Renault Duster is equipped with two independent braking systems: working and parking
The first, equipped with a hydraulic drive with a vacuum booster, provides braking when the car is moving, the second slows down the car in the parking lot.
Dual-circuit working system with a diagonal connection of the brake mechanisms of the front and rear wheels.
One hydraulic circuit provides the right front and left rear brakes, the other - the left front and right rear.
If one of the circuits of the service brake system fails, the second circuit is used to stop the car with sufficient efficiency.
A vacuum booster is included in the hydraulic drive.
The car is equipped with anti-lock braking system (ABS).
A cable-operated parking brake system is installed on the car on the rear wheel brakes.
The brake mechanism of the front wheel is disc, with automatic adjustment of the gap between the pads and the disc, with a floating caliper.
The moving bracket is formed by a caliper with a single-piston working cylinder.
The shoe guide is bolted to the steering knuckle.
The movable bracket is bolted to the guide pins installed in the holes of the shoe guide.
The guide pins are lubricated with grease and protected with rubber boots.
A piston with a sealing ring is installed in the cavity of the working cylinder.
Due to the elasticity of this ring, the optimal clearance between the pads and the ventilated disc is maintained.
When braking, the piston, under the influence of fluid pressure, presses the inner pad against the disc, as a result of the reaction force, the caliper moves on the fingers and the outer pad is also pressed against the disc, while the pressing force of the pads is the same.
When releasing the piston, due to the elasticity of the sealing ring, it is removed from the pad, a small gap forms between the pads and the disc.
The brake mechanisms of the left and right front wheels are not interchangeable.
Also non-interchangeable internal brake pads. They differ in the location of the recesses on the anti-vibration and anti-creak steel plastic.
The inner pads are marked with arrows indicating the direction of rotation of the wheel.
If you mix up the pads during installation, they will creak when braking.
The main brake cylinder of the "tandem" type of the hydraulic brake drive is installed in the engine compartment directly on the vacuum brake booster.
It consists of two separate chambers connected to independent hydraulic circuits.
The first chamber is connected to the right front and left rear brakes, the second to the left front and right rear.
A tank is installed on the main cylinder through rubber connecting bushings, the internal cavity of which is divided into three compartments by partitions.
Each of the two main compartments feeds one of the chambers of the master brake cylinder, and the third the compartment feeds the master cylinder of the hydraulic clutch release.
When you press the brake pedal, the pistons of the main brake cylinder begin to move, the working edges of the cuffs block the compensation holes, the chambers and the reservoir are separated, and the displacement of the brake fluid begins.
A brake fluid level sensor is installed in the reservoir cap.
If the fluid level falls below the permissible level, the warning light for a malfunctioning brake system lights up in the instrument cluster.
The flange for connection to the vacuum brake booster is sealed with a rubber ring.
A vacuum booster installed between the pedal mechanism and the main brake cylinder, when braking due to rarefaction in the engine intake pipe through the rod and piston of the first chamber of the main cylinder, creates an additional force proportional to the force from the pedal.
The hose connecting the vacuum booster to the intake pipe is made in one piece with a check valve inserted through a rubber bushing into the booster housing.
The valve retains the vacuum in the booster when it falls in the intake pipe and prevents the air-fuel mixture from entering the vacuum booster.
Rear wheel brake drum with automatic adjustment of the clearance between the pads and the drum.
The brake pads are actuated by a single hydraulic working cylinder with two pistons.
The optimal clearance between the drum and the shoes is maintained by a mechanical regulator mounted on the spacer bar.
As the lining of the pads wears out, the earring turns the adjuster nut and its threaded tip lengthens, compensating for the increasing gap between the spacer bar and the rib of the front pad.
The brake mechanisms of the rear wheels of 4x2 and 4x4 cars are almost the same.
The differences are only related to the design of the brake drums.
On 4WD vehicles the brake drum is attached to the hub, while on front wheel drive vehicles the brake drum is itself part of the rear wheel bearing assembly and the bearing is pressed into it.
The automatic clearance adjustment mechanism consists of a composite pad spacer bar, adjuster lever and its spring.
It starts working when the gap between the pads and the brake drum increases.
When the brake pedal is pressed, under the action of the pistons of the wheel cylinder, the pads begin to diverge and press against the drum, while the protrusion of the regulator lever moves along the cavity between the teeth of the ratchet nut.
At a certain amount of pad wear and the brake pedal is depressed, the adjuster lever has enough travel to turn the ratchet nut one tooth, thereby increasing the length of the spacer bar and at the same time reducing the gap between the pads and the drum.
In this way, the gradual lengthening of the spacer bar automatically maintains the clearance between the brake drum and the shoes.
The wheel cylinders of the brake mechanisms of the rear wheels are the same.
The front pads of the brake mechanisms of the rear wheels are the same, while the rear ones are different - they are mirror-symmetrically equipped with non-removable parking brake levers.
The spacer bar and ratchet nut of the brakes of the left and right wheels (4x4 vehicle) are different.
The ratchet nut and lug of the left wheel spacer bar are right hand threaded, while the ratchet nut and lug of the right wheel spacer bar are left hand threads.
The levers of the brake mechanisms of the left and right wheels are mirror-symmetrical.
The car is equipped with an anti-lock braking system (ABS).
The fluid from the master brake cylinder enters the ABS unit, and from there it is supplied to the brake mechanisms of all wheels.
The ABS unit, mounted in the engine compartment on the right side member near the bulkhead, consists of a hydraulic unit, a modulator, a pump and a control unit.
The ABS operates depending on the signals from the inductive type wheel speed sensors.
The front wheel speed sensor is located in the wheel hub - inserted into the hole in the steering knuckle.
