Intensity of motor trucks operation versus vehicles’ age, in several categories of engine cubic capacity

Changes in the vehicle operation process, which take place with vehicle’s age, have been analysed on the grounds of data collected for over 3 000 motor trucks of more than 3 500 kg gross vehicle mass (GVM), being now in use in Poland. The analysis has covered a 20-year vehicle operation period (referred to as “service life planned”); the distance travelled by a vehicle during this period has been called “target mileage” (expressed in kilometres). As a measure of the intensity of vehicle operation, the “monthly mileage” has been adopted. The monthly mileage values specified in the article strongly depend on the category of engine cubic capacity. Some important characteristics of the mileage growth process, noticed in the recent years along with an intensive development of the road transport, have been presented. The vehicle mileage growth process has been shown for four categories of engine cubic capacity, on the grounds of regression lines based on a polynomial model. The vehicles with engines of more than 10 000 cm3 capacity reach more than 1/3 (i.e. 34.7-36.6%) of their target mileage for the first 60 months of operation, while covering only 2-5.3% of this target mileage during the last two years of their 20-year service life planned. During the first 5 years, the intensity of operation of vehicles belonging to this engine capacity category is four to five times as high as that determined for the last 5 years of the 20-year vehicle operation period under analysis. Calculations carried out have shown that the dataset under analysis includes vehicle categories where 90% of the target mileage is reached as early as after 69-70% of the service life planned. This shows that motor vehicles having been used for a short time predominate in the road transport of goods in Poland and that there is an interrelation between the rates of changes in the vehicle operation intensity and the engine capacity

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

Ocena procesu narastania przebiegu podczas eksploatacji samochodów ciężarowych w kilku kategoriach pojemności silnika

The intensity of use of motor vehicles and the range of the transport jobs performed change during the many-year operation of such vehicles. The changes are introduced in result of ongoing analyses of actual current vehicle operation costs, reliability, and performance characteristics. The changes in the vehicle operation process, taking place with vehicle’s age, were analysed on the grounds of the mileage of over 9 000 motor trucks. The analysis covered a 20-year period of vehicle operation. The analysis results were used to estimate the mathematical models that describe the basic characteristics of the mileage growth process, with changes in these characteristics as observed in the recent years along with an intensive development of the road transport in Poland. Models of vehicle mileage growth have been developed for seven categories of engine cubic capacity. The coefficients of model equations have been given and the accuracy of the mileage values calculated on these grounds has been comprehensively evaluated. The relative measures of the scatter in the mileage values obtained from these models do not exceed 12 % of the average values determined from experimental data. A procedure has been proposed that leads to evaluating the mileage growth process and is based on the experience having already been gained in this field. It has been shown that the mileage growth process is strongly related to the engine cubic capacity. The mileage growth process is an important source of information for the planning of vehicle operation, forecasting of costs, and estimating of exhaust emissions and energy consumption in the whole cycle of operation of motor vehicles by transport companies.W czasie wieloletniej eksploatacji samochodów zmianie ulega intensywność ich użytkowania oraz zakres realizowanych zadań transportowych. Zmiany te są rezultatem analizy kosztów eksploatacji, niezawodności oraz osiąganych parametrów trakcyjnych. Zmiany w procesie eksploatacji, które zachodzą wraz z wiekiem samochodów, analizowano na podstawie przebiegu prawie 9000 samochodów ciężarowych. Analizowany jest dwudziestoletni okres eksploatacji pojazdów. Rezultaty tej analizy wykorzystano podczas estymacji modeli matematycznych, które opisują zasadnicze cechy procesu narastania wartości przebiegu, pojawiające się w ostatnich latach wraz z intensywnym wzrostem transportu drogowego w Polsce. Opracowano modele narastania przebiegu w siedmiu kategoriach pojemności silnika. Podano współczynniki równań tych modeli oraz dokonano wszechstronnej oceny dokładności obliczonych na ich podstawie wartości przebiegu. Obliczone względne miary rozrzutu wartości przebiegu z tych modeli nie przekraczają 12% od wartości średnich, wyznaczonych z danych eksperymentalnych. Zaproponowano procedurę postępowania, która prowadzi do wyznaczenia oceny procesu narastania przebiegu i jest oparta na dotychczasowych doświadczeniach w tym zakresie. Pokazano, że proces narastania przebiegu ma silny związek z pojemnością silnika. Proces narastania przebiegu jest ważnym źródłem informacji podczas planowania eksploatacji pojazdów, prognozowania kosztów, a także oceny emisji spalin i zużycia energii w całym cyklu eksploatacji samochodów w firmach transportowych

