Why Do Trucks Use Air Brakes?


Why Do Trucks Use Air Brakes?

Have you ever pulled up to a stoplight beside a big truck and you hear the sound of air releasing? This got me thinking, why do trucks use air brakes?

I did some research to learn a bit more about air brakes and this is what I found.

Why Do Trucks Use Air Brakes?

Brakes on a truck require friction to stop make the vehicle stop. Airbrakes provide tremendous pressure or force to the brakes making for better stopping power on a large heavy truck. Air pressure provides more force and more force creates better stopping power.

An airbrake is a type of frictional brake used in heavy vehicles such as trucks due to their reliability. George Westinghouse made the first air brake. After a successful operation, several modifications and alterations, it was adopted by truck and heavy vehicle manufacturers.

Components of an Air Brake System

  • Compressor

The compressor and the engine are connected by the v-belt or gears. It pumps air into the reservoirs. The engine cooling system may cool it.

The compressor may have its oil supply or lubricated by the engine oil. Before driving, check the level of oil in the air compressor if it’s supplying its oil.

  • Air tank drains

Compressed air is terrible for the air brake system since it usually has some compressor oil and some water. The water can cause brake failure if it freezes during cold weather. The oil and water go to the air tank’s bottom. Ensure that the air tanks are drained thoroughly.

There are automatic air tanks available that prevent freezing of the water since they have heating devices. It allows the drainage of the water entirely, especially during the cold season.

  • Storage tanks

These carry compressed air. Size and number vary depending on the type of vehicle.

  • Safety Valve

It is put in the first storage tank, and the compressor pumps in the air. The safety valve secures the system and the tank from a lot of pressure. The safety valve should not release any air. If it does, there must be a problem, and you should have it fixed.

  • Alcohol Evaporator

The alcohol evaporator helps reduce the potential risk of the water freezing in the meters and other components. Frozen water can damage the brakes.

Perform regular check-ups on the alcohol container and fill it up when needed during cold weather. Drain the air tanks daily to get rid of oil and water.

  • Brake pedal

It is known as the foot valve. Once you push down the pedal, the pressure is applied to the brakes. The harder the force applied on the brake pedal, the more air pressure is applied. It would be best to let up the pedal for the air pressure to reduce and the brakes to be released.

Some air goes out of the system when you release the brakes. It causes air pressure in the storage tanks to reduce. Unnecessary releasing and pressing of the brake pedal can quickly release air out than the air to be replaced by the compressor. The brakes won’t work if the pressure gets too low.

  • Foundation brakes

They are used in every wheel of your truck. S-cam brakes are the most common type of foundation brakes.

  • Supply pressure gauges

They are found in all trucks and are used to connect the air brakes to the air tank. Each half of the system should gauge if your vehicle has a dual air brake system. Rather, two needles in a single meter.

  • Application Pressure Gauge

The brakes fade when you increase application pressure to carry the same speed. You should use the lower gear and slow down. Increased pressure needs can be caused by air leaks, mechanical problems, or brakes out of adjustment.

  • Low Air Pressure Warning

Trucks having air brakes require a low air pressure warning signal. You must see a warning signal when the air pressure drops to 54psi. A red light is used to symbolize the warning signal. In some cases, a buzzer may be switched on.

  • Limiting Valve

Trucks and other vehicles in early 1975 controlled the cab. Typically, power is marked as “slippery” and “normal.” When the command is positioned in the “slippery” spot, the valve divides “normal” pressure into two.

Front wheels are prone to skidding on slippery ground. Several trucks have got front-wheel limiting automatic valves. You cannot control these valves as a driver.

  • Spring brakes

It would be best if you equipped your truck with parking breaks and emergency breaks. Spring brakes apply mechanical force to hold it during leakage of air pressure.

  • Antilock Braking System

Trucks manufactured from March 1997 are built with antilock brakes. The antilock braking system is one that prevents the enclosure of your wheels when applying tight brakes. The yellow antilock braking system malfunction lights are found on the instrumental panel of your truck.

How Do Air Brakes Work In Trucks?

The air brake system pushes the brake shoe lining using compressed air onto the brake drum. It creates friction to slow down the wheel. That air eventually reaches the air brake after being pumped through the air brake lines.

Why Do Trucks Make Hissing Sounds?

Your truck uses compressed air to activate the brake pads, unlike a car, which uses a fluid-like substance. Since the pressure is lower, your vehicle uses large diaphragms. All that comes out is air when your truck is disconnected or hooked up to a trailer.

 How Fast Should Air Pressure Be Built By A Truck?

Air pressure should take 40 seconds or less to increase from 84psi to 100psi. Monitor the air pressure gauge while driving during an increase to ensure proper air system process.

Why Are Dump Trucks So Loud?

Dumb trucks are loud because they are huge, typically use diesel with robust hydraulic systems to compact trash. They also operate large steel trash containers that are very noisy by the way they are constructed.

Why Do Truck Air Brakes Fail?

It may be due to mismatching mechanical components or when more pressure is applied to some brakes than others by the pneumatic system. It may lead to jackknifing and skidding due to locking up of brakes caused by the uneven air distribution.

How Do You Deal With Your Wet Brakes?

  • After driving through water, inspect the brakes by lightly pressing and tapping on them.
  • Brakes may not hold at all or may pull towards one side.
  • Drive slowly in low gear , applying pressure to the brakes ,it dries the brakes.

How Long Does It Take To Stop A Truck Completely?

A truck takes more time to stop than a regular car. It depends on the amount of friction between the road and the wheels, your skill as a truck driver and present road conditions, and the load’s total weight. Your driving skills come in handy at this point.

 What Causes A Truck To Jackknife?

When the trailer hooked on the truck exceeds a 45-degree angle to the tractor, the truck jackknifes. It usually happens when the tractor comes into contact with demanding road conditions such as potholes and icy patches while the tractor is empty.

What Causes Trucks To Shake When Braking?

Shaking is a result of the vibration of braking motors. The brake pad presses the rotors to help slow down your truck. If your rotors lack balance, vibrating tremors occur, and you feel it in the steering wheel and pedal.

Why Do Trucks Use Air Brakes?

 Disadvantages of Air Brakes in Trucks

  • Air brakes are more expensive than other types of braking systems.
  • The compressed air in air brakes results in moisture, which needs to be dried out before it freezes. It increases maintenance costs, especially in the first four years of using your truck.
  • In most states, you need to undertake additional training to drive any vehicle using an air brake system. It might be expensive in addition to acquiring a license that permits you to handle air brake vehicles.
  • Air brake vehicles are problematic, and so is learning about them. It takes a lot of reading and time to understand how they operate.
  • Air brake vehicles require proper knowledge on how to use and maintain them. As a driver, you must perform regular inspections of the various components of the air brake system.
  • High proficiency and particular skill are required when handling air brake system trucks. A mistake will incur a huge loss and cost of repair and replacement. It can even be catastrophic, especially when these large trucks are involved in an accident.
  • Lives may be lost in addition to cargo and other vehicles.

 Can Brake Shudder be Dangerous?

Brake shudder can be dangerous. It could mean that you do not have adequate or equal pressure, which might affect your stopping distance.

Trucks are hefty automobiles that weigh 20 times more than regular cars. Some even carry cars in their storage containers and transport them from one place to another.

Trucks need air brakes to stop well since they are a more advanced braking system. Instead of mechanical brakes, most trucks are installed with air brakes to ensure no physical activation failure. The air brake system is more complicated than your average car’s brake system.

Final Thoughts

The next time you are sitting in your vehicle and you hear a big truck come up beside you and the air pressure in his air brakes release, you will know exactly what is going on!

It’s pretty cool to think this technology was developed for giant trains and was later adapted to large trucks.

John Nelson

You can find John stringing a hammock from the back of his SUV to a tree camping in the outdoors most weekends during warmer weather. John loves the outdoors and the freedom four-wheel-drive vehicles offer.

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