Mobility and Vehicle Mechanics

1-12

Authors: Almir Blažević,Ivan Filipović, Dževad Bibić, Boran Pikula

One of the main reasons of fatigue of the IC engine crankshaft, which inevitably leads to its failure, is the occurrence of high amplitudes of twist angle due to torsional vibrations. Amplitudes of twist angle due to torsional vibrations are particularly pronounced in vibration resonant modes of the crankshaft including crank-gear and other associated elements. An objective way to reduce the torsional vibration amplitudes of twist angle is the application of the torsional vibration dampers (TVD). So far elastic TVD with rubber as elastic element are used for high and medium speed engines for road vehicles. The main reasons are simple construction, reliability and relatively low costs of this type of additional elements. Modern production technologies of crankshaft system elements allow implementation of dynamic TVD with springs for high-speed as well for medium-speed engines for road vehicles (e.g. dual-mass flywheel, a damper in the counterweight etc.).This way, reliability is increased and the costs for TVD are reduced. A method for selecting characteristics of the dynamic TVD with springs built in the counterweight (torsional rigidity, inertia inertial mass), as well as an analysis of its impact on the critical values of the angular amplitudes of twist angle due to torsional vibrations are presented in this paper. The results of analysis are compared with the corresponding angular amplitudes of twist angle of the crankshaft with an elastic TVD element, and the potential of amplitudes of twist angle reduction by selection realistic dynamic characteristics of the dynamic TVD are shown. The complete analysis is carried out for a specific medium speed truck diesel engine

23-34

Authors: Darko Stanojević, Nenad Lužanin, Miloš Vasić,Nada Stanojević, Milun Todorović

Paper presents analysis of implementation development of hybrid buses as well as interpretation of different experiences which users of hybrid vehicles have in their exploitation. Particular accent of interpretation was placed on the reducing of fuel consumption, which also indicates reducing of exhaust emissions gases, which can be achieved with implementation of hybrid buses in city traffic companies. Regarding to problem of autonomy which is still present in complete electric vehicles, it can be said that hybrid drive is more acceptable. This paper is involved in answer to the question: Does implementation of hybrid buses in city traffic companies is justified?

53-63

Authors: Slobodan Mišanović, Slaven Tica, Željko Milković, Pavle Krstić, Branko Milovanović

Providing transport facilities to rural people are very important in order to improve the economic lot of the people. In Mysore and Chamarajanagar Districts, transportation is provided by both KSRTC (Public Organisation) and Private Bus Operators. The objective was to study the rural transportation system of these two districts provided by KSRTC and private bus operators and do a comparative analysis and see which organization provides better transportation in the rural areas and also to give some suggestions to improve it. Data were collected by administering questionnaire to the commuters of both public and private bus service.