BREAKING SYSTEM

BRAKING SYSTEM

The brake system is the most important system on a vehicle from a safety standpoint. You, as the mechanic, are trusted to do every service and repair operation correctly. When working on a brake system, always keep in mind that a brake system failure could result in a fatal vehicle accident. It is up to you to make sure the vehicle brake system is in perfect operating condition before the vehicle leaves the shop.

ACTUALLY, BRAKES USE FRICTION OF BRAKE SHOES AND DRUMS TO CONVERT KINETIC ENERGY DEVELOPED BY THE VEHICLE INTO HEAT ENERGY.

FUNCTIONS OF BRAKES

       -          To slow down or to stop the vehicle as and when required.

       -          To control the vehicle when the vehicle is rolling down on a slope road down ward.

       -          To travel smoothly and safely even in heavy flow of traffic be controlling the movement of the vehicle.

REQUIREMENT OF AUTOMOBILE BRAKES

       -          The brakes must stop the vehicle within shortest possible distance.

       -          Total control of the vehicle should be there.

       -          decelerate in a controlled repeatable manner

       -          help maintain constant speed down hill

       -          hold vehicle stationary on a flat or on a gradient

TYPES OF BRAKE

      1)      MECHANICAL BRAKES

            -          DRUM BRAKES

            -          DISC BRAKES

      2)      HYDRAULIC BRAKES

      3)      POWER BRAKES

            -          AIR BRAKES

      1)    MECHANICAL BRAKES

1)     Drum Brake

Figure shows the Drum Brake.

Drum brake consist of Brake cylinder (Hydraulic cylinder), Drum, Adjuster mechanism, Brake shoes Emergency brake mechanism, & emergency brake Lever.

Drum Brakes are only Found in rear Of The vehicle typically its bolted with hub of the vehicle so its also rotate with the wheel of the car.

How Drum Brake Works?

When we pressed the brake paddle the master cylinder compressed the brake oil and transfer to the Brake cylinder Through Hydraulic pipe line and the cylinder is filled with oil and it push the piston outside.

After cylinder filled with brake oil the brake shoe is in contact with Brake drum and the Brake shoe resist the Brake drum motion & Brake is applied. during this process the Kinetic energy is convert in to heat energy.

2)     Disc Brake

In a disc brake, the fluid from the master cylinder is forced into a caliper where it presses against a piston. The piston in turn squeezes two brake pads against the disc (rotor), which is attached to wheel, forcing it to slow down or stop.

Each time you stop your car, your brakes convert the kinetic energy to heat generated by the friction between the pads and the disc.

  

       2)    Hydraulic Brake

Hydraulic Brake works on the Principle of Pascals law.

Pascals Law:-  Pascal's law basically states that any pressure applied to a fluid inside a closed system will transmit that pressure equally in all directions throughout the fluid. This law is the basic principle that causes hydraulic power in heavy construction machines to work.

Hydraulics is the use of a liquid under pressure to transfer force or motion, or to increase an applied force. The pressure on a liquid is called HYDRAULIC PRESSURE.

And the brakes which are operated by means of hydraulic pressure are called HYDRAULIC BRAKES. Applied in hydraulic lifts, hydraulic brakes etc.

You see the figure of Hydraulic Brake System.

How Hydraulic brake works?

In a hydraulic brake system, when the brake pedal is pressed, a pushrod exerts force on the piston(s) in the master cylinder, causing fluid from the brake fluid reservoir to flow into a pressure chamber through a compensating port. This results in an increase in the pressure of the entire hydraulic system, forcing fluid through the hydraulic lines toward one or more calipers where it acts upon one or more caliper pistons sealed by one or more seated O-rings (O-ring use to prevent linkages).

The brake caliper pistons then apply force to the brake pads, pushing them against the spinning rotor, and the friction between the pads and the rotor causes a braking torque to be generated, slowing the vehicle. Heat generated by this friction is either dissipated through vents and channels in the rotor or is conducted through the pads.

        3)    Power Brake

1)     Air brake

Air brakes are used in trucks, buses, trailers and semi-trailers.

Air Brake consist of Air compressor, Storage tank, Brake pedal, brake actuator, safety valve, Air filter and dryer, direct collector, brake drum, braking lines, triple valve.

1. Air compressor

Air compressor is the main part of any air brake system it is powered by the engine using belt drives. It compresses the atmospheric air up to the desired pressure and transfers it into the storage tank.

2. Storage tank

It stores the compressed atmospheric air at high pressure. It is also a necessary part of the air brake system because compressed air is responsible for the whole operation. Breaks can be applied several times during running of an automobile so compressor alone is not able to perform this task that’s why air storage reservoir required.

3. Brake pedal

Brake pedal is the input to the brake mechanism. It is operated by the driver inside the automobile. The brake pedal is kind of mechanical linkage which transfers input motion to the further mechanism and initiate the brake application.

4. Brake actuator

Brake actuator is the piston-cylinder arrangement which is directly linked with the brake pedal. When the brake pedal is pressed it creates the pressure in the whole assembly.

5. Safety valve

Safety valve a safety component which is attached to the air storage tank. It prevents the bursting of the tank due to excessive pressure because air compressor works continuously and supplies compressed air into the tank. Air is released by the safety valve when the air pressure reaches a certain value.

6. Air filter and dryer

Air filter and dryer are the two major components which are used before the air enters into the air compressor. As the name implies air filter is used to remove the dust particle from the atmospheric air whereas dryer removes the moisture and humidity from the inlet air. It is necessary that only dry air enters into the air compressor because moisture content will lead to failure of braking system due to the condensation of the water particles.

7. Dirt collector

Dirt collector is the small device used before the triplet valve. It is used to collect the dirt particles separated by the air filter.

8. Brake drums

Brake drum is the parts which execute the brakes. It is the last part of the brake assembly. It is mounted on the tires of the automobiles.

9. Breaking lines

Breaking lines are also known as the supply lines. The transfer of compressed air from the reservoir to brake drum is done by breaking lines only.

10. Triple valve

Triplet valve is responsible for the whole operation in air brakes. To apply and release the brake a continuous apply and releasing mechanism is required which is done by the triple valve. When the brake pedal is pressed it applies the pressure whereas when the pedal is released it releases the pressure immediately.

WORKING

Working of the air brake system is very simple. With the help of above components, we easily understand the working of the air brake system. The working of air brake system is described as follow:

The working of air brakes starts with the air compressor. It is the main component of the whole system. Air compressor directly powered by the engine. It compresses the atmospheric air and then transfers it into the storage tank.

Air firstly passes through the air filter and dryer before entering into the compressor. Air filter removes the dust particles from the air make air pure and dryer removes moisture content from the air.

The main working of the braking system starts when the passenger sitting in the vehicle presses the brake pedal, the pedal is directly attached with the actuators having a piston-cylinder arrangement.

After pressing the pedal piston compresses the air due to this pressure in the assembly increases. The outlet port of the triplet valve is closed this time and inlet port opens after that compressed air from the reservoir enters into the braking lines.

These braking lines directly link with the brake drum which has a piston-cylinder arrangement. As the pressure in the braking lines increases the pistons in the brake drum start moving outwards and apply force on the brake shoes which creates the friction force between the brake shoes and brake drum. This operation stops or slows down the vehicle.

To run the vehicle again releases the brake pedal due to this the outlet port of the triplet valve becomes open and inlet ports become close due to this the air is released from the braking line and the brake shoes between the brake drum come again to their initial position with the application of spring.