Repair of the brake system VAZ 2101. Materials

In the brake system of the Zhiguli car, many design solutions have been applied that have not previously been seen on domestic passenger cars - front wheel disc brakes, a dual master brake cylinder, a pressure limiter, aluminum rear brake drums. Since they are unfamiliar to most motorists, we will pay special attention to them.
First of all, it must be said about the dual-circuit hydraulic brake drive system. For the first time, two independent circuits of pipelines supplying fluid to the brakes of the front and rear wheels appeared in the late 30s on racing cars, where brake reliability is of paramount importance. If a hose breaks or fluid leaks in one circuit, the other circuit does not fail, and the machine can be braked. A few years ago, this solution was borrowed by the designers of mass-produced passenger cars. The two master cylinders that run in parallel on racing cars are placed one behind the other in a common housing to make the assembly more compact. Disc brakes have also been inherited by passenger cars from their racing counterparts, where they have been used successfully for seventeen years now. The higher efficiency of disc brakes compared to drum brakes is the reason why they are most often equipped with front wheels, which account for a significant part of the braking force.
The rear brakes of the Zhiguli are made of drums, as they are less loaded. In addition, this design simplifies the drive of the hand brake. It was also taken into account that the rear disc brakes, "shelled" by a stream of dirt and dust from under the front wheels, would wear out too quickly when operating the car on country roads.
So that the rear brakes of the Zhiguli were not heavy and cooled well, they were equipped with aluminum drums with cast-iron rings poured into them, on which the pads work.
Another important feature of the Zhiguli brake system is the pressure regulator. With a sharp braking of the car, a redistribution of loads always occurs - the car “pecks” with its nose, and the load on the rear wheels decreases. As a result, their grip on the road deteriorates, and they "go skidding". This phenomenon (if the drive wheels are rear), especially when driving on a snowy and wet road, leads to skidding of the rear of the car, and sometimes to accidents - in this case, the car loses control.
Obviously, depending on the load on the rear wheels (the number of passengers, the amount of luggage, the redistribution of weight during heavy braking), it is necessary to regulate the fluid pressure, and hence the braking force on the rear wheels. Then "use" will be prevented. The sensor of such an “automatic” regulator is a mechanical connection between the rear axle and the body, the distance between which varies precisely depending on the load on the rear axle.
Let us now consider specifically each node of the system.

Installing the brake pedal:

2 - pusher;
3 - pedal;
4 - adjustable stop and brake light switch;
5 - locknut;
6 - withdrawal spring;
7 - pedal bracket.

As on most modern passenger cars, the brake pedal is made suspended and is attached together with the clutch pedal to the axis of the bracket 7. With its end, it is pressed against the front panel of the body and (screwed to it together with the main brake and clutch cylinders with nuts on four studs. Pedal 3 through the pusher 2 acts on the piston of the main brake cylinder, which supplies fluid to the brakes.When the pedal is moved, the brake light switch 4 is immediately activated, on the pusher of which it rests in its original position.The full pedal travel is about 140 mm.

Master brake cylinder:
1 - cork;
2 - body;
3 - rear brake drive piston;
4 - front brake drive piston;
5, 9 - sealing ring;
6, 10 - fixing bolt;
7, 11 - spring;
8 - thrust washer;
12 - adjusting ring;
13 - inlet;
14 - clamping spring.

In the cast-iron housing 2 of the main brake cylinder, two pistons 3 and 4 are placed, serving the brakes, respectively, of the rear and front wheels. Their travel is limited by fixing bolts 6 and 10 included in the longitudinal grooves. Each piston is provided with a return spring 7 (or 11) and a sealing system. When you press the pedal, piston 4 moves to the left. The brake fluid that came from the tank into the cavity between the left end of the piston and the ring 12 enters through the drilling 13 into the space between the piston and the washer 8, goes further along the corresponding channel to the front brake pipelines and simultaneously presses on the piston 3. It shifts it to the left, with In this case, the path of the brake fluid under piston 3 is the same as under piston 4. Under the action of piston 3, the fluid is supplied to the rear brakes.
At the beginning of the stroke of each of the pistons, the rings 12, tightly seated in the bore of the cylinder body 2, remain in place. Then the gaps between them and the ends of the pistons are selected, the pistons push the rings to the left, and the springs 14, pressing the rubber rings 9 against the ends of the pistons, prevent further communication of the cavity under the piston with the fluid reservoir. These devices perform the work of the well-known reed valve. The role of sealing cuffs is played by three rings 9.
When the system is working properly in the rear brake drive circuit, the connection between pistons 3 and 4 is hydraulic. In the event of a fluid leak or a hose break, piston 3 “falls through”, compressing spring 11. Having reached the stop, it becomes a fixed wall in the cylinder for its partner, allowing fluid to be supplied under pressure to a working front brake drive circuit. When the pressure drops in the front brake drive circuit, piston 4 compresses spring 7 and rests against piston 3 with its end, forcing it to supply fluid to its circuit.
The master cylinder is fed with fluid from tanks connected to the front and rear brake drive cavities by hoses. With the working cylinders of the front and rear brakes, the master cylinder is connected, respectively, by pipelines.

