For effective control of the movement of any mechanical means - speed control on a particular section of the track, slowing it down when performing maneuvers, and finally, to stop in the right place - including emergency - all trucks and cars must be equipped with a brake corresponding to the class of the vehicle. system. To hold the machine in place during long periods of parking, especially on a slope, a parking brake is provided.
For the safe operation of the vehicle, this system must be reliable like no other. It is no coincidence that in the list of malfunctions in which the use of a vehicle is prohibited (an appendix to the Rules of the Road of the Russian Federation), malfunctions of the brake systems are placed in the first place.
Classification of vehicle braking systems
Three to four types of brake systems are installed on modern cars:
- working;
- parking;
- auxiliary;
- spare.
The main and most effective braking system of a car is a working one. It is used throughout the movement to regulate speed and stop completely. Its device is quite simple. It is activated by pressing the brake pedal with the right foot of the driver. This order provides simultaneous deceleration of the engine, by removing the foot from the accelerator pedal, and braking. 
The parking brake system, as the name suggests, is designed to keep the vehicle immobile during long periods of parking. In practice, experienced drivers leave the car in first or reverse gear. However, on large slopes this may not be enough.
The hand brake is also used when starting off on uneven sections of the road, when the right foot should be on the gas pedal, and the left one is depressing the clutch. Gently releasing the brake lever by hand, including the clutch and adding gas at the same time, it is possible to prevent the car from rolling downhill.
The spare brake system is designed to duplicate the main working one in case of its failure. It can be a completely autonomous device, or be a part, one of the brake drive circuits. Alternatively, the parking system can perform the functions of a spare.
The auxiliary brake system is installed on heavy vehicles, for example, on domestic KamAZ, MAZ, KrAZ trucks. It is designed to reduce the load on the main working system during long-term braking - when driving in the mountains or on hilly terrain.
The device of the system and the principle of operation
The main thing in the braking system of any car is the brake mechanisms and their drives. The hydraulic brake actuator used in passenger cars consists of: 
- pedals in the cabin;
- working brake cylinders of the front and rear wheels;
- pipeline (brake pipes);
- brake master cylinder with reservoir.
The principle of operation is as follows - the driver presses the brake pedal, setting the piston of the main brake cylinder in motion. The piston squeezes fluid into the pipelines to the brake mechanisms, which in one way or another create resistance to the rotation of the wheels, and thus braking occurs.
The released brake pedal returns the piston back by means of a return spring, and the fluid flows back into the master cylinder - the wheels are released.
On domestic rear-wheel drive vehicles, the brake system scheme provides for a separate supply of fluid from the master cylinder to the front and rear wheels.
On foreign cars and front-wheel drive VAZs, the pipeline contour scheme “left front - right rear” and “right front - left rear” is used.
Types of brake mechanisms used in cars
The vast majority of cars have friction-type brake mechanisms that work on the principle of friction forces. 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 disc mechanisms on the front. Today, depending on the model, the same types can be placed on all four wheels - either drum or disc.
The device and operation of the drum brake mechanism
The device of the drum-type system (drum mechanism) consists of two shoes, a brake cylinder and a coupling spring, placed on a shield inside the brake drum. Friction linings are riveted or glued onto the pads.
Brake pads with their lower ends are pivotally fixed on supports, and with their upper ends - under the influence of a coupling spring - rest against the pistons of the wheel cylinder. In the unbraked position, there is a gap between the shoes and the drum, which ensures the free rotation of the wheel. 
When fluid enters the cylinder through the brake pipe, the pistons, diverging, push the pads apart. They come into close contact with the brake drum rotating on the hub, and the friction force causes the wheel to brake.
It should be noted that in the above design, the wear of the front and rear pads occurs unevenly. The fact is that the friction linings of the front pad in the direction of travel at the moment of braking when moving forward are always pressed against the drum with more force than the rear ones. As a way out, it is recommended to change the pads in places after a certain period.
Brake mechanism of disk type
The disc brake device consists of:
- a caliper mounted on a suspension, in the body of which there are external and internal brake cylinders (maybe one) and two brake shoes;
- disk attached to the wheel hub.
When braking, the pistons of the working cylinders hydraulically press the brake pads against the rotating disc, stopping the latter.
Comparative characteristics
Drum brakes are easier and cheaper to manufacture. They have a property called the mechanical self-reinforcing effect. That is, with prolonged foot pressure on the pedal, the braking effect increases many times over. This is due to the fact that the lower parts of the pads are connected to each other, and the friction of the front against the drum increases the pressure of the rear pad on it.
