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Fuel consumption has been a core consideration since the beginning of the transportation era. These are reasons related to our environment, and to economics. In the competitive truck industry fuel consumption is an important sales argument, since customers on an average drive their trucks for distances of 150 000 km per year, which means that fuel becomes a large part of the lifetime cost for a vehicle. Existing braking system design in commercial vehicles are basically air assisted, which utilizes the compressed air from reservoir, which is being replenished based on requirement by a positive displacement compressor, generally driven directly by vehicle power pack. In this paper, an effort has been made to partially use the energy stored in the springs (induced due to road undulations) for compressed air generation through a single acting positive displacement pump.

Fuel consumption for heavy trucks depends on many factors like roads, weather, and driver behaviour that are hard for a manufacturer to influence. However, one design possibility is the power-train configuration. In this paper, driveline of a heavy-duty truck is optimised using the six-sigma methodology. The focus of the task is selection of a power train configuration that gives the lowest fuel consumption for each transportation task. To reduce fuel consumption, it is important to choose a powertrain combination (gearbox, rear axle, tire dimension) that allows efficient use of the engine. Such an optimization of powertrain configuration is a complex task, but current simulation techniques provide means to reduce costly testing by replacing it partly with analysis. The DMAIC (Define, Measure, Analyze, Improve & Control) steps are followed to generate alternate solutions of the descriptive problem.

Modern medium duty diesel engines are all developed with engine brake as a standard feature. The main purpose of the engine brake in an automobile is to deliver high vehicle retardation, engine safety and longer foundation brake life. It allows the driver to possess complete control of the vehicle while driving downhill without the need for frequent usage of foundation brakes. This intern prevents the engine revs from exceeding the safe limit thereby protecting the engine. It also help reduce the fuel consumption by avoiding unnecessary braking and thereby necessitating to accelerate again. Typically the braking power in a diesel engine is generated by closing the exhaust system partially or completely. This would increase the back pressure in the exhaust circuit and thereby increase the piston work of the engine. This negative work is used for vehicle braking. This system is called as “Exhaust brake”.