The crucial components of an Air Brake System include:
The air compressor's pivotal role lies in generating and maintaining the required air pressure. Driven by the vehicle's engine through mechanisms like belts and pulleys or shafts and gears, it pumps air into a reservoir, creating pressurised air. The compressor remains in continuous operation while the engine runs, ensuring a steady supply of compressed air for air brakes and auxiliary systems.
Reservoirs function as pressure-rated tanks for storing compressed air. They house an ample air volume to accommodate multiple brake applications in scenarios such as engine stops or compressor failures. The number and size of reservoirs vary based on factors like brake chamber count, size, and parking brake configuration.
Positioned between the compressor and the wet reservoir, an air dryer aids in moisture removal from the compressed air. It might contain a moisture-absorbent desiccant and oil filter or feature baffles to separate moisture from air.
Acting as a safety measure, the valve prevents reservoir over-pressurisation. If the governor malfunctions and fails to unload the compressor, this spring-loaded valve releases excess air into the atmosphere, its pressure setting determined by the spring's force.
Fig 2: Foot valve
The foot valve draws compressed air from reservoirs for braking purposes. It's operated by the driver's foot and regulates the air delivered to the brakes based on the degree of treadle or brake pedal depression. Releasing the valve facilitates the movement of the air from the service brakes. The foot valve automatically maintains application air pressure when the brakes are applied partially.
Fig 3: Brake Chamber
Brake chambers serve to convert compressed air pressure into mechanical force, engaging the vehicle's brakes. These circular containers house a flexible diaphragm, with air pressure causing the diaphragm to move and apply force against the slack adjuster. Mounted on the axle near the brake-equipped wheel, brake chambers transfer air pressure into mechanical motion.
Fig 4: Brake Assembly
The brake assembly combines the brake chamber and slack adjuster, connected to the backing plate due to steering dynamics. Air pressure moves through an inlet port, pushing the diaphragm and the pushrod. The pushrod connects to a slack adjuster, which then transforms the motion into a twisting motion for the brake camshaft and S-cams. Upon air exhaustion, the return spring in the brake chamber restores the diaphragm and pushrod to their original positions.
All-in-One Pass For All Your ExamsThe working principle of the Air Brake system is elaborated below:
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The below table shows some important differences between air brake and hydraulic brake systems.
Aspect
Air Brake System
Hydraulic Brake System
Use compressed air to apply pressure on brake components.
Employ hydraulic fluid to transmit pressure to brake components.
Hydraulic fluid (brake fluid).
Slightly slower due to air compression and release time.
Faster response due to direct transmission of hydraulic fluid.
Requires periodic checks for air leaks and moisture buildup.
Needs regular fluid checks for leaks and brake fluid condition.
More complex system involving air compressors, reservoirs, valves, etc.
Relatively simpler with fewer components.
Generates less heat during braking.
Generates more heat during braking.
Commonly used in heavy-duty vehicles like trucks, buses, and trains.
Widely used in smaller vehicles like cars and motorcycles.
Less susceptible to brake fading.
More susceptible to brake fading due to heat buildup.
Effective in heavy vehicles and long descents due to less fading.
Effective for everyday driving with less heat-related concerns.
Resistant to fluid contamination issues.
Prone to fluid contamination if the hydraulic fluid is compromised.
Offers a parking brake function even if the air system fails.
Generally relies on a separate mechanical emergency brake.
The advantages encompass the following:
The disadvantages include:
The Air Braking System finds applications in the following:
This blog articulated the details related to Air braking system. We recommend our readers they should appear in the SSC JE Mechanical mock tests and SSC JE ME Previous Years Papers. Also, get enrolled in the AE/JE Mechanical coaching to get a firm grip on the subject.
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An air brake system is a mechanism that utilises compressed air to facilitate efficient deceleration and stopping of vehicles by applying pressure to brake components. This system stands as a pinnacle of safety and efficiency in various vehicles, ranging from automobiles to heavy-duty trucks and trains. With its intricate network of components and valves working in harmony, the air brake system has not only transformed the landscape of transportation but has also played a pivotal role in enhancing road safety and enabling the movement of massive cargoes across vast distances.
This article shall uncover all information related to the Air Brake System. This topic in mechanical engineering is important for your upcoming examinations like SSC JE ME and RRB JE Mechanical Engineering.
Fig 1: Air braking system
An air brake system, also known as a compressed air brake system, functions as a friction brake in vehicles, employing compressed air on a piston to exert the necessary pressure on brake pads for vehicle cessation. These brakes find prominence in sizeable, weighty vehicles, especially those with multiple interconnected trailers like trucks, buses, trailers, semi-trailers, and are additionally integral to railroad trains.