Regulator installation:
1 - rear axle beam;
2 - earring;
3 - bracket;
4 - torsion bar;
5 - body bracket;
6 - regulator.

Before getting into the working cylinders of the rear brakes, the fluid enters the pressure regulator. It is installed on the bracket 5 of the body near the beam 1 of the rear axle and is connected to it by the earring 2 and the torsion bar 4.

Rear wheel brake force regulator:
1 - body;
2 - ring;
3, 8 - sealant;
4 - torsion bar;
5 - piston;
6 - spring;
7 - thrust ring;
9 - cork.

The torsion bar, depending on the distance between the body and the beam 1, exerts variable pressure on the mushroom-shaped piston 5 of the regulator. Due to the fact that the area of ​​the upper end of the piston is larger than the area of ​​the lower shoulder of its head, as the fluid pressure increases, a hydrostatic force arises that tends to lower the piston. If the pressure is too high, which can lead to the “skid” of the wheels, it drops so much that, leaning on the rubber ring 8, it cuts off the fluid supply to the wheel cylinders. Thus, the fluid pressure at the outlet of the regulator is always lower than at the inlet. The downward movement of the piston 5 is prevented by the end of the torsion bar supporting it. The closer the rear axle beam to the body (hence, the greater the load on the rear axle), the stronger the pressure of the torsion bar on the piston. This means that fluid is supplied to the wheel cylinders at a higher (in proportion to the load) pressure.
The parameters of the regulator are chosen so that the fluid pressure in the brake cylinders of the rear wheels never exceeds a value that is dangerous in relation to blocking the wheels.

Brake device:
1 - main brake cylinder;
2 - pipeline to the rear brakes;
3 - hoses for supplying fluid from tanks;
4 - equalizing hose;
5 - tanks for brake fluid;
6 - pipelines to the front brakes;
7 - flexible hose;
8 - bracket;
9 - brake pads;
10 - cuff;
11 - sealing ring;
12 - connecting tube;
13 - fitting for bleeding the brakes;
14 - piston;
15, 16 - working cylinder;
17 - wheel;
18 - wheel bolt;
19 - protective cover;
20 - brake disc;
21 - wheel hub;
22 - bracket bracket;
23 - front suspension strut;
24, 31 - bolt;
25 - wheel cylinder;
26, 38 - block;
27 - overlay;
28 - lever;
29, 36 - eccentric;
30 - support shield:
32 - tip;
33 - cable;
34 - axes of pads;
35, 39 - spring;
37 - spacer bar.

Let us now turn directly to the device of the brake mechanisms. Cast-iron brake discs 20 are attached to the flanges of the hubs 21 of the front wheels. Each disc is covered by a caliper, or bracket 8, which is screwed with two bolts 24 to the bracket 22 mounted on the front suspension strut 23. Aluminum working brake cylinders 15 and 16 with pistons 14 are installed in special grooves of the cast-iron bracket 8.
When you press the pedal, the brake fluid enters the cylinders through pipes 7 and 12 and moves the pistons towards each other (their stroke is 0.1 mm). The pistons, resting against the brake pads with linings 9, clamp the disk 20, slowing down its rotation, and, consequently, the wheels 17.
When released, when the fluid pressure drops, the pistons 14 due to the elasticity of the sealing rings 11 return to their original position. Special devices for adjusting the gap between discs 20 and pads 9 are not required, since under the action of even a slight axial runout, the disc presses the pads, regardless of their wear, to the desired amount, maintaining the required minimum gap. The pads are protected from dirt, leading to premature wear, by a protective cover. Brake linings are of considerable thickness and need to be replaced (a simple operation that does not take much time) only when their thickness is reduced to 1.5 mm.
It should be noted that disc brakes do not lose their effectiveness when water gets on them: the discs almost instantly shed a wet film from themselves.
The rear drum brakes are made according to the generally accepted scheme. Pistons located inside the working cylinder 25 push apart the shoes 26 and 38 associated with them, pressing them against the brake drum. The axles 34 of the pads and the cylinder 25 are fixed on the support shield 30, which is screwed to the flange of the rear axle beam with four bolts 31. The hand brake acts on the same pads 26 and 38 by means of cables 33 through the intermediate lever 28 and the spacer bar 37.
The handbrake lever is equipped with a ratchet device that locks it in the raised (tightened) position.
The gap between the pads and drums is adjusted by turning the eccentrics 29 and 36, on which the brake pads rest. The hexagonal heads of the eccentrics, which serve to turn them, are removed from the brake shield.
A few words about the care of the brake system. It is described in detail in the factory manual. However, it is useful, as operating experience shows, to warn owners that it is unacceptable to use any other brake fluid other than that recommended by the factory (GTZHA-2 Neva), and also to mix this fluid with others.

