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Performance Based Brake Testing Technology

E-Squared Engineering staff have conducted research and served in an advisory capacity on the Federal Highway Administration Performance Based Brake Testing (PBBT) Technology Working Group.  This effort was established to evaluate the effectiveness of various technologies and develop standards that will help ensure uniform testing procedures.  Brake violations are the number one safety violation on trucks on the road today.  The FHWA, State DOTs, motor carriers, vehicle manufacturers and insurance companies all realize the positive role that PBBTs can play in increasing safety - IF they are used correctly.  At E-Squared Engineering, we have the expertise to help our clients understand PBBT capabilities and limitations - AND we can provide training on how to use them correctly.

Below are some examples/pictures of the Flat Plate Brake Tester and the Roller Dynamometer Brake Tester.

Flat Plate Brake Tester

    

         

The Flat Plate Brake Tester has 4 plates and measures weight, horizontal, and vertical forces.  Roughly speaking, the test is conducted by having the driver roll each axle over a plate at a very slow speed and apply the brakes at full force.  The computer, using both the horizontal and vertical forces measured by the plate sensors, calculates the actual braking force applied at each axle.  This performance based measurement tells the inspection personnel and the driver the actual braking capability for the vehicle AS LOADED.  This is a departure from current testing measures which can only predict braking force at an arbitrary design loading.  Some states are using PBBT devices for screening purposes to identify vehicles with non-functional brakes.

Roller Dynamometer Brake Tester

  

 

The roller dynamometer is another PBBT that measures the braking capability of the vehicle AS LOADED.  This system works a little differently than the flat plate brake tester.  The 'roller dyno' works by connecting pressure lines to the the truck's brake lines (to measure pressure).  The driver then drives each axle on top of the 'roller dyno' and stops.  The rollers on the machine then turn the truck tires (which are in neutral).  The driver is then instructed to slowly apply the truck's brakes while the rollers are spinning the tires.  The 'roller dyno' measures the physical resistance that the truck's brakes are applying to the 'roller dyno'.  At the same time, the pressure in the brake lines are measured by the computer system.  The computer uses the recorded pressure in the brake lines accompanied by the physical resistance that the truck's tires are applying against the 'roller dyno' to calculate the braking force.  This process is repeated for each axle of the truck to determine the AS LOADED braking capability of the vehicle.  Again, this is NOT a predictive test.  It is actually measuring the 'true' braking capability of the vehicle.  In essence, a performance based test.  Two additional important features of this type of machine are that some models are portable (like the one shown), and they can also diagnose anti-lock braking system (ABS) problems and failures.  This latter point is especially important because ABS tests today consist of checking to see if a light comes on (predictive test) rather than an actual test of the ABS brake performance (performance based test).

For more information on PBBTs or how E-Squared Engineering can help you achieve your organizational goals - give us a call or type us a note.  We look forward to the opportunity.  After all, we can't be successful unless we help our clients become successful - first.  (see the home page for contact information)

 

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Last modified: November 23, 2004