Getting To Know Your Air System: Air Compressors

How Semi-Truck Air Compressors Contribute to Stopping the Vehicle

The air compressor in your semi-truck's braking system, is one of the most important components in making sure you can safely control your vehicle. About braking systems in general, there is a lot to keep track of when you are making your regular inspections and the air compressor is integral. To help you learn a little more about the air compressor in your heavy-duty truck, our team has put together the following article. Read on to learn more about your commercial vehicle's air compressor!

What is a Semi-Truck Air Compressor?

The main purpose of the air compressor in your semi-truck is to make sure compressed air in the braking and air suspension system is supplied properly. These kinds of air compressors are activated by your truck's engine. The compressor unit builds up air for the suspension, auxiliary components, and air brake system. Dependent on the model specified in your truck, the compressor will draw in air that has been filtered in one of two ways: naturally aspirated at atmospheric pressure from the air cleaner, or already at increased pressure from the turbocharger in your engine.

Your truck's air brake system needs a continuous supply of compressed air to function properly. If the pressure exceeds the maximum allotted pressure or dips below the minimum allotted pressure setting, the system will not work as intended. Pressure in the air supply reservoirs is monitored by a governor that determines when the compressor needs to pump air into the system.

How Does a Semi-Truck Air Compressor Work?

All air compressors have a component called a governor. The governor is responsible for monitoring the air pressure that is in the reservoirs at any given time. It is also the piece of the system that lets the compressor know when it needs to pump air. When the system has enough air, the compressor will turn over. When air pressure in the service reservoir dips to the preset minimum of the governor, the governor restarts the compressor building air. It then cycles the air dryer back to air drying mode. As a part of the system's process, air from the atmosphere is compressed and, as a result, the water vapor taken from the air travels into the air system.

What is the Difference Between a Loaded and Unloaded Air Compressor?

During the Air Build Cycle, a compressor that has compressed air that is ready to be pumped into the air system is referred to as "running loaded." When the system has enough air in it, the compressor can turn over without building pressure. This is called "running unloaded." When the air pressure surpasses the preset setting, the governor activates the unloader mechanism which keeps the compressor from building air. This also kickstarts the air dryer's purge function.

What are Some Common Signs of a Bad Air Compressor?

There are several ways to determine whether your air compressor is failing or bad, and it's important to know what they are when you are making your regular checks. Here are a few signs you can look out for when you are looking to see if you need to replace your air compressor:

1. Diesel air brake compressor drive failure.

2. Compressor doesn't build to at least 120psi.

3. Compressor won't build air pressure with the governor removed.

If you are experiencing any of the issues listed above, then you will definitely want to consider having a qualified mechanic diagnose the issue and replace the air compressor if necessary.

Read More About Air Systems

If you are interested in learning more about the air system in your semi-truck, then you've come to the right place. To help you learn as much as possible, our expert team of trucking industry specialists have put together the list of articles below. Click on any of the links below to read more about air systems and the role they play in your semi-truck's overall health.

· Getting to Know Your Air System

· Getting to Know Your Air System: Air Tanks

· Getting to Know Your Air System: Air Dryers

· Getting To Know Your Air System: Gladhands

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