Pneumatic Drum Brake Monitoring System

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There are a huge number of commercial vehicles on the road that still use pneumatic drum brakes. When such vehicles are in use, the brakes must be inspected at a minimum every morning before the first road trip. This is a dangerous process, and in fact may be difficult to perform, due to weather conditions, surface conditions, road clearance or the fitness of the operator.

This is a risky process as the operator must crawl under the vehicle while the brakes are applied and measure the distance that each brake push rod has travelled. Due to the physical design of the air canister, there are limits as to how far out the push rod can go and be within operating limits. If there are push rods extending too far, there is the chance that the brake may not be fully engaged, and the vehicle might be a candidate for Out of Service status. In that case the vehicle cannot be legally operated.

Another area that does not get properly monitored is parking brake failures that can cause a brake to engage while in motion. If that happens in a trailer, the operator may be totally unaware that the vehicle has one wheel locked up. In such a situation, a fire may start because of the heat buildup from friction.

This system is designed to address the two situations; the start of the day brake inspection and notification of issues while operating the vehicle.

Additionally, as the measurements are made electronically, the issue of timing can be measured. With this system, any brake that takes excessive time to engage can be detected. Until now, there has not been a method used to observe trailer brakes do in fact engage before the tractor brakes. This information is not available when measuring by hand with a ruler.

This system can be installed on existing tractors, trailers, single units or buses. Each unit will have a complete system installed with sensors, a control unit and a Bluetooth unit that communicates with the cell phone. The application on the operator’s phone can connect to the vehicle and any trailer(s). Each time the brakes are applied, new measurements are made and sent to the operator.

Functioning brakes are so important that the Commercial Vehicle Safety Alliance (CVSA) conducts a Brake Safety Week where trucks are stopped and inspected specifically for brakes. For example, in 2023 CVSA found brake-system violations amounted to 25.2% of all vehicle out-of-service violations.

With this system in place, the operator can be safe in checking brakes and knowing that any major brake failure would be detected. Every time the brakes are used, they will be measured. Changes can be quickly shared with the operator. The information can easily be shared with weight stations and state patrol inspectors.



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  • Name:
    Robert Dexter
  • Type of entry: