Automobile/Automotive Braking System

  Automobile Braking System

An automobile braking system is a mechanical device that works at hydraulic pressure using brake fluid under pressure to the brake network in each wheel in light-duty vehicles. In modern vehicles power assist braking systems for the sake of safety and convenience also less force effort for the driver. There are several power resources used for more effective braking these are main sources engine vacuum, air, engine exhaust gases, regenerative braking and electric braking. In heavy-duty vehicles, air braking is most commonly used in trucks and buses, along with an Antilock braking system (ABS) in both heavy-duty and light-duty vehicles.

Purpose and function of Braking system:

Automobile brake action may be defined as the which stop any motion. Brakes are applied to slow down or stop the moving car or any vehicle.

The function of the brake is to reduce the speed to stop moving vehicles within a minimum possible time and a minimum possible distance and hold the vehicle.

How does the automobile brake function?

When the foot pedal is pressed, the brake fluid in the master cylinder is forced through pipelines to the individual wheel cylinder or calliper unit. The movement of the brake fluid in the wheel cylinder or calliper operates the expander mechanism to move the brake shoes or pads against the brake drum or disc. The friction between the two-part slow or stop the rotating part and the wheel slow and stop the vehicle.

The construction of automobile braking system:

Generally two types of construction of automotive braking system.

• Mechanical Drum Brake 

• Disc Brake

 Drum Brake Construction 

A brake in which curve brake shoes press against the inner circumference of the metal drum and control the speed of the vehicle or lock the wheel, by rubbing against the wheel drum to produce the braking action.

Disc Brake Construction

The disc brake has a metal disc or rotor instead of drums. It uses a pair of flat brake pads, that are forced against the rotating disc to be produced braking. The pads are held in a calliper the straddle the disc the calliper has a piston with a seal and dust boot for each. During braking hydraulic pressures behind each piston in pushes it outward. This force the pads in the contact with the disc, the resulting frictional contact slow and stop the disc and wheel.

How does disc brake function?

In a disc brake, a housing for piston and brake pads, connecting to the hydraulic system hold the brake pads so that straddles the disc. A disc brake consists of a rotating disc and two friction pads which are actuated by four hydraulic wheel pistons contained in two halves of an assembly called a calliper.

Comparison of disc and drum construction types of brakes:

In the case of the disc, brake pads surfaces are directly exposed to the atmosphere air whereas in the drum brake.

Friction pads in the case of the disc brakes are flat as compared to curved friction lining in the case of the drum brake.

Disc brakes less weight than conventional drum system.

Disc brakes have comparatively better anti-fade characteristics.

Compared to the drum type, the disc brake are simple in design.

It is very easy to replace the friction pads when required, compared to the drum type.

The total frictional area of pads in disc brakes is less as compared with the conventional drum brakes 

The major advantage of a disc brake is its resistance to fading and its tendency to remain cooler even after repeated application. 

The main components of the automobile braking system  in modern vehicles:

• Brake Tandem master cylinder

• Wheel cylinder / Calliper unit

• Brake shoes / Brake pads

• Brake Drum / Disc ( Rotor)

• Brake pedal and brake lines and pipes 

Type of automobile braking system:

In an automobile generally two main brake applications in the vehicles. One is a hand brake is also called parking or emergency brake, it employs applies the rear brake which is used during parking and when stopping and starting a car on slop and when parking. So that the brake may remain applied indefinitely. The parking brake is operated by a hand lever. Another foot brake which is operated by the foot its main service brake is used for a stop or slow down on the vehicle.

In the main service, foot brakes have a large variety of braking used in vehicles.

• Mechanical brake ( using it on the older days).

• Hydraulic brake brake

• Power brake Vacuum assists brake (Servo brake) 

• Air braking system 

• Antilock braking system (ABS)

• Exhaust braking

In earlier automobiles had been the use of mechanically brakes linkage with cables and wires work on it. Hydraulic brakes system working and function it mention on above. Nowadays in all modern vehicle brake, hydraulic systems with power assists from several resources like a vacuum, air, exhaust electric for the light brake pedal force is required.