This brake system has two circuits that provide independent drive of the front and rear wheel brakes. Both circuits are driven by one pedal 17 (see fig. Brake system diagram), which, using a bracket, is attached together with the clutch pedal to the front panel of the body.

In addition to the brake pedal, the hydraulic drive includes the main brake cylinder 21, the reservoir 4 of the master cylinder, the rear brake pressure regulator 9, the brakes of the front and rear wheels together with the working cylinders and pipelines.

Master brake cylinder

The brake master cylinder is attached to the clutch and brake pedal bracket. Pistons 3 and 5 (see fig. Hydraulic brake master cylinder) actuate different circuits. Both pistons take their initial position under the action of springs 8, which press the pistons all the way into the screws 7. The tightness of the pistons in the cylinder is ensured by four sealing rings 6. The housing is closed at the front
cork 1.

Pedal assembly

Pedals 6 (see fig. Clutch and brake pedal bracket parts) and 19 are suspended on the bracket 1 by means of an axle made in the form of a bolt.

Axis 18 is fixed with nut 2 in the holes of the cheeks of the bracket. On the axis between the cheeks of the bracket and the distance sleeve 7, the inner sleeves 4 and 14 of the clutch and brake pedals are clamped. Pedals are pivotally mounted on these bushings, in the hubs of which outer bushings 5 ​​and 9 are pressed in. Pushers 20 are pivotally attached to both pedals, acting on the pistons of the hydraulic cylinders. The reverse travel of the clutch pedal is limited by the buffer 11 mounted on the head of the bolt 12. The main cylinders of the clutch release drive and the brake drive are attached to the bracket shelf.

pressure regulator

Regulator 9 is connected to the rear brake drive circuit (see Fig. Brake system diagram) pressure, which corrects the pressure in the rear brake drive depending on the position of the body relative to the rear axle beam, i.e. depending on vehicle load. It acts as a restrictor valve, automatically cutting off the flow of brake fluid to the rear brakes, reducing the chance of rear wheel skidding when braking.

The regulator is mounted on the body bracket and connected to the rear axle beam through the torsion lever 12 (see Fig. Pressure Regulator Drive Parts) and thrust 7. The other end of the torsion lever acts on the piston 10 (see Fig. Rear brake pressure regulator in non-working position).

Fluid enters cavity A from the master cylinder, and from cavity B it exits into the wheel cylinders of the rear brake drive.

The force P acting on the piston from the torsion lever increases as the body approaches the axle beam and decreases as the body moves away from the rear axle beam.

Before the pressure regulator begins to act, piston 10 abuts against plug 6 under the action of force P and spring 9. In this case, gaps are formed through which cavities A and B communicate, i.e. the pressure in them will be the same and equal to the pressure in the hydraulic brake drive.

When the brakes are applied, the rear of the car rises by inertia and, consequently, the pressure on the piston from lever 1 decreases. The force of fluid pressure on the upper end of the piston with a larger surface area at some point exceeds the pressure force of the fluid acting on the piston from below, and the piston will go down until it stops in seal 7. At the same time, cavities A and B will be separated, and different pressures will be created in them: in cavity A, the pressure Pa will be equal to the pressure in the main cylinder, and in cavity B, the pressure Pv will be less by the value that determines the balance of the piston, which is under the action of pressure Pa and Pb, spring 9 and the force of the torsion lever. Thus, partial or complete separation of cavities A and B by piston 10 regulates the braking torque on the rear wheels.

