The performance and durability of tribological components in roller follower valve train is governed mainly by the roller rotational behaviour. Pure rolling of roller on the camshaft surface is essential to achieve the optimum valve train efficiency. The increase in roller slip can lead to high valve train power loss due to increase in sliding friction and can increase the wear rate of mating surfaces of camshaft and roller. In this research work, a modern gasoline engine having end-pivoted roller finger follower valve train configuration has been instrumented to investigate the effects of Wonder Process Craft surface treatment on roller slip. Comprehensive test programme has been undertaken at transient camshaft speeds by employing the New European Drive Cycle under different oil temperatures and pressures. Remarkable reduction in roller slip was recorded for Wonder Process Craft surface treated roller as compared to the original unmodified roller indicating its strong potential of employment in engine valve train. The test rig, surface treatment of roller, instrumentation, experimentation, results and discussion have been presented in detail in this paper.
Purpose This paper aims to present a technique that has been developed to study the wear in the camshaft and tappet. The engine manufacturers use the most suitable materials, lubrication additives and surface coatings to minimize friction in all the components of the engine. Reduced friction results in less wear of critical engine components. The researchers are constantly trying to find an improved lubrication formula which reduces the wear and friction coefficient at a considerably low price. In this regard, the cam follower interface is of much importance because most of the wear occurs in this interface. Design/methodology/approach The tappets and the cam lobes are analyzed to determine wear. A two-dimensional optical surface profilometer is used to measure the tappet wear, and a high-resolution linear variable differential transformer is used for the measurement of cam lobes. Tests are conducted on Mercedes Benz engine OM 646 under constant camshaft speed, constant inlet lubricant temperature and constant lubricant pressure to study the oil rheology on cam tappet wear. Findings The results show that the wear occurs on the cam tappet interface, which is almost a linear phenomenon, and it increases with use. Originality/value Customized jigs were made to measure wear of camshaft and tappet.
This work is focused on techno-economic performance evaluation of grid connected wind turbines of different power ratings (2 MW and 3 MW) at six coastline areas of Pakistan using RETScreen software. Software imports the weather data of selected locations from its database reported by National Aeronautics and Space Administration. Software outcomes indicate the unadjusted energy production, gross energy production and capacity factor of wind turbines. Comparative study shows that the wind turbine of either rating installed in Jiwani, having capacity factor 33.7% (of 2 MW turbine) and 36.8% (of 3 MW wind turbine) produces ~64% more gross energy than at Karachi and ~4% more than that at Ormara location. Financial viability of wind power project installation is evaluated considering economic determinants and life cycle savings. Technical analysis also reveals the amount of electricity exported to grid. Comparative performance of 3 MW and 2 MW wind turbines is evaluated, and 3 MW wind turbine is found more viable and profitable. Jiwani is found the most favorite location for wind power project installation.
As global demand for oil and gas increases, drilling directional and horizontal wells safely, efficiently and economically requires the best in expertise and technology. The drilling strategy required to reach these targets utilizes one of the several available directional drilling techniques which includes the use of Whipstock, Bent Sub, conventional directional Bottom hole assemblies, Rotary steerable system and positive displacement mud motors. Poor well trajectories become the matter of serious worry in deep and deviated sections of the wells with higher dogleg severity, lower ROP, tolls stucking which causes huge economic loss to the operators. In worst case scenarios the in-adequately drilled directional wells are abandoned. The main objective of this research study will be the intermediate drilling section of the well where the steering of the trajectories like directional drilling trajectories i.e. Slant well, S shaped well and Horizontal wells that will be considered for analysis. This study will analyze the performance of RSS and conventional mud motors, on the basis of rate of Penetration (ROP), drilling depth, and borehole quality.
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