Tractor trailer air systems are crucial for the performance of heavy trucks. They are made up of many moving parts and control more than just braking; they are also used to operate automated manual transmissions (AMTs) and some emission control components.

They even work to protect freight and driver comfort through air suspension and air seat control. So regular inspections and preventive maintenance are key to their performance. In addition, seasonal inspections such as spring and fall get your truck’s air systems ready for extreme operating conditions, namely summer and winter severe temperatures.



Story Time

One small fleet driver we spoke with from Canada told us of an experience he had the day after the truck he was assigned to underwent its annual commercial motor vehicle (CMV) inspection by the truck’s dealer.

“That same day I left Southern Ontario feeling great about the inspection that found only minor defects that were immediately corrected. That was a good day. The next day wasn’t but it could have been much worse.

“I was dropping my speed and braking on an off ramp at Jonesboro, Arkansas when the low air alarm buzzed angrily. One glance at the air pressure gauges showed the needles falling quickly. Fortunately I had slowed enough that there was not a really harsh spring brake application and stopped without further incident. 

“After a delay of several hours the truck was repaired and I was back on my way with the fleet several hundred dollars lighter. Turns out the item that was not found in the inspection was a rubber brake air line on the tractor that was actually rubbing on the spinning driveshaft and finally punctured.”

Inspections are supposed to find any unsafe condition. This one did not and it could have led to a catastrophe. That dealer shop missed an easy opportunity to solidify a customer relationship and avoid what could have been much worse. Thank goodness for secondary braking systems.


Springtime Inspect can Reveal Winter’s Harshness 

So start in spring by inspecting the entire air system. Look and listen for any obvious air leaks. Check the compressor and all valves for signs of oil leaking or other contaminants. Look at all air lines for signs of oil, moisture or damage due to chafing beginning at the treadle valve and working your way back. Also watch for any sign of damage throughout the system. Remove any debris. Make sure all connections are secure.

Drain the air tanks and watch for moisture, the enemy of the air system. In winter the system takes in dense air that is heated by the truck’s engine and air compressor. When the air cools and travels down the various systems it condenses, depositing moisture into the system. That moisture can freeze and block valves causing failures.


Air Dryer Checks

Over winter the air dryer that is designed to remove moisture can be subject to road chemicals and debris that can result in damage to seals and valves. It’s very important to inspect and test its operation when running your system checks. Make sure the compressor and governor cycle correctly and build pressure according to regulations of all jurisdictions.

Most manufacturers of air dryers recommend changing the dryer cartridge at least annually to protect your entire air system components. Many fleets agree that changing the cartridge should be performed in the fall to prepare for winter. Also inspect and perform any necessary maintenance at that time as well.

Before replacing any component it’s a good idea to deplete the air pressure in the system to avoid injury from debris blown at you. Always wear safety glasses. Pressurized air is only your friend when it’s applying the brakes.


Daily Driver Inspections

Educate your drivers on how to include air system checks in their pre-trip inspections. Inspections and maintenance of the air system can prevent expensive breakdowns that cost the fleet far more downtime than regular maintenance. It also saves lives.

Create a checklist for your drivers and techs with maintenance management software that will enable you to provide PMs and inspection reports digitally. At Bright Order we can help with that.

Regular inspections and maintenance are the keys to extending the life of your air system components. We hope these insights inspire you to become proactive in your fleet’s air system maintenance. Mom and Pop repair shops can find opportunity in air system maintenance programs. Truck safely and confidently!