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18-wheeler & semi-truck braking accidents

Semi-truck/18-wheeler braking lawyers - law firm - attorneys

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Our law firm's heavy vehicle lawyers understand the unique nature of the braking systems used on 18-wheelers, tractor-trailers, semi-trucks (including doubles and triples), and other commerical vehicles such as buses.  Heavy commercial vehicle braking systems are very different from the hydralic braking systems used in passenger cars, pickup trucks, and SUVs.  Large trucks, such as 18-wheelers or tractor-trailers, utilize an "air brake" system which requires proper maintenance, design, and inspection to work properly. 

If a truck's brakes are defective, the result is often catastrophic serious injuries (including paralyzations, permanent disabilities, scarring, hospitalization, etc) or deaths resulting from 18-wheeler/heavy truck collisions with passenger cars, pickups, or SUVs on Missouri and Kansas highways and roads.  A loaded semi-truck traveling in Kansas City or Johnson County can weigh 80,000 pounds, while a typical passenger car only weighs 4000 pounds.  Physics tells us that the vast difference in the mass between the two vehicles will overcome the safety features (such as crumple zones, door beams, airbags, etc) of cars, pickups, and SUVs, leading to serious injuries and deaths for those in the passenger car.

Our Kansas City area law firm has successfully recovered milions of dollars in personal injury and wrongful death lawsuits involving heavy trucks and passenger cars.  We have filed and prosecuted dozens of lawsuits in Kansas and Missouri State Courts, as well as in Federal Court.  Call us at 913-764-5010 today to speak to a heavy truck (18-wheeler/tractor-trailer) attorney about your personal injury or wrongful death case in Missouri, Kansas, or elsewhere.

Learn more about the braking systems used on 18-wheelers & semi-trucks traveling on Kansas & Missouri roads & highways:

Semi trucks use air pressure, rather than hydraulic fluid, to actuate the brakes mainly due to the much larger braking forces required. This also allows for ease of coupling and uncoupling of trailers from the tractor unit, as well as reducing the potential for problems common to hydraulic systems, such as leakage or brake failure caused when overheated brake fluid vaporizes in the hydraulic lines. The most common failure is "brake fade" usually caused when the "drums" or "discs" and the "linings" of the brakes overheat from excessive use.

The "parking brake" of the tractor unit and the "emergency brakes" of the trailer are spring brakes that require air pressure in order to be released. They are applied when air pressure is released from the system, and disengaged when air pressure is supplied. This is an emergency feature which ensures that if air pressure to either unit is lost, that unit will not lose all braking capacity and become uncontrollable.

A view of semi-trailer brake connections.  The "red" line is emergency/supply and the "blue" is control line.

The trailer controls are coupled to the tractor through two "glad-hand" connectors, which provide air pressure, and an electrical cable, which provides power to the lights and any specialized features of the trailer.

"Glad-hand" connectors (also known as "palm couplings,") are air hose connectors, each of which has a flat engaging face and retaining tabs. The faces are placed together, and the units are rotated so that the tabs engage each other to hold the connectors together. This arrangement provides a secure connection, but allows the couplers to break away without damaging the equipment if they are pulled, as may happen when the tractor and trailer are separated without first uncoupling the air lines. These connectors are similar in design to the ones used for a similar purpose between railroad cars. Two air lines control the trailer unit. An "emergency" or main air supply line pressurizes the trailer's air tank and disengages the emergency brake, and a second "service" line controls the brake application.

