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Variability Analysis of FMVSS-121 Air Brake Systems: 60-mi/hr Service Brake System Performance Data for Truck Tractors
ISSN: 0148-7191, e-ISSN: 2688-3627
Published October 05, 2020 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
In support of the Federal Motor Carrier Safety Administration’s (FMCSA’s) ongoing interest in connected and automated commercial vehicles, this report summarizes analyses conducted to quantify variability in stopping distance tests conducted on commercial truck tractors. The data used were retrieved from tests performed under the controlled conditions specified for FMVSS-121 air brake system compliance testing. The report explores factors affecting the variability of the service brake stopping distance as defined by 49 CFR 571.121, S5.3.1 Stopping Distance—trucks and buses stopping distance. Variables examined in this analysis include brake type, weight, wheelbase, and tractor antilock braking system (ABS). This analysis uses existing test data collected between 2010 and 2019. Several of the examined parameters affected both tractor stopping distance and stopping distance variability. First, the average stopping distance for disc/disc brakes was shorter than either drum/drum or disc/drum brakes, but brake type did not have a statistically significant effect on stopping distance variability. Second, tractors with a gross vehicle weight rating (GVWR) of 45,000-50,000 lb had shorter stopping distances than any other examined weight category. Weight was found to have a significant effect on stopping distance variability; the 50,000-55,000-lb GVWR range had more variability than both the next lower (45,000-50,000 lb) and next higher (55,000-60,000 lb) range.
CitationLascurain, M., Franzese, O., and Siekmann, A., "Variability Analysis of FMVSS-121 Air Brake Systems: 60-mi/hr Service Brake System Performance Data for Truck Tractors," SAE Technical Paper 2020-01-1640, 2020, https://doi.org/10.4271/2020-01-1640.
Data Sets - Support Documents
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- Dunn, A. and Hoover, R. , “Class 8 Truck Tractor Braking Performance Improvement Study, Report 1, Straight Line Stopping Performance on a High Coefficient of Friction Surface,” May 2004.
- 49 CFR § 571.121-Standard No. 121; Air Brake Systems, https://www.govinfo.gov/app/details/CFR-2017-title 49-vol 6/CFR-2017-title 49-vol 6-sec 571-121/summary, Apr. 2020.