TEST BENCH EVALUATION OF HEAVY VEHICLE SUPPLEMENTARY BRAKE SYSTEMS

Abstract

The paper is based on an experimental method regarding the determination of a diesel engine power loss using the motoring method in order to simulate the brake system efficiency. For the heavy duty commercial diesel engine, 1035-L6-DTI, manufactured at Roman Truck Company there were performed specific power loss tests on the engine dynamometric test-bench, changing the braking systems (bleeder engine brake and exhaust brake, individually and combined).As main conclusions of the paper are the following: The introduction of exhaust brake is a very effective braking method as the power loss with closed valve is in average with 97% higher than power loss with open valve in the same condition of normal operation (normal exhaust valve clearances).The introducing of bleeding brake by increasing the normal exhaust valve clearance to a higher, permanent value of aperture increased the power loss with an average of 8% because of increased negative work on the indicated diagram as the system is not isolated and the pressure in combustion chamber is lower.The combination of bleeding brake and exhaust brake is not recommended as power loss decreases in comparison with power loss with exhaust brake. The authors consider that the research work has important tehnical contributions to vehicle safety concerning the efficiency of braking systems applied to engines, bringing experimental results in the literature regarding the study of bleeder and exhaust brake systems.