However, the disc brake mechanism is smaller and lighter. The temperature resistance is higher, they are cooled faster and better due to the provided window openings. And replacing worn disc pads is much easier than drum pads, which is important if you make repairs yourself.
The principle of operation of the parking brake
It is purely mechanical. It is actuated by lifting the "handbrake" lever to the vertical position until the latch clicks. When this occurs, the 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 release the car from the parking brake, you need to drown the locking button with your finger and lower the lever down to its original position.
Do not forget to check the position of the handbrake before starting the movement! Driving with the handbrake not released will quickly damage the brake pads.
car brake care
As one of the most important components, the brake system of a car requires constant attention and care. Here, literally any malfunction can lead to unpredictable consequences on the road.
Some diagnoses can be made based on the behavior of the brake pedal. So an increased stroke or a “soft” pedal most likely indicate that air has entered the hydraulic drive system as a result of a brake fluid leak. Therefore, it is necessary to periodically check the level of liquid in the tank.
Its increased consumption may be due to damage to hydraulic hoses and tubes, as well as ordinary evaporation over time. This causes air to enter the system and brake failure.
Parts that have become unusable must be replaced, and the system will have to be pumped, releasing air from each working cylinder on the wheels and adding liquid. The process is long and tedious.
The departure of the car during braking to the side indicates a possible failure of one of the working cylinders or excessive wear of the linings on a particular wheel. If the brake mechanisms are dirty, a characteristic noise may occur when you press the pedal.
All these malfunctions are easily eliminated on their own or by contacting a service center. And to minimize the troubles described above, take care of the brakes, use engine braking more often, especially on steep and long descents. Long-term inclusion of the main working system leads to overheating of parts and causes various breakdowns.
Brake system- this is a set of devices designed to regulate the speed of movement, reduce it to the required level or completely stop the car.
Modern cars and wheeled tractors are equipped with working, spare, parking and auxiliary autonomous brake systems.
Service brake system serves to reduce the speed of movement with the desired intensity up to a complete stop of the machine, regardless of its speed, load and slope of the roads for which it is intended.
Spare brake system designed to smoothly reduce the speed of movement or stop the machine in the event of a complete or partial failure of the service brake system (for example, in a KamAZ-4310 car).
The effectiveness of the working and spare brake systems of the machines is evaluated by the braking distance or steady-state deceleration at an initial braking speed of 40 km / h on a straight and horizontal sections of a dry road with a hard surface, providing good grip of the wheels with the road.
Parking brake system serves to keep the machine stationary on a horizontal section of the road or a slope, even in the absence of a driver. The effectiveness of the parking brake system must be able to keep the machine on a slope as steep as it can overcome in low gear.
Auxiliary brake system designed to maintain a constant speed of the machine when driving on long descents of mountain roads and to regulate it independently or simultaneously with the working brake system in order to unload the brake mechanisms of the latter. The effectiveness of the auxiliary brake system should ensure, without the use of other brake systems, the descent of the machine at a speed of 30 km / h along a slope of 7% with a length of 6 km.
Each brake system consists of brake mechanisms (brakes) and a brake actuator.
Braking of the machine is achieved by the work of friction forces in the brake mechanism, which converts the kinetic energy of the machine into heat in the friction zone of the brake linings with the brake drum or disc.
Depending on the type of drive, brake systems are distinguished with hydraulic, pneumatic and pneumohydraulic drive.
Brake mechanisms (brakes) are disc and shoe, and depending on the installation location - wheel and transmission (central). Wheel mounted directly on the wheel hub, and transmission - on one of the transmission shafts.
On heavy vehicles and powerful tractors, braking systems with a pneumatic drive and shoe brakes are most often used.
The shoe brake brakes the pulley 9 with two shoes 5 with friction linings, which are pressed against the pulley 9 from the inside by an expanding cam 4. In this case, the upper ends of the shoes 5 rotate around the fixed hinges (axes) 7. If you release the pedal 1, then the coupling springs 8 will brake the pulley 9.
The disc brake of the MTZ-80 tractor has disks 14 and 16 with friction linings mounted on a rotating shaft 6 with the possibility of movement in the axial direction. Between them there are two pressure disks 12 and 15, connected by earrings 11 with a rod 10 and a brake pedal 1. Expanding balls 13 are installed between the pressure disks in the recesses with bevels. When braking, the balls push the pressure disks apart, which press the rotating disks with friction linings to the stationary crankcase 17 and brake shaft 6.