The crucial components of an Air Brake System include:
The air compressor's pivotal role lies in generating and maintaining the required air pressure. Driven by the vehicle's engine through mechanisms like belts and pulleys or shafts and gears, it pumps air into a reservoir, creating pressurised air. The compressor remains in continuous operation while the engine runs, ensuring a steady supply of compressed air for air brakes and auxiliary systems.
Reservoirs function as pressure-rated tanks for storing compressed air. They house an ample air volume to accommodate multiple brake applications in scenarios such as engine stops or compressor failures. The number and size of reservoirs vary based on factors like brake chamber count, size, and parking brake configuration.
Positioned between the compressor and the wet reservoir, an air dryer aids in moisture removal from the compressed air. It might contain a moisture-absorbent desiccant and oil filter or feature baffles to separate moisture from air.
Acting as a safety measure, the valve prevents reservoir over-pressurisation. If the governor malfunctions and fails to unload the compressor, this spring-loaded valve releases excess air into the atmosphere, its pressure setting determined by the spring's force.
Fig 2: Foot valve
The foot valve draws compressed air from reservoirs for braking purposes. It's operated by the driver's foot and regulates the air delivered to the brakes based on the degree of treadle or brake pedal depression. Releasing the valve facilitates the movement of the air from the service brakes. The foot valve automatically maintains application air pressure when the brakes are applied partially.
Fig 3: Brake Chamber
Brake chambers serve to convert compressed air pressure into mechanical force, engaging the vehicle's brakes. These circular containers house a flexible diaphragm, with air pressure causing the diaphragm to move and apply force against the slack adjuster. Mounted on the axle near the brake-equipped wheel, brake chambers transfer air pressure into mechanical motion.
Fig 4: Brake Assembly
The brake assembly combines the brake chamber and slack adjuster, connected to the backing plate due to steering dynamics. Air pressure moves through an inlet port, pushing the diaphragm and the pushrod. The pushrod connects to a slack adjuster, which then transforms the motion into a twisting motion for the brake camshaft and S-cams. Upon air exhaustion, the return spring in the brake chamber restores the diaphragm and pushrod to their original positions.
The working principle of the Air Brake system is elaborated below:
The below table shows some important differences between air brake and hydraulic brake systems.
Aspect
Air Brake System
Hydraulic Brake System
Use compressed air to apply pressure on brake components.
Employ hydraulic fluid to transmit pressure to brake components.
Hydraulic fluid (brake fluid).
Slightly slower due to air compression and release time.
Faster response due to direct transmission of hydraulic fluid.
Requires periodic checks for air leaks and moisture buildup.
Needs regular fluid checks for leaks and brake fluid condition.
More complex system involving air compressors, reservoirs, valves, etc.
Relatively simpler with fewer components.
Generates less heat during braking.
Generates more heat during braking.
Commonly used in heavy-duty vehicles like trucks, buses, and trains.
Widely used in smaller vehicles like cars and motorcycles.
Less susceptible to brake fading.
More susceptible to brake fading due to heat buildup.
Effective in heavy vehicles and long descents due to less fading.
Effective for everyday driving with less heat-related concerns.
Resistant to fluid contamination issues.
Prone to fluid contamination if the hydraulic fluid is compromised.
Offers a parking brake function even if the air system fails.
Generally relies on a separate mechanical emergency brake.
The advantages encompass the following:
The disadvantages include:
The Air Braking System finds applications in the following:
This blog articulated the details related to Air braking system. We recommend our readers they should appear in the SSC JE Mechanical mock tests and SSC JE ME Previous Years Papers. Also, get enrolled in the AE/JE Mechanical coaching to get a firm grip on the subject.
Download the Testbook app now to unravel all the exam-oriented study material that you need for your upcoming examinations.
More Articles for Mechanical EngineeringAir brakes work by using compressed air to apply pressure on brake components, converting pneumatic energy into mechanical force to slow down or stop vehicles.
The five basic components of an air brake system are the compressor, reservoirs, valves, brake chambers, and brake shoes or pads.
The different types of air brake systems include the straight air system, the dual air brake system, and the air-over-hydraulic brake system.
Air brakes are commonly used in heavy vehicles such as trucks, buses, trailers, trains, and some larger recreational vehicles.
Disadvantages of air brakes include complexity, potential for fading under prolonged use, maintenance requirements.
