1997-12-31

The Effect of the temperature on the emergency braking of road vehicles 973054

It is well known that the temperature and its variation have a great effect on the observed deceleration and on the braking system efficiency. The temperature and its variation between brake disk and pads or braking lining and drums can change significantly the braking factor which in other hand affect the performance of the system in a emergency braking process.
In this work the braking system and the braking dynamics of a standard road vehicle (a bus ) were analytically simulated in a computer programme.
The computer programme can simulate the vehicle in a emergency braking taking in account the temperature variation between braking lining and drums in order to predict the deceleration variation due to the temperature in a standard road test. It is also possible to predict the braking process efficiency for various operational conditions of the vehicle.
The braking forces applied to the vehicle wheels. the vertical forces in the tires, the adherence coefficient between tire and pavement, the slipping sequence of the wheels are also presented in the programme output. All those results were obtained by taking in account the effects of transferring kinetic energy from the vehicle in heat produced by the friction in the braking system.
The results were compared with experimental results from dynamometer tests as well as from road tests carried out by Mercedes-Benz of Brazil. In both cases the comparison between theory and experiments showed good results validating the mathematical simulation. The computer programme can be used by the designer to predict the braking system performance saving time and costs in the development of a new vehicle.

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