The brake mechanism of a forward wheel is disk. It consists of the ones shown in Fig. Front wheel brake (Front wheel brake caliper parts) caliper 12 (4) assembled with working cylinders 17, brake disc 18, two brake shoes 16 (11), connecting pins 8 (8) and pipelines.

The caliper is attached to the bracket 11 with two bolts 9, which are locked by bending the bolts of the locking plates to the edge. The bracket 11, in turn, is attached to the flange of the steering knuckle 10 together with the protective cover 13 and the rotary lever. The caliper has a radial groove through which the brake disc 18 passes and two transverse grooves for accommodating brake pads 16. The lugs of the caliper have two windows with guide grooves in which two opposite cylinders 17 are installed. To fix the cylinders relative to the caliper, a spring lock is installed in the cylinder 4, included in the side groove of the caliper.

Each cylinder has a piston 3 (1), which is sealed with an elastic rubber ring 6 (3). It is located in the groove of the cylinder and tightly compresses the surface of the piston. The cylinder cavity is protected from contamination by a rubber cap 7 (2).

The working cavities of the cylinders are interconnected by pipeline 2 (5). A fitting 1 (6) is screwed into the outer cylinder for bleeding the front brake drive circuit, into the inner cylinder - a hose fitting for supplying brake fluid.

Piston 3 rests against brake pads 16, on which pads 5 are glued. The pads are mounted on pins 8 and are pressed against them by springs 15 (7). Pins 8 are held in the cylinder by cotter pins 14 (9).

The brake disc 18 is attached to the wheel hub with two dowel pins.

Rear wheel brake

The brake mechanism of a back wheel of drum type, with self-adjusting pads. Brake shoes 3 with pads 7 (see fig. Rear wheel brake), wheel cylinder 1 and other parts are mounted on the brake shield, which is attached to the flange of the rear axle beam. A package of plates is attached to the bottom of the shield with two rivets, one of which is a support for the lower ends of the brake pads. To regulate the gap between the shoes and the drum, eccentrics 8 are used, on which the shoes rest under the action of the coupling springs 5 ​​and 10.

In case 4 (see fig. Wheel cylinder parts) of the wheel cylinder, there are two pistons 2, which are expanded by a spring 7 with support cups 5. Seals 3 are pressed against the end of the pistons by the same spring.

Stops are pressed into the pistons, into the grooves of which the upper ends of the brake pads rest. The outlet of the pistons from the cylinders is sealed with rubber caps 1. To bleed the rear brake drive, a fitting 6 is screwed into the cylinder.

This brake system has two circuits that provide independent drive of the front and rear wheel brakes. Both circuits are actuated from one pedal 17 (see Fig. Diagram of the brake system), which, using a bracket, is attached together with the clutch pedal to the front panel of the body.

Scheme of the brake system VAZ 2101, 2102

In addition to the brake pedal, the hydraulic drive includes the main brake cylinder 21, the reservoir 4 of the master cylinder, the rear brake pressure regulator 9, the brakes of the front and rear wheels together with the working cylinders and pipelines.

Master brake cylinder VAZ 2101, 2102

Hydraulic brake master cylinder

The brake master cylinder is attached to the clutch and brake pedal bracket. Pistons 3 and 5 (see Fig. Hydraulic brake master cylinder) actuate different circuits. Both pistons take their initial position under the action of springs 8, which press the pistons all the way into the screws 7. The tightness of the pistons in the cylinder is ensured by four sealing rings 6. The housing is closed at the front
cork 1.

Pedal assembly

Pedals 6 (see Fig. Details of the bracket of the clutch and brake pedals) and 19 are suspended on the bracket 1 by means of an axle made in the form of a bolt.

Clutch and brake pedal bracket parts

Axis 18 is fixed with nut 2 in the holes of the cheeks of the bracket. On the axis between the cheeks of the bracket and the distance sleeve 7, the inner sleeves 4 and 14 of the clutch and brake pedals are clamped. Pedals are pivotally mounted on these bushings, in the hubs of which outer bushings 5 ​​and 9 are pressed in. Pushers 20 are pivotally attached to both pedals, acting on the pistons of the hydraulic cylinders. The reverse travel of the clutch pedal is limited by the buffer 11 mounted on the head of the bolt 12. The main cylinders of the clutch release drive and the brake drive are attached to the bracket shelf.

