Automotive Brake Failure Causes Severe Accident

Automotive Expert WitnessThis case involves a man who was seriously injured in a traffic accident caused by an alleged fault in the braking system of the plaintiff’s vehicle. At the time of the incident in question, the man was returning to his home after a canoeing trip with his family. Suddenly, the man came upon a truck that was stopped in the middle of the road. When he attempted to apply the brakes, the plaintiff claims that his brakes did not respond, causing him to crash into the back of the truck at high speed. A few days before the accident, the man had taken his vehicle in for a routine inspection, where employees noted a warning light for the car’s anti-lock brakes was illuminated, however, it was unclear if the cause of the warning light was determined and fixed.

Question(s) For Expert Witness

  • 1. What experience do you have specifically with auto brake systems?
  • 2. What could explain a lack of breaking even when the brake cause the brake pedal to go to the floor without engaging the brakes?

Expert Witness Response E-127532

As a Post-doctor I have developed a software suite including the design of brake systems and calculation of how brake system affects the vehicle’s dynamics and performance. I have taught Mechanical Systems Design for 5 semesters, in which the brake system is an independent chapter. I am currently working on a project which involves the modeling of brake systems. Lack of enough friction between the contact surfaces due to wear or failure of the hydraulic fluid system within the caliper and cylinder of a disc brake system may be the reason for the failure here. To determine this with certainty, I would start from some theoretical calculations. Based on the deformed/crashed truck we can estimate its velocity when the collision occurred and based on its braking distance (can be estimated from brake marks), we would be able to estimate the performance of the braking system (assumes that the driver tried to fully stop the truck at that moment). By comparing that performance with the standard braking parameters of that type of truck, we can evaluate if the braking system functions well.

Expert Witness Response E-092158

Most tire shops have company rules and policies in place that, in a nutshell, say their technicians cannot and will not tell the customer any seen issues (up sell findings is what we call it I the industry) nor can they diagnose any issues outside of the scope of oil and lube services and tire replacement and tire repair. I don’t think the shop touched the ABS system. Furthermore, the ABS will not keep the brakes from working properly, the system just keeps the brakes from locking in an emergency stopping situation. He could have locked the brakes up – this would have increased stopping distance greatly. Road conditions are a factor in this case. If he didn’t lock up his tires, and the ABS system was not fixed, the only other possible explanation there is, given the information provided, is there was a leak in the braking system. This leak caused the fluid to run low; possibly causing the ABS light, and eventually leaked all the fluid out. A dry system will not function at all. That may be why the brake pedal went to the floor and the brakes failed to slow the vehicle.


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