The safety of buses in road traffic is very important because of potential hazards of peoples' life and health, damage and loss of freight and high costs of crash effects. The technical state of all vehicles has been examined during required periodical inspections, but in spite of this, the technical conditions of large number of vehicles have been poor. The range of inspections and their frequency have been determined according to the law of each country. The methodology and frequency has been determined in accordance with domestic legislation. The methodology of technical inspections concerns only some important systems of vehicles but not all. For example, anti-lock systems, retarders, adaptive cruise control systems, speed limitation devices etc. have not been examined. The results of examinations of 120 buses and coaches have been presented in this paper. Tests were carried out in scope of securing safety in road traffic. The methodology of compulsory periodical inspections was applied during initial tests. Vehicles were examined on typical control stands and in road tests. A special methodology for road tests for coaches with anti-lock systems was elaborated. Additional checks were carried out in cases when the results of basic tests were unsatisfactory. More than 50 vehicles of the total number of examined buses were faulty.

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The increasing number of road accidents nowadays seems to by a global problem. Apart from the obvious causes of accidents, such as violation of road traffic rules by drivers and pedestrians, the drunk driving, poor quality of road infrastructure, the technical faults of vehicles should also be take into account. Reasons of technical failures can be the failure of parts, components and assemblies caused by aging, poor quality or non-observance of technological norms when they are installed. It is possible to prevent the occurrence of faults by applying warning methods, one of which is obligatory periodic technical inspection. The purpose of this article is to analyze the characteristic features of the systems of technical inspections in automotive transport used in Poland and Russia. It makes it possible to identify common features and distinctive features of systems in both countries.ANALIZA FUNKCJONOWANIA SYSTEMU OKRESOWYCH BADAŃ KONTROLNYCH W TRANSPORCIE SAMOCHODOWYM. DOŚWIADCZENIA POLSKI I ROSJI Streszczenie. Wzrost liczby wypadków drogowym jest obecnie ogólnoświatowym problemem. Razem z głównymi przyczynami wypadków drogowych, tj. naruszanie zasad ruchu drogowego przez kierowców i pieszych, jazdą po spożyciu alkoholu, niedostateczną jakością drogowej infrastruktury technicznej, powinno się także uwzględniać usterki samochodów, jako istotny czynnik pośredni. Przyczynami defektów technicznych samochodów mogą być uszkodzenia części i komponentów spowodowane starzeniem, złą jakością lub nieprzestrzeganiem norm technicznych podczas ich montażu. W celu zapobiegania występowania usterek możliwe jest stosowanie działań zapobiegawczych. Jednym z nich jest okresowe badanie techniczne. Celem niniejszego artykułu jest analiza specyfiki systemów kontroli stanu technicznego samochodów przyjętych w Polsce i Rosji oraz identyfikacja ich cech wspólnych oraz charakterystycznych.

The paper presents the results of investigations concerning the possibilities of application of composite materials in the construction of internal combustion engines. The total mass of the engine can be reduced by allying composite materials, which have a much higher strength than hitherto applied conventional materials. Less thermal expansion allows reducing assembly clearance between the piston and cylinder. The surface topography after the process of machining of composite materials contains hollows, which act as trays for lubricant, wear products and pollution particulates. Therefore, it is possible to reduce friction, fuel consumption, level of exhaust emission and improve the durability of engine. During the investigations, the engine piston made of aluminium matrix composite has been tested. The tests were related to the influence of surface topography of the piston skirt containing Al 2 O 3 particles on the adsorption of lubricating oil, which facilitates lubrication in small displacement test engine. Aluminium matrix composite materials have some disadvantages, too. The most important are higher finishing costs and higher wear of the other sliding element. To reduce the finishing costs of making the suitable surface, special methods for example water jet cutting, have been worked out. To reduce the wear of the other sliding element, reinforcing spherical particles without sharp edges should be applied. Covering the tribological partner-sliding surface with a composite surface layer (e.g. Cr+Al 2 O 3) can result in a relevant reduction of its wear.

Damages of car engine pistons are one of the most expensive failures regarding final consequences and possibilities of engine repair. There have been many research works carried out so far regarding the materials, manufacturing techniques, geometrical shapes and reliability of engine pistons. Notwithstanding all these studies, there is a huge number of piston damage cases. This work is concerned with causes of piston damages and possibilities of early detections. Damaged piston of petrol and diesel engines in passenger and light duty cars have been analyzed. A compendium of case studies of damaged piston causes has been presented. The analysis of different types of damage mechanisms such as thermal and mechanical fatigue, seizure due to insufficient clearances, poor lubrication, overheating and damages due to abnormal combustion have been presented in this work. Faults of electronic control system, engine management malfunction, ignition-timing faults were recognized as the most frequent initial causes of piston damages. Possibilities of early diagnostics of particular causes of damages have been elaborated and presented in the context of total costs of repairs.