Characteristic features of the relation between motor truck mileage and engine cubic capacity

The motor vehicle operation process results in a growth in the vehicle mileage and the rate of this growth is usually characterized by specifying the value of this mileage (in km) calculated per a time unit (month, year, etc.). In this paper, the relation between the specific mileage (km per a time unit) of a motor truck and the engine capacity category has been analysed. Results of calculations based on the observation of the mileage of over 3 600 motor trucks of more than 3 500 kg gross vehicle mass (GVM) have been presented. In the analysis, intervals of equal width were adopted in which the mileage values (in km) were grouped. The percentage of the vehicles whose monthly mileage values belonged to the ith interval was calculated. The resulting set of k discrete values of the percentage of the vehicles with predefined mileage was approximated by a polynomial. The approximation functions are polynomials of the fifth or sixth degree. The curves representing such functions very well describe the distribution of values of the mileage of motor vehicles with engines of over 10000 cm3 capacity. A characteristic feature of the calculated distributions of vehicle mileage values is the fact that the location of the areas of predominating mileage values strongly depend on the engine capacity. The highest values of the monthly mileage of motor trucks with engines of up to 5 000 cm3 capacity do not exceed 9 500 km and increase to 12 500 km for trucks with engines whose capacity exceeds 12 000 cm3. Based on the profiles of the approximation functions, it has been found that the mileage values corresponding to the first mode of these functions decline with increasing engine capacity values. Simultaneously, a decrease can be observed in the percentage of the vehicles with short mileage with a growth in the engine capacity values. Conversely, the motor truck mileage values corresponding to the second mode of the approximation functions markedly increase with growing engine capacity values. An increase can also be seen in the percentage of the trucks with long mileage in the group of vehicles with engines of over 10000 cm3 capacity.