Five significantly different passenger car models were studied to determine the degree to which their front/rear brake force distribution and braking efficiency (or ability to utilize roadway friction without wheel lock up) varied. In order to evaluate the variability that manufacturers must contend with when designing braking systems, each of the five vehicle models was evaluated with 10 different sets of new original equipment (OE) proportioning valves and brake linings. Proportioning valves for each test were measured on a laboratory test bench to determine their input-output pressure characteristics prior to installing them on the vehicle. Each of the five vehicles with each set of OE brakes was road-tested with torque transducers at five different vehicle speeds (3, 15, 30, 45 and 60 mph) and with a low-speed (3 mph) European-style roller brake tester. In addition to the torque transducer and roller tester measurements on all of the 10 brake sets, five to eight brake sets for each vehicle were tested on an in-road transducer measurement system (RTP) at 40 mph. In order to determine the degree to which brake balance and braking efficiency vary for vehicles in use, a large sample of vehicles with the same braking systems as the five test vehicles used in the new burnished OE brake set evaluations were rented from consumers and tested on the roller tester and the RTP. Results of this research effort indicate that brake force output varies considerably. For four of the ten brakes evaluated, the variation was more than plus or minus 20% from the mean value. This was primarily due to variability in the performance of the brake linings. In spite of this large variation in brake force output, braking efficiency typically varied about plus or minus 10% from its mean value.

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 62 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00611084
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: VRTC-85-0038, HS-807 681
  • Files: HSL, TRIS, USDOT
  • Created Date: Jul 31 1991 12:00AM