Fundamentals of Vehicle Propulsion and Braking

Vehicle operation fundamentals mathematically describe vehicle behavior based on the general principles of mechanics. A vehicle, consisting of thousands of components, is a complex system. Since this book proposes to discuss electric, hybrid electric, and fuel cell power trains, the discussion of vehicle fundamentals will be restricted to one-dimensional movement. This chapter will, therefore, focus on vehicle performance, such as speed, gradeability, acceleration, fuel consumption, and braking performance. Vehicle operation fundamentals mathematically describe vehicle behavior based on the general principles of mechanics. This chapter focuses on vehicle performance, such as speed, gradeability, acceleration, fuel consumption, and braking performance. The operating fuel economy of a vehicle depends on several factors, including fuel consumption characteristics of the engine, gear number and ratios, vehicle resistance, vehicle speed, and traffic conditions. The resistance usually includes tire rolling resistance, aerodynamic drag, and uphill resistance. The rolling resistance of tires on hard surfaces is primarily caused by hysteresis in the tire materials. When the tractive effort of a vehicle exceeds the limitation of the maximum tractive effort due to the adhesive capability between the tire and the ground, the drive wheels will spin on the ground. It should be noted that for some vehicles no intersection exists between the tractive effort curve and the resistance curve because of a large power plant or a large gear ratio.