BRAKING SYSTEM: FUNCTIONS, CLASSIFICATIONS, ELECTRONIC BRAKE(EBS), BRAKE FLUID
The brake is one of the most important controlling components of vehicle. We have heard about drum brake and disk brake. Drum brake is widely used in the automobile. The brakes are required for stop the vehicle within the smallest possible distance or to slow down the vehicle when we needed. Without the brakes we cannot control the vehicle speed so it is the most important system in automobiles. All brakes are working on same principle by converting the kinetic energy of the vehicle into the heat energy which is dissipated into the automobile.
There are two most important requirement of brakes as follow.
1. The brake must be enough strong to stop the vehicle within a minimum distance in an emergency with safety. The driver should have total control over vehicle during emergency braking and the vehicle must not skid.
2. With prolonged application of brake their effectiveness should not be decreases. These characteristics called antifade characteristics.
FUNCTION OF BRAKING SYSTEM
i. Within the shortest possible time to stop the vehicle.
ii. To aid in controlling speed.
iii. To help turning in crowded place.
iv. To hold the vehicle stationary in the presence of operator after it has been brought into rest.
TYPES OF BRAKES
Brakes is one of the most important elements of automobile. There are many types of brakes available in automobile industries. These are primary brake, Secondary brakes, vacuum brake, air brake, disk brake, drum brake etc. The classification of brakes are as follow.
ACCORDING TO THE PURPOSE:
1. Primary or service brake:
This brake is used when the vehicle is in running condition to stop or slow down the vehicle. This is the main braking system, which is situated in both rear and front wheels of the vehicle.
2. Secondary brakes
Secondary brakes, which is also known as parking brake or emergency brake , are used to keep the vehicle stationary. It is generally operated by hand, so also known as hand brake. The main function of this brake, is to keep the vehicle stationary when it is parked.
ACCORDING TO THE CONSTRUCTION:
1. Drum brake:
In this type of brakes, a drum is attached to the axle hub whereas on the axle casing is mounted a back plate. The back plate is made of pressed steal sheet. It provides support for the expander, anchor and brake shoes. It also protects the drum and shoe assembly from mud and dust. It also known as the torque plate because it absorbed the complete torque reaction of the shoe. Two brake shoes are mounted on back plate with friction linings. On or two retractor spring are used to separate brake shoe from drum when the brakes are not applied. The brake shoe is anchored at one end, whereas on the other ends force is applied by means of some brake actuating mechanism which forces the brake shoe against the revolving drum, so the friction force is generated between drum and the shoe and brake applied.
An adjuster is also provided to compensate for wear of friction lining with use. This brake is widely used in motorcycle and the cars.
2. Disk brake:
Disk brake consists of a cast iron disc bolted to the wheel hub and a stationary housing called caliper. The caliper is connected to some stationary part of the vehicle and it cast in two parts, each part containing a piston. In between each piston and the disc there is a friction pad held in position by retaining pins, springs plates etc. There are arrangements in the caliper for the fluid to enter or leave each housing. There passages are also connected to another one for bleeding. Each cylinder contains a rubber sealing ring between the cylinder and the piston.
When the brakes are applied, hydraulically actuated piston move the friction pads into contact with the disc, applying equal and opposite forces on the later. On releasing the brakes, the rubber sealing rings act as return springs and retract the pistons and the friction pads away from the disc.
BASED ON POWER SOURCE
1. Mechanical Brakes
- It is the type of braking system in which the brake force applied by the driver on the brake pedal is transferred to the final brake drum or disc rotor through the various mechanical linkages like cylindrical rods, fulcrums, springs etc. In order to de accelerate or stop the vehicle.
- Mechanical brakes were used in various old automobile vehicles but they are obsolete now days due to their less effectiveness.
2. Hydraulic Brakes-
- It is the type of braking system in which the brake force applied by the driver on brake pedal is first converted into hydraulic pressure by master cylinder (for reference read article on master cylinder) than this hydraulic pressure from master cylinder is transferred to the final brake drum or disc rotor through brake lines.
- Instead of mechanical linkages, brake fluid is used in hydraulic brakes for the transmission of brake pedal force in order to stop or de accelerates the vehicle.
- Almost all the bikes and cars on the road today are equipped with the hydraulic braking system due to it high effectiveness and high brake force generating capability.
