# 18-Wheeler Brakes: A Look at Semi-Truck Brake Systems | Attorney Brian White **Table of Contents***[*Expand*]* 1. How Tractor-Trailer Brakes Work 2. Understanding the Braking System 3. How Semi-Truck Brakes Fail 4. Contact the Houston Truck Accident Attorneys at Attorney Brian White Personal Injury Lawyers for Help Today ![Truck accident](https://attorneybrianwhite.com/wp-content/uploads/2025/11/18-Wheeler-Brakes-A-Look-at-Semi-Truck-Brake-Systems-300x200.jpg) An 18-wheeler is much more prone to equipment failures than passenger vehicles. A truck could travel hundreds of thousands of miles each year, leading to much more wear than the average car will experience. Moreover, semi-truck or lorry brakes must work harder than a smaller vehicle’s brakes since they can weigh up to 80,000 pounds with a fully loaded trailer. The consequences can be catastrophic when semi brakes fail. A [truck accident](https://attorneybrianwhite.com/houston-tx/truck-accident-lawyer/), particularly one at high speeds, has the power to crush vehicles and their occupants. Victims will often experience severe or even fatal injuries in collisions with runaway trucks. ## How Tractor-Trailer Brakes Work An 18-wheeler uses air brakes to stop. These differ from the hydraulic brakes on your car because air brakes use air while hydraulic brakes rely on brake fluid to do the work. However, the air brakes on a truck and trailer work in the opposite way from your car’s hydraulic brakes. When you press on the brake pedal in your car, you compress a piston inside a master cylinder containing brake fluid. The fluid escapes from the master cylinder to a slave cylinder. Once there, the fluid forces a piston inside the slave cylinder to actuate the brakes and slow the car. One way to visualize this system is to think of two balloons connected to each other’s openings. When you squeeze the air out of one balloon, the other balloon inflates, and vice versa. As the brake pedal squeezes hydraulic fluid out of the master cylinder, the piston inside the slave cylinder moves the braking mechanism to contact the wheels and slow the vehicle. For a legal consultation call [(713) 500-5000](tel:+17135005000) ## Understanding the Braking System A truck has two braking systems that operate using air rather than fluid. The truck’s service brakes work like your vehicle’s brakes, but they use compressed air rather than hydraulic fluid to transmit force from the pedal to the braking mechanism. However, the truck’s parking brake is activated when there is no pressure. In other words, a truck’s parking brake system is actuated when the “balloon” is deflated, exactly the opposite of a car’s braking system. When the engine is running, it operates a compressor. This compressor pressurizes the braking system, [releasing the parking brake](https://auto.howstuffworks.com/auto-parts/brakes/brake-types/air-brake.htm). This system has two benefits. First, air is everywhere, while hydraulic fluid is not. If a truck’s air brake system loses pressure, the compressor can take ambient air and compress it to actuate the brakes. Second, since the parking brake is actuated when decompressed and released when compressed, it is designed to stop the truck when the compressor fails. Thus, an [equipment failure](https://attorneybrianwhite.com/houston-tx/truck-accident-lawyer/equipment-failure/) in the compressor triggers the brakes, while an equipment failure in your car’s braking system leaves you with no brakes. ## How Semi-Truck Brakes Fail Semi-truck brakes are complex systems that can fail for many reasons. However, two leading causes of brake failure are wear and overheating. Wear happens naturally. Brake pads are designed to wear as they slow the wheels. By wearing, they dissipate heat and prevent the brakes from seizing. However, [trucking