Measuring and Analyzing the Pulling Force in Full-Trailer Trucks on Rigid Pavements

Abstract

The pulling force between the tractor and trailer units of four types of 66 full-trailer trucks has been measured using strain gauges for the case of uniform movement of the trucks on rigid pavements. The field study has revealed that the hook connecting the tractor and trailer units of full-trailer trucks has been generally horizontal with an average height of 100 cm above the pavement. A regression analysis has been carried out to correlate the pulling force with the total weight of trailer unit. The analysis has revealed that the strongest correlation is represented by a linear equation having a correlation coefficient of R=0.979. A comparison between the current equations for rolling resistance and the pulling force regression equation has revealed a good agreement, but the rolling resistance equation for trucks moving at very low speed has yielded results significantly higher than the pulling force regression equation. The effect of pulling force on axle load redistribution on a level pavement has been studied too by comparing the static axle loads of 1.2+2.2 full-trailer truck, determined by weighing in a permanent weighing station, with those calculated after consideration of the pulling force for the case of uniform motion. The paper reveals that this effect is insignificant.