Pressure regulator VAZ 2101, 2102

A pressure regulator 9 is connected to the rear brake drive circuit (see Fig. Brake system diagram - above), which adjusts the pressure in the rear brake drive depending on the position of the body relative to the rear axle beam, i.e. depending on vehicle load. It acts as a restrictor valve, automatically cutting off the flow of brake fluid to the rear brakes, reducing the chance of rear wheel skidding when braking.

The regulator is mounted on the body bracket and connected to the rear axle beam through the torsion lever 12 (see Fig. Details of the pressure regulator drive) and rod 7. The other end of the torsion lever acts on the piston 10 (see Fig. Rear brake pressure regulator in non-working position) .

Pressure Regulator Drive Parts

Rear brake pressure regulator in non-working position

Fluid enters cavity A from the master cylinder, and from cavity B it exits into the wheel cylinders of the rear brake drive.

The force P acting on the piston from the torsion lever increases as the body approaches the axle beam and decreases as the body moves away from the rear axle beam.

Before the pressure regulator begins to act, piston 10 abuts against plug 6 under the action of force P and spring 9. In this case, gaps are formed through which cavities A and B communicate, i.e. the pressure in them will be the same and equal to the pressure in the hydraulic brake drive.

When the brakes are applied, the rear of the car rises by inertia and, consequently, the pressure on the piston from lever 1 decreases. The force of fluid pressure on the upper end of the piston with a larger surface area at some point exceeds the pressure force of the fluid acting on the piston from below, and the piston will go down until it stops in the seal 7. At the same time, the cavities A and B will be separated, and different pressures will be created in them: in the cavity A, the pressure Pa will be equal to the pressure in the master cylinder, and in the cavity B, the pressure Pv will be less by the value that determines the balance of the piston, which is under the action of pressure Pa and Pb, spring 9 and the force of the torsion lever. Thus, partial or complete separation of cavities A and B by piston 10 regulates the braking torque on the rear wheels.

Brake mechanism of the front wheel VAZ 2101, 2102

The brake mechanism of a forward wheel is disk. It consists of the ones shown in Fig. The front wheel brake mechanism (Details of the front wheel brake caliper) of the caliper 12 (4) complete with working cylinders 17, brake disc 18, two brake shoes 16 (11), connecting fingers 8 (8) and pipelines.

Front wheel brake

Front wheel brake caliper parts

The caliper is attached to the bracket 11 with two bolts 9, which are locked by bending the bolts of the locking plates to the edge. The bracket 11, in turn, is attached to the flange of the steering knuckle 10 together with the protective cover 13 and the rotary lever. The caliper has a radial groove through which the brake disc 18 passes and two transverse grooves for accommodating brake pads 16. The lugs of the caliper have two windows with guide grooves in which two opposite cylinders 17 are installed. To fix the cylinders relative to the caliper, a spring lock is installed in the cylinder 4, included in the side groove of the caliper.

Each cylinder has a piston 3 (1), which is sealed with an elastic rubber ring 6 (3). It is located in the groove of the cylinder and tightly compresses the surface of the piston. The cylinder cavity is protected from contamination by a rubber cap 7 (2).

The working cavities of the cylinders are interconnected by pipeline 2 (5). A fitting 1 (6) is screwed into the outer cylinder for bleeding the front brake drive circuit, into the inner cylinder - a hose fitting for supplying brake fluid.

Piston 3 rests against brake pads 16, on which pads 5 are glued. The pads are mounted on pins 8 and are pressed against them by springs 15 (7). Pins 8 are held in the cylinder by cotter pins 14 (9).

The brake disc 18 is attached to the wheel hub with two dowel pins.

Brake mechanism of the rear wheel VAZ 2101, 2102

The brake mechanism of a back wheel of drum type, with self-adjusting pads. Brake pads 3 with pads 7 (see Fig. Rear wheel brake mechanism), wheel cylinder 1 and other parts are mounted on the brake shield, which is attached to the flange of the rear axle beam. A package of plates is attached to the bottom of the shield with two rivets, one of which is a support for the lower ends of the brake pads. To regulate the gap between the shoes and the drum, eccentrics 8 are used, on which the shoes rest under the action of the coupling springs 5 ​​and 10.

In the housing 4 (see. Fig. Details of the wheel cylinder) of the wheel cylinder, there are two pistons 2, which are bursting with a spring 7 with support cups 5. Seals 3 are pressed against the end of the pistons by the same spring.

Wheel cylinder parts

Stops are pressed into the pistons, into the grooves of which the upper ends of the brake pads rest. The outlet of the pistons from the cylinders is sealed with rubber caps 1. To bleed the rear brake drive, a fitting 6 is screwed into the cylinder.