Drawing. Schemes of wheel brakes: a - shoe; 6 - disk; 1 - pedal; 2 - thrust; 3 - lever; 4 - expanding cam; 5 - block; 6 - braked shaft: 7 - axes turn the pads; 8 - coupling springs; 9 - brake pulley; 10 — draft with an adjusting nut; 11 - earring; 12, 75 - pressure discs; 13 - ball; 14, 16 - discs with friction linings; 17 - crankcase.
The braking system is necessary to slow down the vehicle and bring the vehicle to a complete stop, as well as to hold it in place.
To do this, some brake systems are used on a car, such as a parking, working, auxiliary system and a spare one.
Service brake system used continuously, at any speed, to slow down and stop the vehicle. The service brake system is activated by pressing the brake pedal. It is the most efficient system of all.
Spare brake system used in the event of a main failure. It can be in the form of an autonomous system or its function is performed by a part of a serviceable service brake system.
Parking brake system needed to keep the car in one place. I use the parking system to prevent spontaneous movement of the car.
Auxiliary brake system used on cars with increased weight. The auxiliary system is used for braking on slopes and descents. It often happens that on cars the role of an auxiliary system is played by the engine, where the exhaust pipe is blocked by a damper.
The brake system is the most important integral part of the car, serving to ensure the active safety of drivers and pedestrians. On many vehicles, various devices and systems are used that increase the efficiency of the system during braking - this is an anti-lock braking system (ABS), an emergency brake booster (BAS), a brake booster.
1.3. The main elements of the braking system of a car
The brake system of a car consists of a brake actuator and a brake mechanism.
Fig.1.3. Scheme of the hydraulic drive of the brakes: 1 - pipeline of the circuit "left front-right rear brake"; 2-signal device; 3 - pipeline of the circuit "right front - left rear brake"; 4 - tank of the main cylinder; 5 - the main cylinder of the hydraulic drive of the brakes; 6 - vacuum amplifier; 7 - brake pedal; 8 - rear brake pressure regulator; 9 - parking brake cable; 10 - brake mechanism of the rear wheel; 11 - adjusting tip of the parking brake; 12 - parking brake drive lever; 13 - brake mechanism of the front wheel.
brake mechanism the rotation of the wheels of the car is blocked and as a result, a braking force appears, which causes the car to stop. The brake mechanisms are located on the front and rear wheels of the car.
Simply put, all brake mechanisms can be called shoe. And already, in turn, they can be divided by friction - drum and disk. The brake mechanism of the main system is mounted in the wheel, and behind the transfer case or gearbox is the mechanism of the parking system.
Brake mechanisms, as a rule, consist of two parts, from fixed and rotating. The stationary part is the brake pads, and the rotating part of the drum mechanism is the brake drum.
Drum brakes (Fig. 1.4.) most often stand on the rear wheels of the car. During operation, due to wear, the gap between the block and the drum increases and mechanical regulators are used to eliminate it.
Rice. 1.4. The drum brake mechanism of a back wheel: 1 – a cup; 2 - clamping spring; 3 - drive lever; 4 - brake shoe; 5 - upper coupling spring; 6 - spacer bar; 7 - adjusting wedge; 8 – wheel brake cylinder; 9 - brake shield; 10 - bolt; 11 - rod; 12 - eccentric; 13 - pressure spring; 14 - lower coupling spring; 15 - clamping spring of the spacer bar.
Various combinations of brake mechanisms can be used on cars:
two drum rear, two disc front;
four drums;
four disc.
In disc brake (Fig. 1.5.) - the disk rotates, and two fixed pads are installed inside the caliper. Working cylinders are installed in the caliper, during braking they press the brake pads against the disc, and the caliper itself is securely fixed to the bracket. Ventilated discs are often used to increase heat dissipation from the work area.
Rice. 1.5. Scheme of the disc brake mechanism: 1 - wheel stud; 2 - guide pin; 3 - viewing hole; 4 - support; 5 - valve; 6 - working cylinder; 7 - brake hose; 8 - brake shoe; 9 - ventilation hole; 10 - brake disc; 11 - wheel hub; 12 - dirt cap.
The brake system is designed to control the speed of the car, stop it, and hold it in place for a long time by using the braking force between the wheel and the road. Braking force can be generated by a wheel brake, a vehicle engine (called engine braking), a hydraulic or electric retarder in the transmission.
