Search Results

In heavy duty diesel engines, exhaust gas recirculation is often preferred choice to contain NOx emissions, in this a part of exhaust gas is tapped from exhaust manifold or later and recirculated to air intake pipe before intake manifold. Critical to such engines is the design of air intake pipe and intake manifold combination in view of proper exhaust gas mixing with intake air. The variation in exhaust gas mass fraction at each intake port should be as minimal as possible and this variation must be contained within +/− 10% band to have a minimal cylinder to cylinder variation of pollutants. Exhaust gas homogeneity for various intake configurations was studied using three-dimensional computational fluid dynamics for a 4 cylinder, 3.8 L, Diesel fuelled, common rail, turbocharged and intercooled heavy duty engine. Flow field was studied in the computational domain from the point before exhaust gas mixing till all the four intake ports.

With advancement of technology, better safety and higher vehicle reliability is primary requirement of end customer especially in public transportation. Hence there exist challenges in design and development of steering system for long haulage and tipper application. In the steering system, track rod is used to steer both the front tyre under different operating condition assisted by power steering system. This paper deals with the failures observed on track rod in long haulage and tipper application with loading conditions. Also the methodology adapted to resolve the field failures.

Commercial vehicle industry is presently striving towards development of buses with enhanced passenger safety and comfort. This calls for additional components and aggregates that eventually lead to increase in the overall length and gross vehicle weight (GVW) of the bus for the same passenger capacity. Usually, steering system of longer front overhang (FOH) vehicles have multiple linkages such as bevel box arrangement or intermediate pivot arm arrangement instead of single direct draglink because of packaging and design constraints. In this work, an attempt has been made to design the steering system for one of the longer FOH bus with single direct draglink arrangement. Here, single draglink was packaged and designed with commercially available higher strength tube material. Design optimisation of steering geometry was carried such that the steering performance was atleast on par with existing performance.

The Indian automotive sector is experiencing a major shift, focusing predominantly towards the levels of quality, reliability and comfort delivered to the customer. Since the entry of global players into the market, there is a rising demand for timely product launches with utmost priority to reliability. In any vehicle, engine isolation systems play a critical role in isolating the engine vibrations from the vehicle chassis. This project details on how testing can aid in reducing the launch time as well as estimating the reliability of the component when used in a different application/vehicle. It proposes a methodology to formulate a life model for the engine mount considering various combinations of predictor parameters affecting its performance over its design life. In order to maintain good correlation with the field (which considers the loading pattern and the environmental factors), warranty data was analyzed and the predictors were chosen appropriately.

Commercial vehicles have steering systems with one or more steering links connecting the steering gear box pitman arm and front axle steering arm. In case of twin steer vehicles, intermediate pivot arm is used to transfer the motion proportionately between the two front axles. Intermediate pivot arm is also used in some longer front over-hang vehicles to overcome their packaging constraints and to optimize the mechanical leverage. The pivot shaft is a mechanical part of the intermediate pivot arm assembly upon which pivot arm can swivel in one axis. Steering forces transferred through the drag links generates resultant forces and bending moments on the pivot shaft. In this work, study has been carried out on premature failure of the pivot shaft in city bus application model (Entry + 1 step). Metallurgical analysis of failed part indicated the failure to be due to fatigue. Pivot shaft was tested in rig with similar load conditions in order to replicate the failure.