Braking performance of trucks with trailer

Pressure values were measured from suspension?s air bag for three different types of truck-trailer combination to calculate every axles load distribution which were used to calculate optimum braking forces with the given pressure-force formulas by air pad manufacturer. Firstly three-axle tractor-trailer combination, secondly trailer with walking beam suspension and finally two-axle tractor, single-axle semitrailer and double-axle trailer combination were studied. Opposite friction forces were calculated to make optimum braking in 9 different load scenario. Calculated values were shown by graphics in thesis.Some assumptions were admitted such as truck?s and trailer?s weight, location of the center of gravity etc.If we fed the program which was written by EES with updated parameter, we can calculate optimum braking forces in every vehicle combination and every variable road conditions such as wet, dry, curve?etc.