Wyniki wyszukiwania - Biblioteka Nauki

1

Possibilities for increasing maneuvrability of heavy commercial vehicle

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Lozia Z. , Simiński P.

Archives of Transport

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2006

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tom Vol. 18, iss. 3

57-65

EN

The growing density of real estate developments in municipal areas of the European countries has resulted over the past few years in a more intensive traffic of heavy commercial vehicles, travelling through narrow and sinuous streets of the cities. In urban areas with high density of real estate developments, the traffic of commercial vehicles with heavy and medium-sized load capacity very often faces serious difficulties due to the large turning radius of those trucks. Therefore, seeking new solutions through systems that reduce vehicle turning radius makes sense, and in particular those which are used by fire departments, technical services (technical emergency assistance, assembly vehicles, truck-mounted cranes, etc.) and municipal vehicles, as they are often required to operate in hardly accessible urban areas of seriously limited maneuver space. Vehicle maneuverability means an ability to move alongside arcs of small radiuses. The movement usually commences with velocity not exceeding 20 km/h. The use of asymmetric operation of the braking and driving system may be an interesting way to increase vehicle maneuverability. This is an idea that was used in crawlers and wheeled armored vehicles and then transferred into road-wheeled vehicle designs. This proposal does not generate excessive adaptation costs, as it uses executive components of ABS and ASR systems that are nowadays more commonly used in vehicles. The simulation investigation presented in the paper for three-axle vehicles shows that the most effective method is an all wheels steering system that produces a 33.6% reduction of turning radius. The second most effective way is the internal wheels braking (in relation to turning centre) for 6x6 driving configuration. For such a case, a 28.3% reduction of turning radius is possible. For 6x4 driving configuration, a 26.1% reduction of turning radius is possible. Many of the test results, obtained on icy and wet surfaces, yield a higher reduction of turning radius than those performed on a dry one. The achieved results prove a hypothesis about a possibility for increasing maneuverability of three-axle vehicle, which has been initially assumed. The optionally considered application to steer a turn of all wheels (effecting in: 6WS system) is combined with a need to make many expensive modifications in the vehicle design.

PL

Wzrastająca w ostatnich latach gęstość zabudowy obszarów miejskich w Polsce i w innych krajach europejskich powoduje wzmożony ruch pojazdów ciężarowych po wąskich i krętych ulicach miast. Jest on znacznie utrudniony ze względu na duże wartości promieni skrętu tych pojazdów. Jak widać z powyższego, celowe jest poszukiwanie nowych rozwiązań konstrukcyjnych zmniejszających wartość promienia skrętu samochodów, w szczególności tych, które są używane przez straż pożarną, służby techniczne (pogotowie techniczne, samochody montażowe, żurawie samochodowe i inne) oraz pojazdy komunalne. Są one często wykorzystywane do prac w trudno dostępnych obszarach miejskich o znacznie ograniczonej przestrzeni manewrowej. Przez zwrotność pojazdu rozumie się zdolność do ruchu po łukach o małych promieniach. Odbywa się on zazwyczaj z prędkością nie większą niż 20 km/h. Interesującym sposobem zwiększenia zwrotności pojazdu może być wykorzystanie asymetrycznego działania układu napędowego i hamulcowego. Jest to przeniesienie do konstrukcji drogowych pojazdów kołowych pomysłu zrealizowanego w pojazdach gąsienicowych i kołowych transporterach opancerzonych. Propozycja ta nie niesie zbyt dużych kosztów adaptacyjnych, gdyż wykorzystuje elementy wykonawcze układów ABS i ASR, coraz powszechniej stosowane w samochodach ciężarowych. W artykule przedstawiono wyniki badań symulacyjnych oceniających możliwość zmniejszenia minimalnego promienia skrętu trzyosiowego samochodu ciężarowego. Wykorzystano własny model symulacyjny ruchu i dynamiki pojazdu. Został on pomyślnie zweryfikowany eksperymentalnie. Jako sposób zmniejszenia minimalnego promienia skrętu zaproponowano przykładanie momentu hamującego do kół jezdnych strony wewnętrznej oraz stosowanie wszystkich kół kierowanych w układzie 6WS. Badania przeprowadzono dla różnych wariantów: konfiguracji napędu, stanu nawierzchni drogi, prędkości jazdy oraz obciążenia pojazdu.

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Heavy vehicle crashes in Addis Ababa: Relationship between contributing factors and severity of outcomes

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Tulu G. S. , Lisinge R. T. , Wedajo B. T.

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tom Vol. 7, No. 2

25--40

EN

Random parameter logit regression is used to analyze police-reported data on 8,253 heavy vehicle-related crashes in Addis Ababa between July 2014 and June 2017. The analysis shows that fatal crashes are more likely to occur during the day and on weekdays, particularly when the circulation of trucks is high. It also shows the disproportionately high involvement of young drivers in heavy vehicle crashes in the city. However, the likelihood of crashes resulting in fatalities and serious injuries increases slightly compared to those resulting only in property damage as the age of drivers increases. Low levels of drivers' education, the fact that drivers are often not the owners of vehicles, ownership of vehicles by companies and government organizations, and inappropriate road medians' inappropriate design are also significant contributors to fatal crashes. Curbing deaths and injuries from heavy vehicle crashes in Addis Ababa requires strict enforcement of traffic rules and regulations, particularly speed limits; reforms in driver's training and certification; improved safety culture of vehicle owners and design of road infrastructure. Ethiopia's national road safety strategy launched in July 2022 addresses these issues. Hence the government is taking steps in the right direction.

3

A comparison of engine emissions from heavy, medium, and light vehicles for CNG, diesel, and gasoline fuels

67%

Yasar A. , Haider R. , Tabinda A. B. , Kausar F. , Khan M.

Polish Journal of Environmental Studies

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2013

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tom 22

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nr 4

EN

Like other developing countries (Brazil, Argentina, and India) compressed natural gas (CNG) is becoming a popular vehicular fuel in Pakistan. Rapid shifting of diesel and gasoline vehicles to CNG has brought Pakistan the highest number of CNG vehicles in the world. To quantify a possible decrease in vehicular emissions for different types of vehicles, engine and fuel types were monitored for five parameters: SO2, CO, NO, hydrocarbons, and smoke opacity. Emissions from heavy vehicle engines shifting from diesel to CNG showed a decrease in HC (14 times), NO (2.8 times), and smoke opacity (3.2 times), while shifting diesel car engines to CNG resulted in reduced emissions of HC (24.6 times), NO (2.8 times), and smoke opacity (6 times). However, switching of light vehicles such as gasoline car engines to CNG released low emissions of HC (4.6 times), smoke opacity (1.2 times), SO2 (1.2 times), and CO (1.1 times), but an increase in NO (1.2 times) was observed. Similarly, a 4-stroke CNG rickshaw engine increased NO emissions by 1.4 times over a 4-stroke gasoline rickshaw engine.