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 brakes the car in the parking lot.
The working system is double-circuit with a diagonal connection of the brakes of the front and rear wheels.
One circuit of the hydraulic drive provides the operation of the right front and left rear brakes, the other - the left front and right rear.
If one of the circuits of the service braking system fails, a second circuit is used to stop the vehicle with sufficient efficiency.
A vacuum booster is included in the hydraulic drive.
The vehicle is equipped with anti-lock braking system (ABS).
A parking brake system with a cable drive is installed on the car on the brakes of the rear wheels.
The front wheel brake mechanism is disc, with automatic adjustment of the gap between the pads and the disc, with a floating caliper.
The sliding 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 guide pins installed in the holes in the shoe guide.
The guide pins are greased and protected by rubber boots.
A piston with an O-ring is installed in the cavity of the working cylinder.
The elasticity of this ring maintains an optimal clearance between the pads and the ventilated disc.
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 released, the piston is pulled away from the pad due to the elasticity of the sealing ring, and a small gap forms between the pads and the disc.
The brakes of the left and right front wheels are not interchangeable.
Also non-interchangeable inner brake pads. They differ in the location of the grooves on anti-vibration and anti-squeak steel plastic.
On the inner pads, there are marks - arrows indicating the direction of rotation of the wheel.
If, during installation, the pads are mixed up in places, then 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 camera is connected to the right front and left rear brakes, the second to the left front and right rear.
A reservoir is installed on the main cylinder through rubber connecting bushings, the inner cavity of which is divided by partitions into three compartments.
Each of the two main compartments feeds one of the chambers of the master brake cylinder, and the third compartment feeds the master cylinder of the hydraulic clutch release.
When you press the brake pedal, the pistons of the master brake cylinder begin to move, the working edges of the cuffs overlap the compensation holes, the chambers and the reservoir are disconnected, and the displacement of the brake fluid begins.
A brake fluid level sensor is installed in the reservoir cap.
When the liquid level falls below the permissible level in the instrument cluster, the warning lamp for the malfunctioning state of the brake system lights up.
The flange for connecting to the vacuum brake booster is sealed with a rubber ring.
The vacuum booster installed between the pedal mechanism and the main brake cylinder, when braking due to vacuum in the intake pipe of the engine through the rod and the 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 amplifier with the inlet pipe is made in one piece with a check valve inserted through a rubber grommet into the amplifier housing.
The valve holds 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 gap between the pads and the drum.
The brake pads are driven by one hydraulic slave cylinder with two pistons.
The optimal clearance between the drum and the shoes is maintained by a mechanical adjuster mounted on the spacer bar.
As the shoe pads wear out, the shackle turns the adjuster nut and its threaded tip lengthens to compensate for the increasing clearance between the spacer bar and the front shoe rib.
The brakes of the rear wheels of 4x2 and 4x4 cars are almost the same.
The differences are related only to the design of the brake drums.
On four-wheel drive vehicles, the brake drum is attached to the hub, and 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 mechanism for automatic adjustment of the gap consists of a compound spacer strip of the shoes, a regulator lever and its spring.
It starts to work 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.
With a certain wear on the pads and pressing the brake pedal, 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.
Thus, the gradual lengthening of the spacer bar automatically maintains the gap between the brake drum and the pads.
The wheel cylinders of the rear wheel brakes are the same.
The front brake pads of the rear wheels are the same, but the rear ones are different - they are mirror-symmetrically fitted with non-removable levers for the parking brake drive.
The spacer bar and ratchet nut of the brakes of the left and right wheels (4x4 vehicle) are different.
The ratchet nut and the tip of the left wheel spacer have a right-hand thread, and the ratchet nut and the tip of the right wheel spacer have a left-hand thread.
The levers of the brake adjusters of the left and right wheels are mirror-symmetrical.
The vehicle is equipped with an anti-lock braking system (ABS).
The fluid from the brake master cylinder enters the ABS unit, and from there it is supplied to the brakes 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 on the basis of inductive wheel speed sensor signals.
The front wheel speed sensor is located in the wheel hub assembly - inserted into the hole in the steering knuckle.
The master disk of the front wheel speed sensor is the hub bearing shield, located on one of the two end surfaces of the bearing.
This dark colored washer is made of magnetic material.
On the other end face of the bearing there is a conventional light-colored shielding washer.