To implement these functions, the following types of brake systems are installed on the car: working, spare and parking.
Service brake system provides controlled deceleration and stopping of the vehicle.
Spare brake system used in case of failure and malfunction of the working system. It performs similar functions as the working system. A spare brake system can be implemented as a special autonomous system or as part of a working brake system (one of the brake drive circuits).
Depending on the design of the friction part, drum and disc brake mechanisms are distinguished.
The brake mechanism consists of a rotating and a fixed part. As the rotating part of the drum mechanism, a brake drum is used, while the fixed part is brake shoes or bands.
The rotating part of the disc mechanism is represented by a brake disc, the fixed part is represented by brake pads. On the front and rear axles of modern passenger cars, as a rule, disc brakes are installed.
Disc brake consists of a rotating brake disc, two fixed pads mounted inside the caliper on both sides.
caliper fixed on the bracket. Working cylinders are installed in the grooves of the caliper, which, when braking, press the brake pads against the disc.
Brake disk when heated, they get very hot. The brake disc is cooled by air flow. For better heat dissipation, holes are made on the surface of the disk. Such a disk is called ventilated. Ceramic brake discs are used in sports cars to improve braking performance and provide resistance to overheating.
brake pads are pressed against the caliper by spring elements. Friction linings are attached to the pads. On modern cars, brake pads are equipped with a wear sensor.
Brake drive Provides brake control. The brake systems of automobiles use the following types of brake actuators: mechanical, hydraulic, pneumatic, electric and combined.
mechanical drive used in the parking brake system. The mechanical drive is a system of rods, levers and cables that connects the parking brake lever to the brake mechanisms of the rear wheels. It includes the drive lever, adjustable end cables, cable equalizer and shoe drive levers.
On some car models, the parking system is actuated by a foot pedal, the so-called. foot operated parking brake. Recently, an electric drive has been widely used in the parking system, and the device itself is called an electromechanical parking brake.
Hydraulic drive is the main type of drive in the service brake system. The design of the hydraulic drive includes the brake pedal, brake booster, brake master cylinder, wheel cylinders, connecting hoses and pipelines.
The brake pedal transfers force from the driver's foot to the brake master cylinder. The brake booster creates additional force transmitted from the brake pedal. The vacuum brake booster has found the greatest application on cars.
Pneumatic drive used in the brake system of trucks. Combined brake drive is a combination of several drive types. For example, an electro-pneumatic drive.
The principle of operation of the brake system
The principle of operation of the brake system is considered on the example of a hydraulic working system.
When you press the brake pedal, the load is transferred to the amplifier, which creates additional force on the main brake cylinder. The brake master cylinder piston pumps fluid through pipes to the wheel cylinders. This increases the fluid pressure in the brake actuator. The pistons of the wheel cylinders move the brake pads to the discs (drums).
Further pressure on the pedal increases the fluid pressure and the brakes are activated, which slows the rotation of the wheels and the appearance of braking forces at the point of contact of the tires with the road. The more force is applied to the brake pedal, the faster and more efficiently the wheels are braked. The fluid pressure during braking can reach 10-15 MPa.
At the end of braking (releasing the brake pedal), the pedal under the influence of a return spring moves to its original position. The piston of the main brake cylinder moves to its original position. Spring elements move the pads away from the discs (drums). The brake fluid from the wheel cylinders is forced through pipelines into the master brake cylinder. The pressure in the system drops.
The effectiveness of the braking system is significantly increased through the use of active vehicle safety systems.
Cars are one of the most advanced inventions of mankind. Their features of operation determine that all systems should work as efficiently as possible, all possible cases during operation are provided for at the time of designing each model. All this is due to the fact that while driving at high speed there is a danger to those who are inside the vehicle, and to those who are outside. The systems that are designed to increase traffic safety include the brake mechanism. He gets a lot of attention.
Purpose of the braking system
The brake system is used to regulate the speed of movement or to fix the car during rest. Special handling skills allow you to use the brakes for sharp, complex maneuvers that do not involve slowing down.
If the engine and other systems allow you to pick up speed, then the brakes reset it. Naturally, the more reliable and perfect they are, the better braking occurs.
History of creation
In order to understand the principle of operation of a system that can reduce speed in a few seconds, you should pay attention to the history of its creation. Such a perfect system was not obtained immediately, but through trial and error, which determined both the name of the systems and their performance.
