The car is equipped with two independent braking systems: service and parking (Fig. 1)
The first provides braking when the car is moving and has a hydraulic drive, the second brakes the car when parked and has a mechanical drive.
The car uses a service braking system with diagonal separation of circuits, which significantly increases the safety of driving the car.
One hydraulic drive circuit operates the right front and left rear brake mechanisms, the other - the left front and right rear.
If one of the circuits of the service brake system fails, the second circuit is used, ensuring that the car stops with sufficient efficiency.
The hydraulic drive includes: the main brake cylinder 9, the vacuum booster 7, the reservoir 11 of the main cylinder, the pressure regulator 12 of the rear brakes, the brake mechanisms of the front and rear wheels together with the working cylinders and pipelines.
The parking system has a drive to the brake mechanisms of the rear wheels.
In Fig. 2 shows the master cylinder 1 variant.
Possible malfunctions of the brake system and methods of elimination
- Cause of malfunction
Remedy
Increased working stroke of the brake pedal
- Brake fluid leak from the brake cylinders
Replace the failed parts of the brake cylinders, flush and dry the pads, discs and drums
- Air in the brake system
Remove the air by bleeding the system, article - "Replacing the brake fluid"
- Damaged rubber sealing rings in the master brake cylinder
Replace the rings (if the cylinder has a collapsible design) or replace the cylinder assembly
- Damaged rubber hoses of the hydraulic drive brakes
Replace the hoses and bleed the system
- Increased runout of the brake disc (more than 0.15 mm)
Grind or replace the disc if its thickness is less than 9.5 mm
- Fluid leaking through the O-rings of the pressure regulator pusher
Replace the O-rings or the regulator assembly
Insufficient braking efficiency
- Oiling of the brake pad linings
Flush and dry the pads
- Seizure of pistons in brake cylinders
Eliminate the causes of seizure, replace damaged parts
- Complete wear of the brake pad linings
Replace the brake pads
- Overheating of the brake mechanisms
Stop immediately and let the brake mechanisms cool down
- Using pads with inappropriate linings
Use the manufacturer's pads and recommended linings
- Loss of tightness in one of the circuits (accompanied by a failure of the brake pedal)
Replace damaged parts, bleed the system
Incomplete release of all wheels
- No free travel of the brake pedal
Adjust the free travel of the pedal
- The protrusion of the adjusting bolt of the vacuum booster rod relative to the mounting plane of the master cylinder is incorrect
Adjust the protrusion of the adjusting bolt
- Swelling of the rubber seals of the master cylinder due to gasoline, mineral oils and other substances getting into the liquid etc.
Flush and bleed the entire hydraulic system, replace rubber parts
- Jamming of the master cylinder piston
Check and replace the master cylinder if necessary
Brakes one wheel with the pedal released
- Fracture or weakening of the rear brake shoe tension spring
Replace the spring
- Seizure of the piston in the working cylinder due to contamination or corrosion of the housing
Replace the working cylinder
- Swelling of the working cylinder sealing rings due to ingress of foreign impurities
Replace the slave cylinder and bleed the brake hydraulic system
- Violation of the position of the caliper relative to the brake disc when the bolts securing the shoe guide to the steering knuckle are loose
Tighten the mounting bolts, replace damaged parts if necessary
- Incorrect adjustment of the parking brake system
Adjust the parking brake system
Skidding or pulling the car to the side when braking
- Jamming of the piston of the slave cylinder
Check and eliminate jamming of the piston in the cylinder
- Clogging of any steel tube due to a dent or blockage
Replace or clean the tube
- Contamination or oiling of discs, drums and linings
Clean the brake components
- The pressure regulator is faulty
Repair or replace the regulator
- The wheel alignment angles are incorrect
Adjust the wheel alignment angles
- Different tire pressure
Set the correct tire pressure
- One of the brake system circuits is not working (accompanied by a deterioration in braking efficiency)
Replace damaged components and bleed the system
Increased force on the brake pedal when braking
- The vacuum booster is faulty
Replace the booster
- The hose connecting the vacuum booster and the engine intake pipe is damaged or loose
Replace the hose or tighten the clamps that secure it
- Swelling of the rubber cylinder seals due to gasoline, mineral oils, etc. getting into the fluid.
Replace the rubber parts, flush and bleed the system.
Squeaking or vibration of the brakes.
- Weakening of the rear brake shoe tension spring.
Check and replace the tension spring if necessary.
- Ovality of the brake drums.
Bore out the drums.
- Oiling of the friction linings.
Clean the linings with a wire brush, using warm water and detergent. Eliminate the causes of fluid or grease getting on the brake pads
- Wear of the linings or inclusion of foreign bodies in them
Replace the pads
- Excessive runout of the brake disc or its uneven wear (felt by vibration of the brake pedal)
Grind or replace the disc if its thickness is less than 9.5 mm