When reconstructing a highway accident involving a heavy truck, an accurate deceleration rate is often an elusive piece of the puzzle. This paper presents a method for calculating the deceleration rate ofa heavy truck equipped with an air-mechanical brake system. Traditionally a deceleration rate had been more an estimate of the percent of wheel lock-up based on the brake adjustment, and then proportioned to the loading on the axles. Equations for two configurations of brake chamber size and slack adjuster length were written by engineers at the National Highway Traffic Safety Administration's (NHTSA) Vehicle Reserach and Test Center (VRTC) to describe braking torque as it varies with pushrod stroke. These equations were developed by means of a regression analysis, to fit a curve to dynamometer data produced at the VRTC in East Liberty, Ohio. One this braking torque is converted to a barking force, it can be compared to the braking force available at the tire/road interface. This comparison allows the reconstrutionist to evaluate which wheels will lock and to calculate an accurate deceleration rate.


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    Title :

    Heavy truck deceleration rates as a function of brake adjustment


    Additional title:

    Berechnung der Verzögerung schwerer Nutzfahrzeuge als Funktion der Bremseneinstelllung


    Contributors:

    Published in:

    Publication date :

    1991


    Size :

    17 Seiten, 5 Bilder, 9 Tabellen, 7 Quellen



    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




    Heavy Truck Deceleration Rates as a Function of Brake Adjustment

    Heusser, Ronald B. | SAE Technical Papers | 1991


    Heavy truck deceleration rates as a function of brake adjustment

    Heusser,R.B. / National Transportation Safety Board,US | Automotive engineering | 1991



    Calculation of heavy truck deceleration based on air pressure rise-time and brake adjustment

    Bartlett,W.D. / Mechanical Forensics Engng.Services,US | Automotive engineering | 2004