Having your long haul truck lose power in the middle of nowhere in winters is the worst nightmare ever. Not performing pre-trip air brake inspection can put you into dangerous situations. In this blog, we’ll cover how to perform a pre-trip inspection along with the downsides of not conducting regular inspection. Let’s talk!
What is an air brake?
Air brakes use compressed air to apply pressure to the brake pads, slowing down or stopping the truck. It is a reliable system that has the ability to handle large, heavy vehicles. Unlike hydraulic brakes, which use fluid, air brakes are less prone to leakage and can be more easily maintained. It consists of:
- Compressor: Generates and supplies compressed air to the system
- Reservoirs: Store the compressed air until it is needed
- Brake Pedal: When pressed, it releases air from the reservoirs to the brakes
- Brake Chambers: Convert the air pressure into mechanical force to apply the brakes
- Slack Adjusters: Maintain the correct distance between the brake shoes and the drum
- Brake Shoes and Drums: Actual parts that create friction to stop the vehicle
How do air brakes work?
When the driver presses the brake pedal, compressed air flows from the reservoirs into the brake chambers. The air pressure pushes the diaphragm in the brake chamber, causing the slack adjusters to move and apply the brake shoes against the brake drum, which slows down or stops the vehicle. When you release the brake pedal, the air to escape from the chambers, and springs return the brake shoes to their original position, ready for the next braking action.
Safety beyond just compliance
Regulatory bodies, such as the Federal Motor Carrier Safety Administration (FMCSA) in the United States and similar organizations in other countries, have made pre-trip inspections for commercial vehicles. Compliance with these regulations is non-negotiable and if you don’t follow the rules, you might have hefty fines and penalties, and even risk your trucking license getting suspended.
Moving to safety…. pre-trip inspection can bring some major issues to the forefront. Some common issues include air leaks, low air pressure, worn out brake pads and drums, and malfunctioning lack adjusters.
Regular inspection protects you and those around you. If you survive an accident, you lose weeks or months of pay because of your health’s recovery or repairing the truck. It gets added to your record, which makes finding new jobs more difficult.
How to perform a pre-trip air brake inspection?
Step 1: Park the vehicle on a leveled surface and engage the parking brakes. Place wheel chocks.
Step 2: Inspect the air compressor. Check for visual inspection first. Then start the engine and listen for any unusual noises coming from the compressor.
Step 3: Start the engine and allow the air compressor to build pressure. It should be around 120-135 psi. Your truck’s dashboard will indicate proper pressure levels
Step 4: Turn off the engine to inspect the air reservoirs. Drain the air tanks by opening the drain valves to remove any moisture and oil buildup. Secure the valves once you’re done.
Step 5: With the engine off, fully apply the service brake pedal and hold it down. Listen for any hissing sounds indicating air leaks in the system.Watch the air pressure gauge. The system should not lose more than 3 psi in one minute for single vehicles or 4 psi for combination vehicles.
Step 6: Inspect each brake chamber for signs of damage, corrosion, or wear.
Step 7: Use a ruler or tape measure to check the pushrod travel distance. The movement should be within the manufacturer’s specified limits, usually less than one inch for manual slack adjusters. If the pushrod travel is too long, adjust the slack adjusters to achieve the correct distance.
Step 8: Visually inspect all brake hoses and lines for cracks, wear, or leaks.
Step 9: Inspect the brake drums for excessive wear or cracks. Check the brake linings for thickness and even wear. Replace them if they are worn beyond the manufacturer’s specifications.
Step 10: Perform a service brake test. Start the engine and release the parking brake. : Drive the vehicle slowly forward and apply the service brakes. The vehicle should stop smoothly without pulling to one side.
Step 11: Perform an emergency brake test. Disconnect the trailer and press the brake pedal. Ensure the tractor protection valve activates and closes, preventing air loss. Reconnect the trailer and drive slowly. Pull the trailer air supply valve to activate the trailer emergency brakes. The trailer should come to a stop.
Step 12: Document any issues or concerns identified during the inspection. Report any problems to the appropriate personnel for further evaluation and repair.
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