Bus Braking System: Understanding The Mechanics Of Buses

Buses, like heavy trucks, use air brakes due to their efficiency in managing the significant braking demands posed by these large, heavy vehicles. Air brakes use compressed air that presses on a piston and then applies pressure to the brake pad to stop the vehicle. When the driver steps on the brake pedal, it reduces the air pressure from the brakes, thus engaging the calipers again. Air brakes are more complicated and expensive than ordinary hydraulic disk brake systems because they have more components and require many processes when in use.

Air brakes use compressed air to press a piston

Compressed air is used in air brakes because of its high potential energy. This potential energy is stored in the system as compressed air in tanks until it is needed. When the driver presses the brake pedal, the compressed air is released, activating the brakes. The use of compressed air means that the driver does not need to exert much physical force on the brake pedal, which would be difficult, if not impossible, in large, heavy vehicles.

Air brakes are typically used in large, heavy vehicles because they have several advantages over hydraulic brakes, which are used in lighter vehicles. Air brakes do not require hydraulic fluid, which could leak, and there is no limit to the supply of air, so the brake system cannot run out of operating fluid. Air brakes are also easier to attach and detach, and they can be used for accessory applications that hydraulics are not appropriate for, such as air horns and seat adjusters.

Air brakes are used in large, heavy vehicles

Air brakes, or compressed-air-brake systems, use compressed air to press on a piston, which then applies pressure to the brake pads or shoes to slow or stop the vehicle. This is in contrast to hydraulic brake systems, which use hydraulic fluid to transfer pressure from the brake pedal to the brake shoe.

Air brakes also have built-in safety mechanisms. For example, air pressure is used to release the parking/emergency brakes, and a sudden loss of air pressure would result in the immediate application of full spring brake pressure. Additionally, air brakes can still function effectively even with considerable leakage, and the air compressor ensures that there is always enough air pressure for safe vehicle operation.

Air brakes are a type of friction brake

Air brakes work by using compressed air to press on a piston, which then applies pressure to the brake pads or shoes to slow and stop the vehicle. When the driver presses the brake pedal, compressed air stored in the reservoir tanks is released through valves and hoses to the brake chambers. This release of air pressure activates the brakes, causing the brake shoes or pads to engage with the drums or rotors, creating friction and slowing down the vehicle.

The air brake system is divided into two parts: the supply system and the control system. The supply system compresses, stores, and supplies high-pressure air to the control system and other auxiliary systems. The air compressor draws in air from the atmosphere, compresses it, and stores it in high-pressure reservoirs. Most heavy vehicles have a gauge that indicates the availability of air pressure for safe vehicle operation, often with warning tones or lights.

The control system consists of the service brakes, parking brakes, a control pedal, and an air storage tank. The service brakes are used while driving to slow down or stop the vehicle. When the brake pedal is pushed, air is routed under pressure from a supply reservoir to the service brake chamber, causing the brake to engage. When the pedal is released, a return spring in the brake chamber disengages the brake, and the compressed air is released.

Air brakes are generally more expensive than hydraulic disc brake systems due to their complexity and the number of components and processes involved. They also require additional training for drivers to operate and maintain them properly.

Air brakes are safer than hydraulic brakes

Secondly, air brakes default to a position of being stopped. In contrast, if there is a leak in the brake line of a hydraulic system, the fluid pressure can decrease to the point where there is not enough force for the brake pads to create the necessary friction to slow or stop the wheel. This can potentially lead to a dangerous situation where the vehicle is unable to brake. With air brakes, if there is a leak, the air pressure decreases, which actually activates the brakes and brings the vehicle to a safe stop. This is because air brakes use compressed air to activate the brakes, and when the air pressure decreases, the brakes are engaged.

Additionally, air brakes do not rely on a fluid for compression, so they cannot run out of fluid and are not affected by minor leaks. The supply of air is unlimited, which ensures their reliability. This is particularly important for larger vehicles such as buses and trucks, where the braking demands are significantly higher due to their size and weight.

Furthermore, air brakes are easier to maintain than hydraulic brakes. Airline couplings are simpler to attach and detach, and there is no mess from hydraulic fluid. The risk of air getting into the hydraulic fluid is also eliminated, as is the need to bleed the brakes during servicing. Overall, air brakes provide superior safety, reliability, and maintainability compared to hydraulic brakes, making them the preferred choice for heavier vehicles.

Air brakes are more expensive than hydraulic brakes

Air brakes are a critical safety component of diesel vehicles, such as buses and trucks. They are designed to handle the significant braking demands posed by these large, heavy vehicles. Unlike hydraulic brakes, air brakes use compressed air instead of hydraulic fluid to apply the brakes. This makes them more suitable for heavier vehicles as they provide greater stopping power.

While air brakes offer enhanced safety features, they come at a premium price. A truck air brake system can cost approximately $2,500 more than hydraulic brakes due to the extra components required to operate the system. Air dryers, for instance, are necessary to remove moisture from the compressed air, adding to the initial purchase cost.

The higher price tag of air brakes is further justified by their reliability and robustness. In the event of a leak in an air brake line, air pressure decreases, which actually activates the brakes and brings the vehicle to a safe stop. On the other hand, a leak in the brake line of a hydraulic system can lead to a loss of braking power as the fluid pressure may drop below the level required to exert sufficient force on the brake pads.

Additionally, air brakes are preferred in heavier trucks with a gross vehicle weight rating (GVWR) above 26,000 pounds. Hydraulic brakes are typically used on lighter vehicles with a GVWR of up to 26,000 pounds, as their duty cycle is less severe. Therefore, the choice between air and hydraulic brakes depends on the size and specific requirements of the vehicle.

It is worth noting that air brakes require proper maintenance and synchronization of their components to ensure optimal functionality and safety. This includes regular servicing of parts such as the air compressor, reservoir tanks, valves, hoses, brake chambers, and brake shoes or pads.

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