Analysis of the Tractor-Trailer Dynamics During Braking

The tractor-trailer dynamics during braking and the effect of the dynamic distribution of normal vertical reactions between the axles on the brake properties of tractor-trailer is considered. A mathematical model of the process of braking the tractor-trailer (consisting of a wheel tractor and a two-axle trailer), without blocking the wheels was obtained. The conditions for simultaneously bringing to the verge of blocking the wheels of the tractor, trailer and tractor-trailer, as a whole, are determined. Using mathematical modelling methods, method of determine braking conditions of a tractor-trailer without blocking the wheels and the danger of folding is proposed. Obtained analytical expressions, allowing to determine the total normal reactions on the axes of the tractor-trailer and reactions in the connecting hinge of the links between the tractor and the trailer. Also obtained analytical expressions, allowing to determine maximum value of deceleration reached during braking corresponding to the beginning of the early blocking of the wheels of any of the axes of tractor-trailer. Using the obtained mathematical model, the results of the simulation of tractor-trailer dynamics during braking in real time taking into account the directional stability, braking time, braking distance traveled by the tractor-trailer from applying the brakes until it stops and for 5 values of the coefficient of road adhesion - braking applied on all wheels. The most effective distribution of braking forces on each axle of the tractor-trailer, and part of the total braking force attributable to the tractor and the trailer, taking into account the loading of the trailer, empty and full load, are determined. The results can be used in the design, production and operation of wheeled tractor-trailers.