Heavy truck deceleration rates as a function of brake adjustment
About: This article is published in SAE transactions.The article was published on 1991-02-01. It has received 25 citations till now. The article focuses on the topics: Brake.
Citations
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13 Dec 2009
29 Sep 2015
01 Jan 2018
TL;DR: The methods presented allow the forensic engineer to mathematically analyze and determine the effects of brake size, mismatched components, brake adjustment, and system air pressure on the overall braking force and stopping capabilities of air brake equipped commercial vehicles.
Abstract: Braking systems for heavy commercial vehicles differ greatly from the design for light-duty motor vehicles. For example, 49 CFR 571.121 and 49 CFR 393.52 require loaded buses, single unit commercial vehicles, and vehicle-trailer combinations equipped with air brake systems to generate sufficient braking force to meet specific stopping distance, stopping acceleration rate, and brake force-to-weight percentage performance criteria. The combination of unique design, mechanical complexity, and maintenance issues characteristic to air brake systems also pose difficulty in the analysis of air brake system performance. Air brake system performance presents a difficult problem for the forensic engineer with limited familiarity regarding air brake system functions and the elements affecting brake performance. This paper provides insight into the evolution of air brake system standards and the applicable performance criteria for heavy commercial vehicles. The methods presented allow the forensic engineer to mathematically analyze and determine the effects of brake size, mismatched components, brake adjustment, and system air pressure on the overall braking force and stopping capabilities of air brake equipped commercial vehicles.
References
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01 Apr 1985
TL;DR: In this article, the authors provide detailed vehicle information and test data that support the technical report (Volume 1) and a detailed vehicle test data analysis (Appendices A through G).
Abstract: This volume consists of Appendices A through G which provide detailed vehicle information and test data that supports the technical report (Volume 1)
11 citations
01 Apr 1985
TL;DR: In this article, a number of different types of heavy duty air-braked vehicles including buses, trucks, truck tractors and trailers were tested to determine their stopping capability in straight line and turning maneuvers on various types of road surfaces including ice.
Abstract: A number of different types of heavy duty air braked vehicles including buses, trucks, truck tractors and trailers were tested to determine their stopping capability in straight line and turning maneuvers on various types of road surfaces including ice. In addition, the braking force distributions of the vehicles were experimentally determined, several different brake proportioning systems were evaluated and the effect of initial brake temperature on stopping capability was investigated. Results of the testing indicate that stable stopping capability is primarily determined by brake force distribution. If brake force distribution is close to the normal force distribution on the axles of a vehicle, its stopping capability will be optimum; however, if brake force distribution does not match normal force distribution, premature wheel lockup and loss of control will occur before the vehicle is able to achieve full utilization of the friction forces available at the tire/road interface. Brake force distribution on most heavy duty vehicles is fixed at a level that favors the loaded condition and therefore they do not perform as well in the empty condition. In addition, many heavy duty vehicles are "underbraked" on their front steering axles under all operating conditions and would benefit even in the loaded mode if front brake force level was increased. Devices that adjust braking distribution as a vehicle's load changes appear to provide very significant gains in braking performance not only in the straight line stopping situation but also in braking and turning maneuvers.
6 citations