Analysis of displacement of a concrete barrier on impact of a vehicle. theoretical model and experimental validation

A vehicle hitting a traffic barrier creates a major threat to traffic safety as a result of displacement of components of the barrier by the forces transferred from the vehicle. We built a theoretical model of the dynamics of such processes and behaviour of concrete barriers set on various types of surfaces. We calculated the displacement as a function of vehicle impact energy and barrier base. We completed analytical approximation for our calculations and we referred the theoretical results to experimental test results. This validated our model of barrier and vehicle movement dynamics as fully qualified for use in the planning of safer barriers and evaluation of barrier effect on traffic. Basing on our calculations, we determined that a second-order polynomial can be used for describing the lateral displacement of a barrier placed on various types of surfaces for a wide range of impact energies (actually, from O to 120 kJ). The courses of the approximating function represent an efficient model for determining the maximum lateral displacement of a concrete barrier on impact of a B or C segment vehicle

Protective function of the road barrier and the car impact energy absorption

W artykule dokonano analizy procesu wypełniania funkcji ochronnej przez bariery w ruchu drogowym, czyli odpowiedniego oddziaływania na pojazd, który uderzył w barierę oraz jednoczesnego pochłaniania energii uderzenia tego samochodu. Rozważano zagadnienie absorbowania (przez barierę) części energii kinetycznej uderzającego samochodu w skojarzeniu z przesunięciem poprzecznym bariery, jako skutkiem uderzenia. Przedstawiono obliczenia energii uderzenia i pracy przesunięcia bariery. Uzyskano liczbowe oszacowanie udziału pracy przesunięcia bariery w ogólnym bilansie energii uderzenia samochodu kategorii M1, z segmentu handlowego B i C, czyli samochodów dominujących w ruchu drogowym. Obliczenia wykonano dla betonowych barier drogowych, ustawianych na różnych podłożach. Wyznaczono analityczne zależności energii rozpraszanej na przesunięcie bariery od kata i energii uderzenia samochodów z segmentów handlowych B i C. Odnoszą się one do różnorodnych podłoży, co umożliwia ich praktyczne wykorzystanie podczas planowania ustawiania barier i analizy zagrożeń bezpieczeństwa ruchu drogowego.The analysis of the protective function of the barrier in the road traffic has been performed. Proper influence on a car hitting the barrier and simultaneous absorption of the impact energy has been analyzed. The issue of absorption (by the barrier) of kinetic energy generated by a hitting car has been considered in relations to the transverse barrier displacement as a result of collision. Calculations of the impact energy and the barrier displacement work have been presented. Numerical estimation of the share of the barrier displacement work in a general impact energy balance for the M1 category cars, commercial segment B and C, i.e., the most common cars in the road traffic, has been obtained. Calculations have been performed for the concrete road barriers placed on different grounds. Analytical dependences of energy dissipated by the barrier displacement on the impact angle and energy of the cars from commercial segments B and C have been determined. They refer to various grounds and allow for practical use when planning barrier arrangement and analyzing road traffic safety issues

The analysis of a car motion path after collision with a concrete barrier

Analizie poddano przebieg toru ruchu samochodu po uderzeniu w betonową barierę drogową. Tor ruchu samochodu w fazie po zderzeniowej jest istotnym wskaźnikiem wypełniania funkcji ochronnej przez barierę. Wykorzystano tu model dynamiki procesu zderzenia i deformacji samochodu uderzającego w barierę oraz ruchu tej bariery. Model przedstawiono w pracy [7]. Przeprowadzono obliczenia, które pokazały wpływ kąta uderzenia i energii uderzenia na tor ruchu samochodu po zakończeniu fazy kontaktu z barierą. Obliczenia wykonano z uwzględnieniem skutków ustawiania barier na różnych podłożach. Rozważono ruch samochodów kategorii M1 (segment handlowy B i C), czyli najczęściej występujących na drogach. Podczas analizy wyników obliczeń brano pod uwagę kąt odejścia toru ruchu samochodu, mierzony bezpośrednio po zakończeniu fazy kontaktu pojazdu z barierą. Oddzielnej ocenie poddano odległość toru ruchu środka masy samochodu od krawędzi bariery w jej położeniu statycznym. Dokonano analitycznej aproksymacji wyników obliczeń i uzyskano zależności wielkości charakteryzujących przebieg toru ruchu samochodu od kąta i energii uderzenia w barierę.A course of a car motion path after collision with a concrete road barrier has been analyzed. A car motion path at the postimpact stage makes a significant index of the protective function fulfilled by a barrier. A model of the impact process dynamics and deformation of a car hitting the barrier as well as the barrier motion have been used in this work. That model is presented in [7]. Calculations have been carried out that indicated the influence of the impact angle and impact energy on the car motion path after completion of the barrier contact stage. Calculations have been carried out considering the effects of placing the barrier on different types of the ground. Motion of the M1 category cars has been considered (commercial segment B and C), that is the most common cars on the roads. During the analysis of computation results, the car path deflection angle, measured just after the end of the car and barrier contact stage, has been considered. A separate evaluation of the distance between the motion path of the centre of the car mass and the edge of the barrier in its static position, has been performed. Analytical approximation of results has been performed and dependences of values characterizing the course of the car motion path on the impact angle and the impact energy have been obtained