companies](https://attorneybrianwhite.com/blog/10-largest-trucking-companies-in-the-us/) and drivers have a legal duty to inspect and maintain their vehicles. If they do not replace worn parts, they may be liable for any resulting crash due to their [poor maintenance](https://attorneybrianwhite.com/houston-tx/truck-accident-lawyer/poor-maintenance-truck/). Overheating results from brake misuse. Specifically, drivers understand how to reduce the risk of overheating by using [engine brakes](https://www.cummins.com/components/engine-braking-valvetrain/support/how-an-engine-brake-works). By downshifting, the back pressure in the engine slows the engine speed, which, in turn, slows the truck’s wheels. As a result, the truck slows without using its service brakes. A careless or poorly trained driver might fail to use their engine brakes, leading to overheating and brake failure. [Click to contact](/contact-us/) us today ## Contact the Houston Truck Accident Attorneys at Attorney Brian White Personal Injury Lawyers for Help Today Semi-trucks have braking systems designed for safety. However, no system is perfect, and brake failure happens. In many cases, brake system failure is a result of poor maintenance or driver errors. Our offices Houston — Greenway/Upper Kirby 3120 Southwest Freeway, Suite 350 Houston, TX 77098 Open 24 hours daily Call [(713) 364-1466](tel:+17133641466) [Directions](https://www.google.com/maps/dir/?api=1&destination=Attorney%20Brian%20White%20Personal%20Injury%20Lawyers%2C%203120%20Southwest%20Freeway%2C%20Suite%20350%2C%20Houston%2C%20TX%2077098) Houston — East Freeway 11811 East Freeway, Suite 630-06 Houston, TX 77029 Open 24 hours daily Call [(713) 609-1893](tel:+17136091893) [Directions](https://www.google.com/maps/dir/?api=1&destination=Attorney%20Brian%20White%20Personal%20Injury%20Lawyers%2C%2011811%20East%20Freeway%2C%20Suite%20630-06%2C%20Houston%2C%20TX%2077029) Houston — South Loop 2600 South Loop West, Suite 293 Houston, TX 77054 Open 24 hours daily Call [(713) 281-4904](tel:+17132814904) [Directions](https://www.google.com/maps/dir/?api=1&destination=Attorney%20Brian%20White%20Personal%20Injury%20Lawyers%2C%202600%20South%20Loop%20West%2C%20Suite%20293%2C%20Houston%2C%20TX%2077054) Houston — Katy Freeway 11511 Katy Fwy, Suite 515 Houston, TX 77079 Open 24 hours daily Call [(713) 909-7537](tel:+17139097537) [Directions](https://www.google.com/maps/dir/?api=1&destination=Attorney%20Brian%20White%20Personal%20Injury%20Lawyers%2C%2011511%20Katy%20Fwy%2C%20Suite%20515%2C%20Houston%2C%20TX%2077079) Houston — Clear Lake 1300 Bay Area Blvd, Suite B268 Houston, TX 77058 By appointment only Call [(936) 508-2854](tel:+19365082854) [Directions](https://www.google.com/maps/dir/?api=1&destination=Attorney%20Brian%20White%20Personal%20Injury%20Lawyers%2C%201300%20Bay%20Area%20Blvd%2C%20Suite%20B268%2C%20Houston%2C%20TX%2077058) The Woodlands 1776 Woodstead Ct, Ste. 203 The Woodlands, TX 77380 By appointment only Call [(281) 843-9777](tel:+12818439777) [Directions](https://www.google.com/maps/dir/?api=1&destination=Attorney%20Brian%20White%20Personal%20Injury%20Lawyers%2C%201776%20Woodstead%20Ct%2C%20Ste.%20203%2C%20The%20Woodlands%2C%20TX%2077380) Champion Forest (Cypress) 4606 FM 1960 Rd W, Ste. 444 Houston, TX 77069 By appointment only Call [(281) 843-9777](tel:+12818439777) [Directions](https://www.google.com/maps/dir/?api=1&destination=Attorney%20Brian%20White%20Personal%20Injury%20Lawyers%2C%204606%20FM%201960%20Rd%20W%2C%20Ste.