Virtually all of the semis and other heavy-duty work trucks on the road today utilize air brakes. Air brakes have a greater reliability than hydraulic brakes, and they can ensure that you can stop your truck safely every time. Of course, even air brakes can develop problems that reduce roadway safety. Many such problems stem from damage or degradation to system components.
Unfortunately, many operators fail to understand all of the components that make up an air brake system, which can lead to neglect and a higher risk of breakdowns. If you would like to brush up on your knowledge regarding air brakes, keep reading. This article outlines three key things to know about the component known as the air dryer.
1. Air Dryers Protect Against System Contaminants
At the heart of an air brake system lies the compressor, whose job involves pressurizing the air used to power the brakes. Pressurizing air raises its temperature. When this air flows through the air lines leading from the compressor to the storage tank, it cools down again. This cooling process often causes water vapor present in the air to condense.
If this condensation makes it all the way to your supply tank, it can cause serious problems. For one thing, metal components may fall prey to rust and corrosion. In winter, this moisture can also lead to freeze-ups, which can potentially knock out one or more of your brakes altogether. Air dryers protect your system by removing water from the air moving out of the compressor.
In addition, air dryers also remove any oil that manages to leak into the air stream. Oil contamination can also have catastrophic results for downstream air brake components, such as dash valves and brake chamber diaphragms. Oil also contributes to seal degradation, a common cause of air leaks.
2. Air Dryers Have Two Cycles
Whenever your air compressor turns on, the air dryer enters its charge cycle. During this cycle, compressed air routes through a desiccant-filled drying cartridge. First, the air passes through an oil separator, which removes any oil. The rest of the air then flows on through the desiccant, which absorbs any water vapor present in the air stream.
Once the compressor has finished its cycle, the air dryer enters its purge mode. A purge valve located at the bottom of the dryer opens, causing the air dryer’s internal pressure to drop. This change in pressure acts to draw the moisture out of the desiccant beads. The water then flows out of the air dryer through the purge valve.
3. Air Dryer Cartridges Have a Finite Lifespan
By regularly purging condensed water, an air dryer refreshes its desiccant beads, readying them to absorb more vapor. In this manner, the charge and purge cycle can repeat itself over and over. Yet an air dryer does not have an infinite lifespan. As the oil separator fills up, oil begins making its way into the heart of the cartridge.
This oil attaches to the desiccant beads, reducing their ability to bond with water vapor. As a result, the air dryer cartridge gradually loses its effectiveness. For this reason, truck operators must replace their air dryer cartridges regularly. The lifespan of a cartridge varies, with the most important factor being the application of the vehicle.
Generally speaking, the more heavily you use your brakes, the sooner the air dryer wears out. For instance, city refuse trucks usually need to replace their air dryer cartridge about once a year. Linehaul truckers, by contrast, can often get as much as three years out of an air dryer, since long-distance highway travel requires less intensive braking.
Air dryers have a crucial role to play in maintaining the effectiveness and quality of your brakes. For more information about what it takes to keep an air dryer in tip-top shape, contact Godfrey Brake Service.