The drive disk of the front wheel speed sensor is a protective washer of the hub bearing, located on one of the two end surfaces of the bearing.
This dark colored puck is made of magnetic material.
On the other end surface of the bearing there is a regular light-colored shield.
The rear wheel speed sensor of a 4x2 vehicle is mounted on the brake shield, and the sensor drive is a ring made of magnetic material pressed onto the shoulder of the brake drum.
The rear wheel speed sensor of a 4x4 car is located in the wheel hub assembly - a fist hole is inserted.
When the vehicle is braked, the ABS control unit detects the start of wheel lockup and opens the corresponding modulator solenoid valve to release the pressure of the working fluid in the channel.
The valve opens and closes several times per second, so you can verify that the ABS is working by the slight vibration of the brake pedal at the time of braking.
If an ABS malfunction occurs, the braking system remains operational, but the wheels may lock.
In this case, the appropriate fault code is written to the memory of the control unit, which is read using special equipment in the service center.
Parking brake drive - manual, mechanical, cable, on the rear wheels.
It consists of a lever, a front cable with an adjusting nut on its tip, an equalizer, two rear cables and levers in the rear wheel brakes.
The parking brake lever, fixed between the front seats on the floor tunnel, is connected to the front cable.
An equalizer is attached to the rear end of the front cable, into the holes of which the front ends of the rear cables are inserted.
The rear cable ends are connected to the parking brake levers attached to the rear shoes.
During operation (until the rear brake pads are completely worn out), adjustment of the parking brake actuator is not required, since the lengthening of the brake spacer bar compensates for the wear of the pads.
The parking brake actuator only needs to be adjusted if the cables or the parking brake lever have been replaced.
Possible malfunctions of the brake system and methods of correction
- - Cause of failure
Remedy
Increased brake pedal travel:
- - Leakage of brake fluid from working brake cylinders
Replace failed working brake cylinders, wash and dry pads, discs and drums
- - Air in the brake system.
- - Damaged rubber o-rings in the brake master cylinder
Remove air by bleeding the system.
Replace master cylinder
- - Rubber brake hoses damaged
Replace the hoses and bleed the system.
- - Increased runout of the brake disc (more than 0.03 mm)
Grind or replace the disc if the thickness of the braked discs on the front of the wheels is less than 19.8 mm
Insufficient braking performance:
- - Lubrication of linings of brake pads
Rinse and dry pads
- - Jamming of pistons in working cylinders
Remove causes of jamming, replace damaged parts
- - Complete wear of the brake pads
Replace brake pads
- - Overheating of the brakes
Stop immediately and let the brakes cool down
- - Use of low quality pads
Use original pads or products from companies specializing in the production of brake system parts
- - Violation of the tightness of one of the circuits (accompanied by the failure of the brake pedal)
Replace damaged parts, bleed the system
- - Violation of the position of the brake pedal
Determine the cause of the increase in total travel and replace damaged parts
- - Violation of the adjustment of the protrusion of the rod of the vacuum brake booster
Contact the service for regulation Amplifier settings
- - Violations in the operation of the anti-lock braking system (ABS)
Contact the service to check the anti-lock brake system
- - Incomplete release of all wheels
Replace the brake master cylinder
- - There is no free play of the brake pedal
- - Increased protrusion of the vacuum brake booster rod
Contact the service to adjust the amplifier
- - Swelling of the rubber seals of the main cylinder due to the ingress of gasoline, mineral oils, etc. into the liquid.
Flush and bleed the entire hydraulic drive system, replace rubber parts
- - Jamming of master cylinder pistons
Check and if necessary replace the master cylinder
Braking one wheel with the pedal released:
- - Kink or weakening of the coupling springs of the parking brake pads
Replace the spring
- - Seizure of the piston in the working cylinder due to contamination or corrosion of the body
Replace the slave cylinder and bleed the hydraulic brake system
- - Swelling of the sealing rings of the working cylinder due to foreign impurities entering the liquid
Replace the slave cylinder and bleed the hydraulic brake
- - Violation of the position of the caliper relative to the brake disc when the fastening bolts are loosened
Tighten the mounting bolts, replace damaged parts if necessary
- - Incorrect adjustment of the parking brake system
Adjust the parking brake
- - Violations in the operation of the anti-lock braking system
Contact the service to check the anti-lock brake system
Sliding or pulling the car to the side when braking:
- Jamming of the piston of the working cylinder
Check and fix piston stuck in cylinder
- Clogging of a tube due to a dent or blockage
Replace or clean tube
- Contamination or oiling of discs, drums and brake pads
Clean the brake parts
- Violated wheel alignment
Adjust wheel alignment
- Different tire pressure
Set the required tire pressure
- One of the circuits of the brake system does not work (accompanied by a decrease in braking efficiency)
Replace damaged parts and bleed the system.
If this does not lead to the desired result, contact the service to check the anti-lock brake system (if installed on the car)
Increased brake pedal force when braking:
- Faulty vacuum booster
Replace amplifier
- The hose connecting the vacuum booster and the engine intake pipe is damaged, or its fastening is loose
Replace hose
- Swelling of rubber cylinder seals due to the ingress of gasoline, mineral oils, etc. into the liquid.
Replace cylinders, flush and bleed the system
Squeak or vibration of the brakes:
- Lubrication of friction linings
Brush the pads with a wire brush using warm water and detergent.
Remove causes of fluid or grease on brake pads
- Wear of linings or foreign inclusions in them
Replace pads
- Excessive runout or uneven wear (felt by the vibration of the brake pedal) of the brake disc
Grind or replace the disc if the thickness of the front brake discs is less than 19.8 mm
