A semi-truck’s air brake system is far more complex than the hydraulic brakes used in passenger vehicles. When air brakes fail, the massive size and weight of a fully loaded 18-wheeler can easily turn a routine stop into a catastrophic crash. Federal Motor Carrier Safety Administration (FMCSA) data consistently shows brake-related issues among the leading vehicle-related factors in large truck accidents, accounting for roughly 30% of all truck crashes every year — an estimated 43,000 crashes nationwide in 2025.
In our experience, these crashes are almost always preventable, stemming from maintenance failures, defective parts, and trucking practices that prioritize profits over safety. Having successfully represented thousands of crash victims, our undefeated Texas truck accident lawyers know exactly where to look for the evidence that proves when a brake failure should never have happened. And with Billions won, we have the resources and trial experience to stand up against the largest trucking companies in the world and not just win, but set records.
Read on to learn how semi-truck air brake systems work, why they fail, and how our team can help protect your rights and secure your future after a serious 18-wheeler crash.
How Air Brakes Work on Semi-Trucks
Semi-trucks rely on compressed air to activate their brakes. Air brakes provide a more powerful stopping force and are more reliable for heavy vehicles. The air brake system includes several key components that work together:
- Air compressor: The component pumps air into storage tanks to build up pressure for the braking system
- Air tanks: Store compressed air at high pressure for immediate use when brakes are applied
- Brake chambers: Convert air pressure into a mechanical force that pushes the brake shoes against the drums to create friction
- Slack adjusters: Mechanical levers that transfer force from the brake chamber to the brake camshaft
- Brake drums and shoes: The friction components that actually slow the wheels by pressing against the rotating drums when brakes are applied
When the driver presses the brake pedal, it activates the treadle valve (foot valve). This modulates the flow of compressed air from the storage tanks to the brake chambers. The valve proportionally controls the air pressure based on pedal input, allowing for smooth and controlled braking force.
Types of Air Brake Systems
Two types of air brake systems are used on most commercial trucks, each with distinct characteristics:
- S-cam brakes: The most common type on commercial trucks in the United States. Named for the S-shaped cam that pushes the brake shoes apart. Reliable and cost-effective, but require regular adjustment to maintain proper function and safe operation.
- Disc brakes: Increasingly used on newer trucks and trailers. It uses calipers to squeeze brake pads against a rotor instead of the drums. This setup offers better heat dissipation and more consistent performance. However, disc brakes are more expensive to install and maintain.
Many trucks use auxiliary braking systems on long grades. The engine compression brake (commonly called a ‘jake brake’) harnesses engine compression to slow the vehicle. Some trucks instead use electromagnetic driveline retarders that create resistance in the drivetrain. Both reduce wear on service brakes and prevent brake overheating.
Common Causes of Truck Brake Failures
Many factors could cause brake failures on large trucks. Some of these factors are preventable with the required inspections and maintenance.
Common causes of brake failure include:
- Brake fade: Occurs when brakes overheat, typically on long downhill mountain grades. Heat causes the brake drums to expand away from the shoes, reducing friction and braking power just when it’s needed most.
- Out-of-adjustment brakes: S-cam brakes must be adjusted regularly to maintain proper contact between shoes and drums. Improperly adjusted brakes are one of the leading causes of brake failure in commercial trucks.
- Air system leaks: Leaks in air lines, fittings, valves, or chambers can reduce air pressure below safe operating levels, seriously compromising braking ability.
- Worn brake components: Brake shoes, drums, rotors, and other components wear down over time with use. Worn parts must be replaced before they fail completely.
- Defective components: Manufacturing defects in brake parts can cause premature or unexpected failure, even with proper maintenance and inspection.
Identifying the cause of a truck’s brake failure is essential when filing a truck accident claim. The cause of the brake failure determines who may be liable for economic and non-economic damages.
Federal Brake Regulations for Commercial Trucks
The FMCSA requires commercial truck operators to conduct pre-trip inspections. Pre-trip inspections verify that brakes are functioning properly, air pressure is adequate, and there are no visible defects. Trucking companies must maintain detailed records of all brake inspections, repairs, and adjustments performed on their vehicles.
Violating federal trucking regulations can result in significant fines. The violations could also be used as evidence of negligence in some cases. Trucks with serious brake defects can be placed out of service by roadside inspectors until all repairs are completed.
Who Is Liable When Truck Brakes Fail?
When a truck accident is caused by brake failure, multiple parties may share liability for the resulting injuries and damages:
- The truck driver: May be liable if they failed to conduct proper pre-trip inspections or ignored obvious warning signs of brake problems
- The trucking company: May be liable for failing to maintain the vehicle properly, pressuring drivers to skip inspections, or keeping unsafe trucks on the road
- Maintenance providers: Third-party mechanics or repair shops who performed inadequate repairs or negligent inspections may share liability
- Parts manufacturers: May be strictly liable if defective brake components caused the failure, regardless of maintenance
Prompt investigations and evidence gathering are crucial in a truck accident case. Vital data, information, and evidence could be lost or destroyed.
Injured in a Truck Accident in Houston, TX? Call Our Undefeated Truck Accident Lawyers for a Free Consultation
Truck accident cases involving brake failure in Houston, Texas, require a thorough investigation to preserve evidence. It also requires expert analysis of maintenance records and brake components. At Zehl & Associates, our Houston truck accident lawyers can help you identify all responsible parties and pursue full compensation for your injuries.
Reach out today to schedule a free consultation with a member of our team.
We proudly serve Harris County, Midland County, and throughout the state of Texas. We are located in Houston and Midland and throughout the state of Texas:
Zehl & Associates Injury & Accident Lawyers – Houston
2700 Post Oak Blvd #1000, Houston, TX 77056
(888) 603-3636
Open 24 hours
Zehl & Associates Injury & Accident Lawyers – Midland
306 W Wall St Suite 701, Midland, TX 79701
(432) 220-0000
Open 24 hours