Rear wheel brakes

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The brake mechanism of back wheels. Brake pads, wheel cylinder 37 and other parts are mounted on shield 8, which is mounted on the flange of the rear axle beam and is the base part of the brake mechanism. At the base of the circular shoulder of the shield, six bosses evenly spaced around the circumference are stamped, which serve as reference points for the rims of 2 brake shoes. A package of plates is installed on the lower forging of the shield on two rivets 25, which form the support for the lower ends of the brake pads. The end plates 30 and 27 limit the lateral displacement of the brake pads, and the plates 28 limit the lateral displacement of the cable 24.


A wheel cylinder 37 is attached to the upper forging of the shield. In the side lug of the cylinder body, in addition to the threaded holes for fastening, there is a central hole for supplying brake fluid and an upper hole for bleeding the brake system. The fitting 40 of the pipeline is screwed into the central hole, and the fitting 41 for bleeding the brakes is screwed into the upper hole.

Two opposed pistons 11 are placed inside the cylinder. Stops 14 are pressed into the outer ends of the pistons, against the grooves of which the upper ends of the ribs of the brake pads rest. The pistons of the wheel cylinder in a non-working state, when there is no brake fluid pressure in the pipelines, are pressed against the brake shoes by a spacer spring 39 through the support cups 38 and sealing rings 12. For the exact position of the spacer spring during assembly, the support cups are pressed onto its ends. The exit of the pistons from the cylinder is protected by rubber cuffs 13, the outer edges of which are thrown over the cylinder flanges, and the inner ones - over the piston necks.

The brake pads of the car 8A3-2103, mounted on the shield 8, are pulled together by the upper 32 and lower 26 springs. The lower ends of the pads rest against the plate 29, and the bushings 20 of the automatic adjusting device rest against the axis 15. The upper coupling spring is longer than the lower one, therefore, to prevent vibrations and knocking while the car is moving, it is pressed against two rubber pads 33. The pads are held from lateral movement by the grooves of the stops 14, guide plate 30 and springs 21, hooked to the jumpers of the ribs of the blocks and to the shield through the ears 22.


The brake pads of VAZ-2101, 2102 cars in the non-working state are pressed by the upper spring until they stop against the adjusting eccentrics 10 and from lateral movement, except for the plate 30 and stops 14, they are held by the racks 7. The rack is held by the cap on the shield 8, and by the shoulders, through the cups 6 and 4 and spring 5 between them, limits the lateral movement of the block. non-rigid (spring) the connection of the brake shoe with the shield allows the shoe to self-adjust at the moment of contact with the surface of the drum 53.

Brake pads are welded. The friction lining 3 is glued to the surface of the rim 2 with a special adhesive BFT-2, and then polished.

The control device installed on each VAZ-2103 brake shoe consists of a steel sleeve 20. two ceramic-metal friction washers 19, a spring 17 and a nut 16. The friction washers are pressed on both sides to the rib of the brake shoe by the force of a spring compressed by a nut screwed onto the sleeve. The nut 16 after screwing up to the stop is stopped from self-unscrewing by rolling the collar of the sleeve 20.

The principle of operation of the control device. The brake shoe with actuation of the hydraulic drive of the brakes, overcoming the resistance of the spring 32 and at the same time choosing the gap between the axle 15 and the sleeve 20, moves all the way into the brake drum.

If the gap between the lining 3 and the drum 53 is greater than the gap between the axle 15 and the sleeve 20 (lining, drum wear), then the shoe, moving all the way into the drum, overcomes the friction force between the rib 1 and the friction washers 19. With the termination of the hydraulic drive, the brake shoe is retracted from the drum by the spring 32 only by the amount of the gap (0.8 mm) between the bushing and the axle, since there is not enough spring force to overcome the friction force in the adjusting device. Thus, the clearance specified by the design between the brake shoe lining and the drum is restored as their rubbing surfaces wear out.


To adjust the gap between linings 3 and drum 53 (VAZ-2101 and 2102) adjusting eccentrics 10 are installed, fixed in the wall of the shield 8 with nuts 9, screwed onto the shanks of the eccentrics with a certain tightening torque, which ensures a constant turning moment of the eccentrics (not less than 0.65 kgf·m). This is done to prevent spontaneous rotation of the eccentric. From self-unscrewing, nuts 9 are welded to the shanks after tightening.

