Automobiles have revolutionized the lives of millions of people, changing the way cities are designed and enabling the efficient distribution of goods. Automobiles also play a critical role in the economy by allowing workers to commute long distances and consumers to buy and sell products quickly and easily. Automobiles are used for a wide variety of purposes, from hauling freight to driving passengers around town and beyond. Most automobiles are powered by engines that burn gasoline, which releases carbon dioxide and other greenhouse gases into the air. Because the engine is used for so much of the vehicle’s operation, fuel-efficient design has become a major focus for automotive manufacturers.
The earliest automobiles were horse-drawn carriages with internal combustion engines installed. Developed in the late nineteenth century, these first cars were able to travel long distances more quickly than their predecessors and provided an alternative means of transportation that was faster and cheaper than train or ship travel. Today, there are more than 1.4 billion passenger cars in use worldwide. Despite their widespread use, these vehicles are not without flaws. They can be dangerous when driven poorly by human beings, and their high speed and erratic handling can result in serious accidents. The large number of automobiles has led to traffic congestion in many urban areas, and their combined pollution contributes to global climate change.
Automobiles are complex systems, and the arrangement, choice and type of their components depend on the intended use of the vehicle. For example, a car built for highway speeds requires more powerful engines and higher-capacity transmissions than a model designed to be driven on short trips at low speeds. Similarly, the suspension system of an automobile must be flexible enough to respond to both the road’s surface conditions and the forces exerted on the vehicle by its occupants and cargo.
Most automobiles have from four to eight cylinders. During the compression stroke, each cylinder fires its piston into the cylinder head, which transfers energy to the crankshaft, turning it. The crankshaft then transfers the power to the wheels by turning them. The more cylinders an automobile has, the more powerful its engine is likely to be.
The chassis is the framework to which all other parts of an automobile are attached. It must be strong enough to support the weight of the automobile and sufficiently flexible to withstand the shocks and tension caused by turns, acceleration, and braking. It must also be able to transfer the engine’s power to the tires, which are the only part of the automobile in contact with the road.
A car’s drivetrain includes the engine, transmission, and rear axle. The engine must be powerful enough to propel the automobile at highway speeds, yet small enough for it to be compact and economical. The transmission and rear axle must be able to distribute the power evenly to all four tires so that the automobile does not become unbalanced or skid. Moreover, it must be efficient in order to maximize the car’s fuel economy and allow for smooth and easy steering.