RESISTANCE TO VEHICLE MOVEMENT

The basic task of the theory of vehicle motion is to study the effect of forces on the vehicle, ie their causes and consequences. Any vehicle that moves, such as a car, is an object that is exposed to certain resistance forces. The resistance forces acting on a moving vehicle can be divided into internal and external resistance forces. Internal resistance forces mean all forces acting during the transmission of power from the motor to the wheel. Therefore, these forces of resistance are called internal forces. From the point of view of the impact on the vehicle, the forces can be different from each other. In this sense, one should, first of all, distinguish between propulsive forces, which tend to accelerate the vehicle, and resistance forces, which oppose movement, ie which tend to slow it down. Resistance forces when moving the vehicle from a standstill (starting the vehicle from a place) depend on the condition of the road, tires and vehicle weight, and originate from plastic and elastic deformations of the ground, elastic deformations of wheels and inertial forces as resistance forces during acceleration. Motor and trailer vehicles are exposed to various forces during their movement. These forces differ not only in the character and mode of action, but also in the influences they cause on the movement of the vehicle and its performance. The following forces oppose the movement of the vehicle at a steady speed: air resistance forces Rv, rolling resistance forces Rf, ascent resistance forces R and traction resistance forces Rp. However, when moving at a non-stationary speed, the force of inertia Ri joins the above-mentioned forces. The force of rolling resistance of wheels on the road depends primarily on the type of wheel and the type and quality of the road. Air or wind resistances occupy a significant place, so that nowadays special attention is paid to the shape of the vehicle, or rather aerodynamics, as one of the important factors influencing fuel consumption and dynamic behavior of vehicles on the road. Special attention is also paid to the construction of the shape of the side surfaces, since the force of the crosswind does not act in the center of gravity of the surface, but in its metacenter, so that the stability of the vehicle to the crosswind depends on the mutual position of the center of gravity . Climb resistance, as the name suggests, occurs on a climb and together with rolling resistance together form a road resistance. In addition to these resistances, we also have the resistance of the trailer and the resistance of the inertial forces. taking into account all the resistances that oppose the vehicle we can come to the conclusion that they all play a big role in fuel consumption, vehicle speed and stability. Which means that a low coefficient of air resistance increases the maximum speed and at the same time reduces fuel consumption and wind noise. So the reduction of road resistance and all other resistances when moving a vehicle is a constant trend of vehicle manufacturers