The parking brake includes a mechanical drive from a hand lever 56 located on the floor between the front seats, and a rear wheel brake.

The brake pads are pressed against the drum when the lever 34 and the expander plate 35 are moved. The lever 34 is seated on the pin 36 and, together with the rib of the brake shoe, rests against the groove of the expander bar. On the lower end of the lever, made in the form of a hook, the stirrup 31 of the tip of the steel cable 24 is thrown over. The second end of the cable is connected to the brake mechanism of the other wheel. For protection and support in the mounting brackets and brake shields, both knees of the cable are enclosed in a multilayer sheath of plastic tubes and wire braid. In addition, return springs 23 are put on the ends of the cable, which help the rear cable return to its original position when it is released from force. The rear tip 71 of the shell is attached to the brake shield 8, and the front tip 70 of the shell abuts against the bracket on the bottom of the body.

The rear cable is lubricated with lithium soap grease before assembly and does not require additional lubrication during operation.


The middle part of the rear cable, free from the shell, is thrown over the guide bracket 66, put on the tip 65 of the front cable 63.

The movement of the cable is guided by a plastic roller 64, and the return spring 68 helps the cable to return to its original position when the lever 56 is released.

The parking brake lever is mounted on a bracket 61 and rotates on a roller, at the other end of which a return lever 62 is mounted. The assembly of levers with a roller and bracket is one-piece.

Inside the lever 56, the pawl 59 swings on the axis, which fixes the lever in a predetermined position and is controlled by the button 54, the rod 58 and the spring 55. The pawl engages with the toothed sector 60, which is riveted between the uprights of the bracket 61. When the lever 56 is moved upwards, the pawl is free slides along the gear sector. To return the lever to the lower position, you must press the button 54, thereby releasing the pawl from engagement with the sector.

The degree of tension of the front 63 and rear 24 cables (consequently, the stroke of the lever 56) adjustable by screwing or unscrewing the nut 67 with a lock nut.

When braking a moving car, the load on the axles is redistributed, i.e. the main load is transferred to the front suspension, and the rear suspension, respectively, is unloaded, and the adhesion of the rear wheels to the roadway decreases.

In order to avoid «yuza» rear wheels during braking and, consequently, the possible skidding of the car, a pressure regulator is connected in series to the rear brake hydraulic drive system. Its purpose is to reduce the pressure in the hydraulic drive of the rear wheels, that is, to reduce the braking efficiency while reducing the load on the rear suspension.

The pressure regulator is mounted on a bracket, which is fixed to the bottom of the body on the right side (along the way). The regulator is actuated by a two-armed lever fixed on two supports: one support is on the rear floor panel, the other support is a finger inserted into the ears 52 of the regulator body.

The long arm of the lever is connected through a ladder to the beam of the rear axle. The short arm of the lever rests against the shank 51 of the regulator piston and transmits the oscillatory movement of the rear suspension to the piston.

The swivel joints and lever support do not require maintenance during operation, since the rubber bushings of these joints protect the friction surfaces from ingress of abrasive particles and moisture.

Steel piston 48 divides the regulator cavity into two cavities - upper and lower and is the main part that regulates the bypass of brake fluid from one cavity to another.

The lower cavity is connected to the pipeline coming from the master brake cylinder, and the upper cavity is connected to the pipeline going to the rear brake wheel cylinders.

The exit of the piston rod from the body is sealed with a rubber ring 50 with a spheroidal friction surface. Spring 47, resting against the floating plate 46 (and through it and into the shoulders of the piston), tends to constantly squeeze the piston until it stops with its protrusion into the plug 43.

The rubber seal 45, on which the piston head sits when the regulator cavities are separated, is also of a floating type, but its movement to the piston head is limited by sleeve 44.

At the top (non-working) position of the piston, the brake fluid from one cavity of the regulator passes into another through the gaps between the piston rod, the plate 46 and the seal 45, the piston head, the seal and the sleeve 44 and further along the groove of the plug 43 into the body bore, to the upper hole.