%20444%2C%20Houston%2C%20TX%2077069) --- ### About the Author Brian White ![About the Author Brian White](https://attorneybrianwhite.com/wp-content/uploads/2024/12/brian-white-houston-personal-injury-lawyer-300x300.jpg) [Brian White](https://attorneybrianwhite.com/about/our-attorneys/brian-white/) earned his J.D. from South Texas College of Law in Houston and is licensed to practice in Texas. As a [Board-Certified](https://attorneybrianwhite.com/resources/brian-white-is-board-certified-in-personal-injury-trial-law/) Personal Injury Trial Lawyer, Brian represents clients throughout Houston in cases involving [car accidents](https://attorneybrianwhite.com/houston-tx/car-accident-lawyer/), truck accidents, [motorcycle accidents](https://attorneybrianwhite.com/houston-tx/motorcycle-accident-lawyer/), [brain injuries](https://attorneybrianwhite.com/houston-tx/brain-injury-lawyer/), [wrongful death](https://attorneybrianwhite.com/houston-tx/wrongful-death-lawyer/), and more. Dedicated to giving back, he actively supports local charities and [community initiatives across Houston](https://attorneybrianwhite.com/about/community-involvement/). [Client testimonials](https://attorneybrianwhite.com/about/testimonials/) highlight Brian’s compassion, open communication, and dedication to achieving the best outcomes for those he represents. [Avvo](https://www.avvo.com/attorneys/77098-tx-brian-white-74113.html) / [Justia](https://lawyers.justia.com/lawyer/brian-elliott-white-201630) / [Linkedin](https://www.linkedin.com/in/attorney-brian-white-378410166) / [Facebook](https://www.facebook.com/login/?next=https%3A%2F%2Fwww.facebook.com%2FBrianWhiteLawFirm%2F/) / [Youtube](https://www.youtube.com/channel/UCDdkDcGkbY2GFTzpeTWypFQ) / [Instagram](https://www.instagram.com/attorneybrianwhite/?hl=en) / [Yelp](https://www.yelp.com/biz/brian-white-and-associates-houston) / Call or Text [(713) 500-5000](tel:+17135005000) or Complete a [Case Evaluation Form](/contact-us/) Truck Accidents Blog Posts: [![Interstate vs. Intrastate Trucking](https://attorneybrianwhite.com/wp-content/uploads/2025/04/Interstate-vs-Intrastate-Trucking-300x179.jpg)](https://attorneybrianwhite.com/blog/interstate-vs-intrastate-trucking/) [Interstate vs. Intrastate Trucking](https://attorneybrianwhite.com/blog/interstate-vs-intrastate-trucking/) Many people may not put much thought into interstate vs. intrastate trucking. However, the differences expand beyond [![Electric Semi-Trucks: Good, Bad, or Both?](https://attorneybrianwhite.com/wp-content/uploads/2025/10/Electric-Semi-Trucks-Good-Bad-or-Both-1-300x195.jpg)](https://attorneybrianwhite.com/blog/electric-semi-trucks-good-bad-or-both/) [Electric Semi-Trucks: Good, Bad, or Both?](https://attorneybrianwhite.com/blog/electric-semi-trucks-good-bad-or-both/) The hype around electric semi-trucks is gaining steam. Uber Freight and Tesla recently teamed up to create an EV Fleet [![Insurance Requirements for Interstate Motor Carriers and the MCS-90 Endorsement](https://attorneybrianwhite.com/wp-content/uploads/2025/10/insurance-requirements-for-interstate-motor-carriers-and-the-mcs-90-endorsement-300x200.jpg)](https://attorneybrianwhite.com/blog/insurance-requirements-for-interstate-motor-carriers-and-the-mcs-90-endorsement/) [Insurance Requirements for Interstate Motor Carriers and the MCS-90 Endorsement](https://attorneybrianwhite.com/blog/insurance-requirements-for-interstate-motor-carriers-and-the-mcs-90-endorsement/) Texas is home to some of the busiest highways in the United States, with thousands of commercial trucks transporting [![A truck driver driving within hours-of-service rules.](https://attorneybrianwhite.com/wp-content/uploads/2026/09/A-truck-driver-driving-within-hours-of-service-rules-300x200.png)](https://attorneybrianwhite.com/blog/what-are-truck-driver-hours-of-service-rules/) [How Do Truck Driver Hours-of-Service Rules Affect Accident Cases?](https://attorneybrianwhite.com/blog/what-are-truck-driver-hours-of-service-rules/) Every year, fatigued truck drivers cause thousands of serious crashes on American highways. Many of these accidents --- Source: https://attorneybrianwhite.com/blog/18-wheeler-brakes-a-look-at-semi-truck-brake-systems/