What is a Power brake?

A service brake system, most vehicles have power-assisted braking or power only relatively light pedal force is required to slow or stop the vehicle. The assist is provided by either a hydraulic brake booster or a vacuum brake booster. Both types allow normal (unassisted) braking if the engine is off or if the booster fails however, the driver must then push hard on the brake pedal. Brake operated by power other than physical effort applied at brake pedal is known as power brake. The power may be exerted by air pressure, engine vacuum or electrical energy.

Vacuum-assisted power brake:

Nowadays more vehicle has power in which only a relatively light pedal force is required to break the car light motor car segment vehicles. When the brake pedal is operated a vacuum-operated booster supplies most of the force for pushing the piston into the master cylinder. The vacuum comes from the engine intake (inlet) manifold, by another device, a vacuum pump at attached to the engine which develops the required amount of vacuum for operating the vacuum booster.

Air Braking System :

Air brakes are much more powerful than the hydraulic braking system and that is the reason they are exclusively used in heavy vehicles. An air braking system that uses compressed air to supply the force required to apply the brake. In this system, compressed air is used to help the driver operate the brake with ease. Apart from braking, the compressed air from the reservoir can be used for tyres inflation, windscreen wiper, horn and many other accessories. However air brake involves relatively, more parts besides the air compressor using a contained amount of engine power. The most commonly used air braking system is trucks, buses and another heavy-duty vehicles.

Anti-lock Braking System (ABS) :

Anti-lock braking system (ABS) installed usual set up with service brake to prevent wheel lock-up during braking especially when vehicle facing wet and slippery road condition. The antilock braking system consists of wheel speed sensors to detect incidents wheel locking and ABS modules, through its work on the braking mechanism. During braking application, ABS automatically reduced the pressure on the fluid at each wheel that an about to lock. This provides the most effective braking.

Exhaust Brake System :

An exhaust brake system is a supplementary braking system it helps service brakes for slowdown the heavy-duty diesel engine vehicles when the vehicle is driving on slop hill or downhill road situations.

How does the exhaust brake work?

The exhaust brake is used for additional safety and smoother engine operation for loaded or unloaded conditions of the commercial heavy-duty diesel engine vehicles. It kind of butterfly valve located on the outer part of the turbocharged connected with the exhaust manifold. when the vehicle run into the downhill or slope road condition in a particular gear without acceleration, that butterfly valve partially closes so that the engine exhaust gas does not completely escape from the tailpipe. Exhaust gases create backpressure into the engine cylinders. In resulting engine slow rpm and it controls the engine overruns also prevent heat resistance on the brake drums in the air brakes, this retards the speed of the engine which created a mechanical slowdown through transmission into the rear wheels.

Regenerative Braking System:

The regenerative braking system is only used for hybrid and electric vehicles.  Regenerative braking is the recovery of kinetic energy during braking. In the conventional braking vehicle, a large amount of kinetic energy is converted during friction braking into heat and emitted unused into the vehicle. A conventional hydraulic braking system means using the friction created between the brake drum and shoe or brake pad and disc, to convert vehicle kinetic energy into heat that is dispelled into the atmosphere and the vehicle slows. vehicles use an electric motor to recuperate at least a portion of kinetic energy for reuse.

How does regenerative braking function?

In the regenerative braking system, the electric motor takes from the battery to rotates wheels, which developed kinetic energy when the brakes are applied with the help electric generator or motor in the form of kinetic to propel the vehicle. This electric motor or generator instead of consuming electricity, motor producing it and uses the vehicle in the form of energy and then stored it in the battery. So that regenerative braking converts kinetic energy into electricity for further use, it is also able to slow the vehicle in the same way as a conventional braking system.

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