This brake system has two circuits that provide independent drive of the front and rear wheel brakes. Both circuits are actuated from one pedal 17 (see Fig. Diagram of the brake system), which, using a bracket, is attached together with the clutch pedal to the front panel of the body.

Scheme of the brake system VAZ 2101, 2102

In addition to the brake pedal, the hydraulic drive includes the main brake cylinder 21, the reservoir 4 of the master cylinder, the rear brake pressure regulator 9, the brakes of the front and rear wheels together with the working cylinders and pipelines.

Master brake cylinder VAZ 2101, 2102

Hydraulic brake master cylinder

The brake master cylinder is attached to the clutch and brake pedal bracket. Pistons 3 and 5 (see Fig. Hydraulic brake master cylinder) actuate different circuits. Both pistons take their initial position under the action of springs 8, which press the pistons all the way into the screws 7. The tightness of the pistons in the cylinder is ensured by four sealing rings 6. The housing is closed at the front
cork 1.

Pedal assembly

Pedals 6 (see Fig. Details of the bracket of the clutch and brake pedals) and 19 are suspended on the bracket 1 by means of an axle made in the form of a bolt.

Clutch and brake pedal bracket parts

Axis 18 is fixed with nut 2 in the holes of the cheeks of the bracket. On the axis between the cheeks of the bracket and the distance sleeve 7, the inner sleeves 4 and 14 of the clutch and brake pedals are clamped. Pedals are pivotally mounted on these bushings, in the hubs of which outer bushings 5 ​​and 9 are pressed in. Pushers 20 are pivotally attached to both pedals, acting on the pistons of the hydraulic cylinders. The reverse travel of the clutch pedal is limited by the buffer 11 mounted on the head of the bolt 12. The main cylinders of the clutch release drive and the brake drive are attached to the bracket shelf.

Pressure regulator VAZ 2101, 2102

A pressure regulator 9 is connected to the rear brake drive circuit (see Fig. Brake system diagram - above), which adjusts the pressure in the rear brake drive depending on the position of the body relative to the rear axle beam, i.e. depending on vehicle load. It acts as a restrictor valve, automatically cutting off the flow of brake fluid to the rear brakes, reducing the chance of rear wheel skidding when braking.

The regulator is mounted on the body bracket and connected to the rear axle beam through the torsion lever 12 (see Fig. Details of the pressure regulator drive) and rod 7. The other end of the torsion lever acts on the piston 10 (see Fig. Rear brake pressure regulator in non-working position) .

Pressure Regulator Drive Parts

Rear brake pressure regulator in non-working position

Fluid enters cavity A from the master cylinder, and from cavity B it exits into the wheel cylinders of the rear brake drive.

The force P acting on the piston from the torsion lever increases as the body approaches the axle beam and decreases as the body moves away from the rear axle beam.

Before the pressure regulator begins to act, piston 10 abuts against plug 6 under the action of force P and spring 9. In this case, gaps are formed through which cavities A and B communicate, i.e. the pressure in them will be the same and equal to the pressure in the hydraulic brake drive.

When the brakes are applied, the rear of the car rises by inertia and, consequently, the pressure on the piston from lever 1 decreases. The force of fluid pressure on the upper end of the piston with a larger surface area at some point exceeds the pressure force of the fluid acting on the piston from below, and the piston will go down until it stops in the seal 7. At the same time, the cavities A and B will be separated, and different pressures will be created in them: in the cavity A, the pressure Pa will be equal to the pressure in the master cylinder, and in the cavity B, the pressure Pv will be less by the value that determines the balance of the piston, which is under the action of pressure Pa and Pb, spring 9 and the force of the torsion lever. Thus, partial or complete separation of cavities A and B by piston 10 regulates the braking torque on the rear wheels.

Brake mechanism of the front wheel VAZ 2101, 2102

The brake mechanism of a forward wheel is disk. It consists of the ones shown in Fig. The front wheel brake mechanism (Details of the front wheel brake caliper) of the caliper 12 (4) complete with working cylinders 17, brake disc 18, two brake shoes 16 (11), connecting fingers 8 (8) and pipelines.

Front wheel brake

Front wheel brake caliper parts

The caliper is attached to the bracket 11 with two bolts 9, which are locked by bending the bolts of the locking plates to the edge. The bracket 11, in turn, is attached to the flange of the steering knuckle 10 together with the protective cover 13 and the rotary lever. The caliper has a radial groove through which the brake disc 18 passes and two transverse grooves for accommodating brake pads 16. The lugs of the caliper have two windows with guide grooves in which two opposite cylinders 17 are installed. To fix the cylinders relative to the caliper, a spring lock is installed in the cylinder 4, included in the side groove of the caliper.