The rear wheel speed sensor of a 4x2 car is fixed on the brake shield, and the sensor's master disk is a ring made of magnetic material pressed onto the brake drum shoulder.
The rear wheel speed sensor of a 4x4 car is located in the wheel hub assembly - a knuckle hole is inserted.
When the vehicle is braking, the ABS control unit detects the onset of wheel blocking 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 a second, so you can make sure that the ABS is working by a slight tremor of the brake pedal at the time of braking.
In the event of an ABS malfunction, the braking system remains operational, but the wheels may lock.
In this case, the corresponding health code is written into the memory of the control unit, which is read using special equipment at the service center.
Parking brake drive - manual, mechanical, cable, to the rear wheels.
It consists of a lever, a front cable with an adjusting nut at 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 ends of the cables are connected to the parking brake actuator levers attached to the rear shoes.
During operation (until the rear brake pads are completely worn out), adjustment of the parking brake drive is not required, since the lengthening of the brake spacer bar compensates for the pad wear.
The parking brake actuator must only be adjusted when the cables or the parking brake lever are replaced.
Possible malfunctions of the brake system and methods of correction
- Cause of malfunction
Extended brake pedal travel:
- Leakage of brake fluid from the working brake cylinders
Replace the failed working brake cylinders, rinse and dry the pads, discs and drums
- Air in the brake system.
- Damaged rubber O-rings in the master brake cylinder
Remove air by bleeding the system.
Replace master cylinder
- Damaged rubber hoses of the hydraulic brake
Replace hoses and bleed system.
- Increased runout of the brake disc (more than 0.03 mm)
Grind or replace the disc if the thickness of the brake discs is less than 19.8 mm
Insufficient braking performance:
- Oiling of brake pads lining
Rinse and dry the pads
- Seizure of pistons in the working cylinders
Eliminate the cause of seizure, replace damaged parts
- Complete wear of the brake pads
Replace brake pads
- Overheating of the brakes
Stop immediately and let the brakes cool
- The use of low quality pads
Use original pads or products of firms specializing in the production of brake system parts
- Violation of the tightness of one of the circuits (accompanied by a 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 full stroke and replace damaged parts
- Violation of the adjustment of the protrusion of the rod of the vacuum brake booster
Contact service to adjust the amplifier
- Abnormalities in the anti-lock braking system (ABS)
Contact service to check the anti-lock braking 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 service to adjust the amplifier
- Swelling of the master cylinder rubber seals due to the ingress of gasoline, mineral oils, etc. into the liquid.
Flush and bleed the entire hydraulic drive system, replace rubber parts
- Seizure of the master cylinder pistons
Check and replace the master cylinder if necessary
Braking of one wheel when the pedal is released:
- Break or loosening of the clamping springs of the parking brake pads
Replace the spring
- Sticking of the piston in the working cylinder due to contamination or corrosion of the housing
Replace the slave cylinder and bleed the hydraulic brake system
- Swelling of the working cylinder sealing rings due to the ingress of impurities into the liquid
Replace the slave cylinder and bleed the hydraulic brake
- Violation of the position of the caliper relative to the brake disc when loosening the mounting bolts
Tighten the mounting bolts, replace damaged parts if necessary
- Incorrect adjustment of the parking brake system
Adjust the parking brake system
- Violations in the anti-lock braking system
Call for service to check the anti-lock braking system
Skidding or drifting to the side when braking:
- Seizure of the working cylinder piston
Check and repair piston sticking in cylinder
- A blockage of any tube due to a dent or blockage
Replace or clean tubing
- Dirty or oily discs, drums and brake linings
Clean brake parts
- Wheel alignment angles are violated
Adjust the wheel alignment angles
- Different tire pressures
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 braking system (if it is installed on the car)
Increased effort on the brake pedal when braking:
- Defective vacuum booster
- The hose connecting the vacuum booster and the engine intake pipe is damaged, or its fastening is loose
- Swelling of the rubber seals of the cylinders due to the ingress of gasoline, mineral oils, etc. into the liquid.
Replace cylinders, flush and bleed system
Squeak or vibration of brakes:
- Greasing of friction linings
Scrub the pads with a wire brush using warm water and detergent.
Eliminate the causes of fluid or grease on the brake pads
- Wear of linings or foreign inclusions in them
- Excessive runout or uneven wear (felt by vibration of the brake pedal) of the brake disc
Grind or replace disc if front brake discs are less than 19.8mm thick