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This paper presents equations for determining the convective heat transfer coefficients of solid and ventilated disc brakes. Analysis of data indicates that the cooling capacity of a ventilated rotor is sharply reduced at lower speeds, and most cooling is provided by the increased surface area. A general relationship derived from road test data is presented that yields the heat transfer coefficient for both disc and drum brakes of commercial vehicles.

This paper reports the results of a study which had as its aim the determination of braking performance currently achievable by buses, trucks, and tractor-trailers, and the improvement of this performance by use of advanced braking systems. Both vehicle testing and analytical techniques, including dynamic modeling and simulation, were used in the program. Performance qualities essential to braking systems are enumerated, which, when given quantitative definition in the light of performance achievable, can form the basis of rational performance requirements for commercial vehicles.

The Findings presented in this paper are based upon the investigation and reconstruction of more than 250 commercial vehicle accidents. Practical methods yielding acceptable results in terms of speed determination and fade and temperature prediction in truck run-away accidents are presented. The importance of accurate and complete data collection with respect to accident scene, mechanical condition of the vehicle, and driver human factors are discussed. The effects of complete, partial and no-wheel lockup on accident reconstruction are discussed for straight and out-of-control motion of the vehicle, including Jack-knifing. The importance of front wheel brakes is considered. The engineering concepts used in the analysis of accidents involving brake fade are presented including factors such as Jake brake, brake adjustment, and heat checking of drums. Driver factors are also considered. Truck rollover mechanics as it applies to braking accidents is reviewed.

The objectives of this third edition of an SAE classic title are to provide readers with the basic theoretical fundamentals and analytical tools necessary to design braking systems for passenger vehicles and trucks that comply with safety standards, minimize consumer complaints, and perform safely and efficiently before and while electronic brake controls become active. This book, written for students, engineers, forensic experts, and brake technicians, provides readers with theoretical knowledge of braking physics, and offers numerous illustrations and equations that make the information easy to understand and apply. New to this edition are expanded chapters on: • Thermal analysis of automotive brakes • Analysis of hydraulic brake systems • Single vehicle braking dynamics