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This section tells you about air brakes. If you want to drive a truck or bus with air brakes, or pull a trailer with air brakes, you need to read this section. If you want to pull a trailer with air brakes, you also need to read Section 6, Combination Vehicles.
Air brakes use compressed air to make the brakes work. Air brakes are a good and safe way of stopping large and heavy vehicles, but the brakes must be well maintained and used properly.
Air brakes are really three different braking systems: service brake, parking brake, and emergency brake.
The parts of these systems are discussed in greater detail below.
There are many parts to an air brake system. You should know about the parts discussed here.
The air compressor pumps air into the air storage tanks (reservoirs). The air compressor is connected to the engine through gears or a v-belt. The compressor may be air cooled or may be cooled by the engine cooling system. It may have its own oil supply or be lubricated by engine oil. If the compressor has its own oil supply, check the oil level before driving.
The governor controls when the air compressor will pump air into the air storage tanks. When air tank pressure rises to the "cut-out" level (around 125 pounds per-square-inch or "psi"), the governor stops the compressor from pumping air. When the tank pressure falls to the "cut-in" pressure (around 100 psi), the governor allows the compressor to start pumping again.
Air storage tanks are used to hold compressed air. The number and size of air tanks varies among vehicles. The tanks will hold enough air to allow the brakes to be used several times, even if the compressor stops working.
Compressed air usually has some water and some compressor oil in it, which is bad for the air brake system. For example, the water can freeze in cold weather and cause brake failure. The water and oil tend to collect in the bottom of the air tank. Be sure that you drain the air tanks completely.
Each air tank is equipped with a drain valve in the bottom. There are two types:
Automatic air tanks are available with electric heating devices. These help prevent freezing of the automatic drain in cold weather.
The parking brake system:
Air brakes are really three different braking systems: service brake, parking brake, and emergency brake.
Air brakes are really three different systems:
Air brakes are really three different braking systems: service brake, parking brake, and emergency brake.
Which component is used to hold compressed air and will hold enough air to allow the brakes to be used several times, even if the compressor stops working?
Air storage tanks are used to hold compressed air. The number and size of air tanks varies among vehicles. The tanks will hold enough air to allow the brakes to be used several times, even if the compressor stops working.
Why do air tanks have a drain valve?
Compressed air usually has some water and some compressor oil in it, which is bad for the air brake system. For example, the water can freeze in cold weather and cause brake failure. The water and oil tend to collect in the bottom of the air tank. Be sure that you drain the air tanks completely.
Which component controls when the air compressor will pump air into the air storage tanks?
The governor controls when the air compressor will pump air into the air storage tanks. When air tank pressure rises to the "cut-out" level (around 125 pounds per square inch or "psi"), the governor stops the compressor from pumping air. When the tank pressure falls to the "cut-in" pressure (around 100 psi), the governor allows the compressor to start pumping again.
The emergency brake system:
Air brakes are really three different braking systems: service brake, parking brake, and emergency brake.
The service brake system:
Air brakes are really three different braking systems: service brake, parking brake, and emergency brake.
Which component pumps air into the air storage tanks?
The air compressor pumps air into the air storage tanks (reservoirs). The air compressor is connected to the engine through gears or a v-belt. The compressor may be air-cooled or may be cooled by the engine cooling system. It may have its own oil supply or be lubricated by engine oil. If the compressor has its own oil supply, check the oil level before driving.
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