3. Air or Pneumatic Brakes
- It is the types of braking system in which atmospheric air through compressors and valves is used to transmit brake pedal force from brake pedal to the final drum or disc rotor.
- Air brakes are mainly used in heavy vehicles like busses and trucks because hydraulic brakes fails to transmit high brake force through greater distance and also pneumatic brakes generates higher brake force than hydraulic brake which is the need of the heavy vehicle.
- The chances of brake failure is less in case of pneumatic brakes as they are usually equipped with a reserve air tank which comes in action when there is a brake failure due to leakage in brake lines.
- High end cars these days are using air brakes system due to its effectiveness and fail proof ability.
4. Vacuum Brakes-
- It is the conventional type of braking system in which vacuum inside the brake lines causes brake pads to move which in turn finally stops or de accelerate the vehicle.
- Exhauster , main cylinder , brake lines , valves along with disc rotor or drum are the main components that combines together to make a vacuum braking system
- Vacuum brakes were used in old or conventional trains and are replaced with air brakes now days because of its less effectiveness and slow braking.
- Vacuum brakes are cheaper than air brakes but are less safe than air brakes.
5. Magnetic Brakes–
- In this type of braking system, the magnetic field generated by permanent magnets is used to cause the braking of the vehicle.
- It works on the principle that when we pass a magnet through a cooper tube, eddy current is generated and the magnetic field generated by this eddy current provide magnetic braking.
- This is the friction less braking system thus there is less or no wear and tear.
- This is the advanced technology in which no pressure is needed to cause braking.
- The response to the braking in this is quite quick as compared to other braking systems.
6. Electrical Brakes-
It is type of braking used in electric vehicle in which braking is produced using the electrical motors which is the main source of power in electric vehicles, it is further divided into 3 types-
(i) Plugging Brakes-
When the brake pedal is pressed in the electric vehicle equipped with plugging braking, the polarity of the motors changes which in turn reverses the direction of the motor and causes the braking.
(ii) Regenerative Braking-
It is the type of electrical braking in which at the time of braking the motor which is the main power source of the vehicle becomes the generator i.e. when brakes are applied, the power supply to the motor cuts off due to which the mechanical energy from the wheels becomes the rotating force for the motor which in turn converts this mechanical energy into the electric energy which is further stored in the battery.
- Regenerative braking saves the energy and are widely used in today’s electric vehicles.
- Tesla Model-S provides the most effective regenerative braking.
(iii) Dynamic or Rheostat Braking-
It is the type of electrical braking in which resistance provided by the rheostat causes the actual braking, in this type a rheostat is attached to the circuit that provides the resistance to the motor which is responsible for de acceleration or stopping of the vehicle.
ELECTRONIC BRAKING SYSTEM (EBS)
Electronic activation of the EBS braking components reduces response and build-up times in brake cylinders. This in turn reduces braking distance by several meters, which can be decisive in some situations. The integrated ABS function ensures driving stability and steerability throughout the braking procedure.
• Increased braking comfort
• Improved vehicle safety
• Improved brake wear
• Easier maintenance
• Electronic Stability Control (ESC), which independently intervenes to adjust engine and brake controls to reduce rollover, skidding, spinning and jack-knifing
• Adaptive Cruise Control (ACC) interface, with driver alert system that automatically monitors traffic and senses distance from the vehicle in front
• Anti-lock Braking System (ABS) and Differential Slip Control (DSR)
• Automatic Traction Control (ATC)
• Electronic activation of all braking system components
• Retarder and engine brake integration into the service brake application
• Brake force distribution adapts to load distribution
• Brake compatibility between tractor and trailer
• Comfortable deceleration control
• Continuous self-testing via integrated diagnostic and monitoring functions
Brake fluid is a type of hydraulic fluid used in brake applications for automobiles and light trucks. It is used to transfer force under pressure from where it is created through hydraulic lines to the braking mechanism near the wheels. Braking applications produce a lot of heat so brake fluid must have a high boiling point to remain effective and must not freeze under operating conditions. Brake fluid is also designed to protect against corrosion of the system materials it contacts, however, those corrosion inhibitors deplete over time.
Excessive moisture is also an issue. MAP continues to seek additional information from brake fluid manufacturers and other technical experts to identify the point of vaporization that may seriously affect braking efficiency and safety.
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