The history of the creation of the first mechanisms that made it possible to reduce speed begins with horse-drawn transport. At high speeds, the horse itself could not stop the wagon quickly, so they began to use leverage systems when a block was pressed against the rim. Until 1920, a similar system was used on the first cars.
Then, in one trip, I had to change the leather lining several times, as it quickly wore out. A similar but improved system is still used on speed bikes to this day.
At the beginning of the 20th century, cars began to accelerate to speeds above 100 km / h. It was then that it became clear that it was the brake system that did not allow improving the car. An interesting fact is that it was disc brakes that appeared first. However, the materials used in the manufacture determined a strong grinding at the time of movement. Therefore, drum systems have become very popular. At that time, they were only enough for 2 thousand of the distance traveled.
Until 1953, drum brake systems were being improved. And only after this year was developed a different system, which was based on the use of disks. After that, the design will be improved when creating modern cars.
Classification of brake systems
There are quite a few options for the execution of brake systems. Not all of them are used in the design of cars. By purpose, the following classification can be distinguished:
- The working purpose mechanism is necessary to regulate the speed of the machine while driving. This version of the performance is the most popular, as it is used throughout the entire movement. Recently, the design of such a system has become much more complicated by including various devices for controlling force, wheel slippage, and so on.
- The parking type brake is applied at the moment of parking or short-term stop. According to the established rules, it is the parking brake that should be used at the time of stopping downhill, at traffic lights and in other similar cases. Often, systems can be activated using a special lever; modern cars have an electric switch. On passenger cars, a cable is laid from the lever, which immediately goes to the rear wheels. Trucks have an air system with installed power accumulators.
You can also note the auxiliary brake system, which is often included in the design of trucks and buses. Her work is based on blocking the exhaust pipe, which supplies fuel to the engine. Use the system for a long descent, as the worker can overheat and lose its effectiveness. We will also consider what kind of brakes There are also drive types.
An important indicator can also be called what type of system sets in motion an actuator that directly performs braking. According to this indicator, we can distinguish:
- Mechanical drive. Used on older cars. It has high reliability, but low efficiency. Mechanical drive was based on the use of a system of rods to set the executive body in motion, when you press the pedal.
- Hydraulic has been widely used in the creation of modern cars. Its operation is based on the incompressibility of the working fluid used. The system is represented by several executive bodies, and the pressure is transmitted using a fluid.
- The pneumatic system is powered by compressed air. Like liquids, gaseous substances have a compressibility limit. That is why gaseous substances, often air, are used to transfer force.
- There is also a combined version, when both air and liquid are used in the system. Often a similar system can be found on trucks and buses.
- The electronic version is used extremely rarely, since the reliability of such a system is at a relatively low level. As a rule, the simpler the system, the more reliable it is. That is why the installation of an electric brake system is rarely carried out, when the command to the executive body is transmitted using electricity.
The type of drive to a greater extent determines the features of the brake system.
In addition to the above features, the type of executive body should also be noted. According to this indicator, the following systems can be distinguished:
- The combination of a drum and a clamping mechanism with pads was previously the most common actuator, which is often installed on buses and cars of category "C". Its feature can be called the fact that the friction force occurs inside the drum.
- A brake system based on a disc and a clamping caliper is used in the creation of all modern cars. A feature of this system is the combination of a disc that rotates with the wheel, and a caliper that compresses the brake pads.
The most effective system is considered to be a combination of disc and caliper. The use of new materials in the manufacture of linings that create a friction force can significantly increase the reliability of the system under consideration.
Benefits of disc brakes
When considering almost all modern passenger cars, it should be noted that they have a disk system. This is due to the following points:
- The design is much simpler, which means cheaper and more reliable.
- The gap is automatically adjusted when the overlays are erased.
- The design is more compact and lighter, allowing the creation of fast sports cars.
- Despite the reduction in pad area, the efficiency of such a system is much higher. This is due to the fact that the disc and pads have a flat surface, and this ensures uniform pressing.
- Easier to service. It is not necessary to limit downforce.
- Better cooling as the air circulates freely. It is worth noting that overheating often leads to a significant deterioration in the performance of the brakes. Therefore, to increase the cooling efficiency, special rims are used.
- The pollution products are easily removed. A large amount of dirt often accumulates in the drum, which causes a decrease in the efficiency of the system.
However, when creating such a design, some difficulties were also identified. An example is the need for a large force, which became possible when using only a hydraulic drive. A mechanism is also installed that allows you to reduce the required effort when you press the pedal.