Another braking feature of semi-trucks is the engine braking, which could be either compression brake (usually shortened to "Jake brake") or exhaust brake or combination of both. The use of compression brake alone however produces a loud and distinctive noise, and owing to noise pollution, some local municipalities have prohibited or restricted the use of engine brake systems inside their jurisdictions, particularly in residential areas. The advantage to using this instead of conventional brakes is that a truck can travel down a long grade without overheating its wheel brakes. Some vehicles can also be equipped with hydraulic or electric retarders which have an advantage of near silent operation.

ederal Motor Vehicle Safety Standards (FMVSS) 105 and 121 currently require medium and heavy duty vehicles (vehicles with a Gross Vehicle Weight Rating (GVWR) of 10,001 pounds to 26,000 pounds are medium vehicles, vehicless with a GVWR of more than 26,000 pounds are heavy vehicles) to stop, on a high coefficient of friction pavement and with properly working brakes, in the distances shown in Table 1. In comparison, FMVSS 135 basically requires light vehicles (vehicles with a GVWR of 10,000 pounds or less except for motorcycles) to stop, also on a high coefficient of friction pavement and with properly working brakes, in 215 feet (the actual requirement is 230 feet from 62 mph (100 kph)). These standards also set required failed system/emergency brake stopping distances (not shown in this document). Again, the required failed system/emergency brake stopping distances are substantially longer for medium and heavy duty vehicles than for light vehicles.

Heavy truck accident illustration injury death lawyers Kansas City Missouri

Current Stopping Distance Requirements for Medium and Heavy Duty Vehicles such as semi-trucks and 18-wheelers

The semi-truck injury accident lawyers in our law office know that when heavy truck accidents occur on Kansas and Missouri highways/roads, the occupants of cars are most likely suffer severe injuries and often result in fatalities due to the sheer size and weight of these trucks.

That is precisely the reason the Federal Government is proposing new 18-wheeler & semi-truck braking standards.  According to the National Highway Traffic Safety Administration (NHTSA), these new rules could save an estimated 227 lives a year, prevent 300 serious personal injuries and reduce property damage claims by up to $169 million.

New rules on semi-truck brakes are intened to limit semi-truck accidents, the resulting serious injuries, and fatalities on highways including those in Kansas and Missouri

The new federal braking standards state that stopping distances for heavy commercial trucks must improve by at least 30 percent, so that trucks will stop in a shorter distance.  For example, a semi truck traveling at 60 miles an hour will be required to come to a complete stop in 250 feet.  The old standard required 355 feet.

By 2011, 85 percent of all semi trucks will operate by this standard.  Still, the report does not say what braking technologies will be used to limit speeding and decrease stopping distances.

Statistics show that large commercial vehicles are involved in fewer fatal crashes than in the past.  In 2008, there were 4,229 wrongful deaths in crashes involving large trucks, down 12 percent from the 4,822 wrongful deaths recorded in 2007.  We are improving, but until that number is zero, we should continue to look for ways to save lives.Hopefully, this new braking standards for semi-trucks will further limit the staggering car accident statistics plaguing America’s roadways.


Vehicle Type Stopping Distance from 60 mph, Empty Stopping Distance from 60 mph, Loaded
Buses (including School Buses) 280 ft 280 ft
Single Unit Trucks (except Buses)
  • Weight > 10,000 lbs
  • 8,000 - 9,999 lbs
  • 7716 lbs - 7,999 lbs
335 ft
242 ft
216 ft
310 ft
216 ft
216 ft
Truck-Tractors 335 ft n/a
Truck-Tractors with Unbraked Control Trailer n/a 355 ft
Semi-Trailers, Trailers, and Converter Dollies Dynamometer Requirement Dynamometer Requirement

The original, 1970, proposal for FMVSS 121 would have required Buses, Single Unit Trucks, and empty Truck-Tractors to meet a 60 mph stopping distance requirement of 216 feet. (This is identical to the FMVSS 135 light vehicle requirement except for metric system round-off, i.e., the Europeans wanted to have a required stopping distance from 100 kph of 70 meters, not 70.4 meters.) Due to comments and objections from the trucking industry as to their inability, at that time, to meet the 216 feet requirement for all types of medium and heavy duty vehicles, the stopping distance requirements were relaxed to those in force today. However, we believe that due to recent technological advances in medium and heavy duty vehicle brakes, specifically in the area of disk brakes and electronic brake systems (EBS), required stopping distances for these vehicles can be made substantially shorter.



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