COMMERCIAL VEHICLE FUEL ECONOMY - ARE ADVANCES POSSIBLE?

This article considers various methods of improving the operating economy, in terms of the ton miles per gallon, of a commercial vehicle. It is shown that fuel savings can be obtained by increasing the gross train weight, by governing road speed to match drag and rolling resistance, and by selecting the optimum engine size for the vehicle gross weight. Details are given of the factors affecting the thermal and mechanical efficiency of the diesel engine. The former group include fuel, two stroke versus four stroke , combustion systems, and method of aspiration, whilst the latter group include piston and ring friction, bearing friction, pumping losses, inlet depression and exhaust back pressure, water pump and oil pump power and finally radiator fan power. The author concludes that if all the improvements mentioned in the article could be incorporated into future trucks, improvements in operating economy can be of the order of 10-12 per cent. /TRRL/