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Portable Brake Dynamometer

August 9, 2002 the Federal Motor Carrier Safety Administration issued a final rule that allow motor carriers and federal, state and local enforcement officials to use roller brake testers to determine whether a truck or bus complies with brake performance standards in FMCSR 393.  Analysis, Inc., by using this tool, can uncover some of the following problems:

  1. Defective automatic slacks (under & over – adjusted)
  2. Disconnected brakes
  3. Poor low-pressure balance between tractors and trailers (causing excessive wear and premature trailer or tractor wheel lockup)
  4. Very high crack pressures on steering axles (increases jackknife risk)
  5. Reversed bobtail proportioning systems (proportioning when trailer attached)
  6. Broken parking brake springs
  7. Crossed ABS wiring
  8. Pinched or blocked air lines
  9. Sticking or frozen relay valves & quick release valves
  10. Brakes adjusted “backwards” by mechanics
  11. Improperly ground shoes (low brake output)
  12. Leaking wheel seals

The Brake Dynamometer can be used to dynamically test ABS and Automatic Traction Control Systems. By having the wheels rolling and the brakes activating we can:

  1. Check sensor outputs
  2. Verify that sensor wiring is not crossed (left/right)
  3. Fire ABS and ATC solenoids to make sure they are functioning
  4. Verify that solenoid wiring is not crossed left/right and that the hold and dump functions are not reversed.

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