Each cylinder has a piston 3 (1), which is sealed with an elastic rubber ring 6 (3). It is located in the groove of the cylinder and tightly compresses the surface of the piston. The cylinder cavity is protected from contamination by a rubber cap 7 (2).

The working cavities of the cylinders are interconnected by pipeline 2 (5). A fitting 1 (6) is screwed into the outer cylinder for bleeding the front brake drive circuit, into the inner cylinder - a hose fitting for supplying brake fluid.

Piston 3 rests against brake pads 16, on which pads 5 are glued. The pads are mounted on pins 8 and are pressed against them by springs 15 (7). Pins 8 are held in the cylinder by cotter pins 14 (9).

The brake disc 18 is attached to the wheel hub with two dowel pins.

Brake mechanism of the rear wheel VAZ 2101, 2102

The brake mechanism of a back wheel of drum type, with self-adjusting pads. Brake pads 3 with pads 7 (see Fig. Rear wheel brake mechanism), wheel cylinder 1 and other parts are mounted on the brake shield, which is attached to the flange of the rear axle beam. A package of plates is attached to the bottom of the shield with two rivets, one of which is a support for the lower ends of the brake pads. To regulate the gap between the shoes and the drum, eccentrics 8 are used, on which the shoes rest under the action of the coupling springs 5 ​​and 10.

In the housing 4 (see. Fig. Details of the wheel cylinder) of the wheel cylinder, there are two pistons 2, which are bursting with a spring 7 with support cups 5. Seals 3 are pressed against the end of the pistons by the same spring.

Wheel cylinder parts

Stops are pressed into the pistons, into the grooves of which the upper ends of the brake pads rest. The outlet of the pistons from the cylinders is sealed with rubber caps 1. To bleed the rear brake drive, a fitting 6 is screwed into the cylinder.

• 1. Front brake wheel cylinder:
• 2. Wheel cylinder piston:
• 3. Front brake caliper:
• 4. Sealing ring;
• 5. Dust Ring:
• 6. Brake pads:
• 7. Brake bleeder:
• 8. Disc Brake:
• 9. Brake pad pin:
• 10. Rear brake drive piston;
• 11. Sealing ring:
• 12. Piston stop screw:
• 13. Front brake piston:
• 14. Spacer sleeve:
• 15. Master cylinder:
• 16. Pusher;
• 17. Brake pedal:
• 18. Stop lamp switch:
• 19. Stoplight switch:
• 20. Pedal release spring;
• 21. Union;
• 22. Support cup:
• 23. master cylinder reservoir:
• 24. Float:
• 25. Pusher:
• 26. Fixed contact;
• 27. moving contact;
• 28. Rear brake pad:
• 29. Parking brake lever:
• 30. Pad thrust:
• 31. Wheel cylinder piston;
• 32. Rear brake wheel cylinder:
• 33. Piston spacer;
• 34. Friction lining pads;
• 35. Brake drum:
• 36. Pressure regulator body plug;
• 37. Piston head seal:
• 38. Spring plate:
• 39. Spring support washer:
• 40. Piston O-Ring:
• 41. Pressure regulator piston;
• 42. Pressure regulator drive lever;
• 43. Pressure regulator piston spring;
• 44. Sleeve:
• 45. pressure regulator housing;
• 46. I. Braking;
• 47. II. Complete release;
• 48. III. The pressure P1 in the master cylinder is equal to the pressure P2 in the wheel cylinders of the rear brakes:
• 49. IV. The pressure P1 in the main cylinder is greater than the pressure P2 in the wheel cylinders of the rear wheels;
• 50. V. Brake fluid in a free state;
• 51. VI.High pressure brake fluid.

