you need to put the car for a long time. In particular, if there is a slope of the road surface, this system is simply necessary. The handbrake can be used during an emergency stop. And there are still systems of the spare type. They relatively recently began to be used on cars. Most often, they can be found on those machines on which there is an electric handbrake. Its main purpose - to give the driver to stop the car if the working system refuses. It is mounted on machines with an electric manual brake for one reason: the parking brake cannot be squeezed if the vehicle speed is greater than zero.
Principle of operation
We are accustomed that when you click on the brake pedal, the car starts to slow down. But not everyone goes into the details of what processes occur. Not everyone knows how the VAZ-2109 brake system works, the diagram of which is given in this article. If it is easier to say, then the stop of the car occurs only by compressing the liquid in the tubes and hoses. Pressure is created using the main brake cylinder, it is the main node of the system.
Everyone used to see hydraulic brakes, but there are structures that use no fluid pressure, but compressed air. They are identical with hydraulic, only reliability they turn out to be much higher. The elements used in pneumatic brakes must withstand a very large pressure. True, it is comparable to the one that is in the hydraulic drive. It is only necessary to implement the receiver for storing compressed air. There are also electromechanical brakes. They are driven by electric motors and special cables.