Analysis of the impact of road category and day of the week on accident hazard in the road transport of goods in Poland

The current accident hazard caused by road transport of goods has been analysed, with the location (road categories) and time circumstances (specific days of the week) having been additionally taken into account. Calculations were done that made it possible to quantify this hazard, which is chiefly caused by the traffic of goods vehicles. The importance of this problem is increasing in the situation of persisting strong and steady upward trend in the traffic of goods vehicles. In a recent period of 10 years, the rate of growth of the traffic of goods vehicles was almost twice as high as that of the traffic of passenger cars. The hazard and fatality risk indicator values were estimated by analysing an isolated set of accident data. The period covered by the analysis of the events that occurred in the road transport of goods extended for the years from 2002 to 2011 and the numerical values have been specified in relation to repeatable week-long periods and to four road categories. The calculated hazard indicator values have been compared with the share of goods vehicles in the whole motor vehicle market, road traffic, and goods transport

Characteristic features of the process of growth in the mileage of hybrid vehicles

For a few years, the sales of motor vehicles with hybrid drive systems (referred to as “hybrid vehicles” or “HVs”) have been rapidly growing. However, there is a lack of information about the intensity of operation of vehicles classified in this category, which is completely new. A calculation procedure has been presented that enabled evaluation of the HV mileage growth rate. An analysis of this rate provides grounds for forecasting the changes that are likely to take place in the fleet of motor vehicles, such as the progress in the process of replacement of conventional vehicles with vehicles with alternative drive systems, and this may be a basis for predicting the reduction in fuel consumption and exhaust emissions. Models of the HV mileage growth process have been defined for three different countries. They indicate high mileage growth rates in the initial period of vehicle operation, e.g. until the fourth year of operation of the Auris H cars. The highest mileage growth rates in this period were observed in the Netherlands and Poland. In Germany, this rate was lower by 41%. Significant differences in the intensity of vehicle operation have been observed between the behaviour of HV owners in the countries under analysis. A considerable drop in the annual HV mileage as early as in the fifth and sixth year of vehicle operation is an alarming signal

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

Disk and drum brakes, properties confrontation at present stage of automobile engineering development

Konstruktorzy, dążąc do zwiększenia efektywności środków transportu, proponują m.in. nowe rozwiązania układów hamulcowych. Wprowadza się wysokowydajne systemy sterowania i wspomagania kierowcy w czasie hamowania. Trwają prace nad elektrycznymi układami hamulcowymi. Te zmiany w układach sterowania hamulcami mają istotny wpływ na konstrukcję i funkcjonowanie mechanizmów hamulcowych, tj. tych zespołów, które są bezpośrednio związane z kołami jezdnymi. W pracy opisano właściwości tarczowych i bębnowych mechanizmów hamulcowych, a przede wszystkim zwróconouwagę na możliwości skrócenia długości drogi hamowania i zwiększenia momentu tarcia w hamulcach poprzez wprowadzenie zmian konstrukcyjnych i nowych materiałów. W dalszym ciągu poważnym problemem pozostaje nagrzewanie się hamulców i spadek efektywności ich działania w wysokiej temperaturze. W końcowej części pracy zestawiono w sposób porównawczy charakterystyczne właściwości nowych rozwiązań tarczowych i bębnowych mechanizmów hamulcowych.Constructors, endeavour after increasing means of transportation effectiveness,propose among other things innovations in braking systems. High-efficiency driver's control and aiding systems while braking are brought into practice. Works go on with electric braking systems. That modifications in brakes control systems have essential influence over braking mechanisms construction and work such as systems that are directly connected with wheels. In the work properties of disk drum braking mechanisms were described, first of all attention was paid to possibilities of shorten braking distance and increase brake's moment of friction through bringing innovations as well as new materials into practice. All the time important problem is neating of brakes and decrease of their efficiency in high temperature. In final part of the work distinctive properties of new disk and drum brake's mechanisms were compare