When the system is disengaged and the brake pedal under the action of the spring 20 is pulled to the stop against the stoplight switch 19, then the pusher 16 is pulled together with the pedal. The pistons 10 and 13 of the master cylinder are pressed into the rear extreme position under the action of the return springs until they stop against the limit screws 12. In this position, the spacer sleeves 14, resting against the screws 12, squeeze the sealing rings And from the end of the piston groove and through the resulting gaps, the working cavities of the cylinder communicate with the hydraulic cylinder reservoir and high-pressure pipelines. Thus, there is no pressure in the brake actuator. Therefore, the pistons 2 under the action of elastic deformation of the sealing rings 4 are retracted into the cylinders and do not exert pressure on the brake pads of the front brakes, which will be in light contact with the surface of the brake disc. When the car is moving without braking, that is, when there is no pressure in the hydraulic drive, the piston 41 under the action of the spring 43 and the torsion lever 42 is raised up until it stops in the plug 36. Therefore, the housing cavities above and below the piston head are freely communicated. This opens the free passage of fluid to the rear brake wheel cylinders. But since there is no pressure in the entire brake drive, the brake shoes 28 are pressed from the drums by coupling springs. When braking, when the driver presses the brake pedal, the pusher 16 moves the piston 13. When the piston 13 moves, the spacer sleeve 14 moves away from the restrictive screw 12 and the sealing ring 11 is pressed against the end face of the piston groove by a spring. Thus, the compensation gap is blocked and the cavities of the cylinder and the tank are separated. Therefore, with further movement of the piston 13, fluid pressure is created in the working cavity of the front brake drive, which is transmitted through pipelines and hoses to the wheel cylinders of the front brakes. It also affects the floating piston 10, which, moving, creates pressure in the rear brake drive. Under increasing fluid pressure in the working cavities, the front sealing rings of the pistons expand and begin to fit more closely to the surface of the cylinder and to the end of the grooves, improving the sealing of the pistons in the cylinder. Under fluid pressure, pistons 2 and 31 of the wheel cylinders of the front and rear brakes are extended, pressing the pads to the brake disc 8 and to the drum 35. The resulting braking torques slow down the rotation of the front and rear wheels. In this case, the load is redistributed along the axes of the car: the load on the front axle increases, on the rear axle it decreases. This causes the rear of the body to rise, i.e. the distance between the rear axle beam and the body increases. In this case, the short arm of the lever 42 is lowered, and the piston 41 of the pressure regulator under fluid pressure begins to descend, compressing the spring 43. At the moment of full braking, the maximum load transfer from the rear axle to the front axle and the greatest body lift occur. The grip of the wheels with the road is deteriorating, the pressure of the torsion lever 42 on the piston 41 is reduced. Due to the larger end area of ​​the piston head, the force from the pressure Pz of the liquid lowers the piston down until the head contacts the seal 37. Further flow of fluid to the wheel cylinders of the rear brakes stops, that is, the braking torque on the rear wheels does not increase, despite the strong pressure on the brake pedal and further increase in pressure P1. Therefore, the rear wheels are not blocked and the car does not skid. When the brake pedal is released, it returns to its original position under the action of the return spring 20, dragging the pusher 16 along with it. rings 11, and through the resulting gap, the working cavities of the main cylinder communicate with the cavities of the reservoir of the main cylinder. Pistons 2 of the front brake are retracted from the pads due to the elasticity of the sealing rings 4, and the pistons 31 of the rear brake - by reducing the coupling springs until they stop against the adjusting eccentrics. If the rear brake drive circuit fails due to its leakage, the piston 10 moves under fluid pressure until it stops in the master cylinder plug, after which the pressure in the front brake drive circuit begins to increase. Due to the free movement of the piston 10, the free travel of the brake pedal increases and only the front brake drive is active. If the front brake drive circuit fails, piston 13 moves forward until it stops against piston 10, after which the rear brake drive circuit begins to operate. The brake pedal free play is also increased. It should be remembered that when increasing the free play of the brake pedal, it is not recommended to repeatedly press the pedal, as this will not accelerate braking, but rather lengthen the brake response time. Continue depressing the pedal all the way and, if necessary, apply the parking brake. If any brake circuit is damaged, the fluid level control lamp lights up, signaling a drop in the fluid level in the reservoir. The parking brake system, through a mechanical drive, acts on the brake mechanisms of the rear wheels. When the lever 25 is fed upwards, after selecting the free play of the lever equal to 45 clicks, the front 38 and rear 37 drive cables are tensioned and the force is transferred to the levers 24 of the manual drive of the pads. When the lever 24 is turned on the pin 28, the force is first transmitted through the expansion bar 27 to the front brake shoe until it is completely pressed against the drum. After that, the lever 24 moves relative to the point of contact with the expansion bar, and its upper arm presses the other shoe against the drum. At the same time, the control lamp in the instrument cluster lights up with a flashing red light. since the stop 42 of the lever moves away from the lamp switch stem and the circuit closes.