Automobiles, which are self-propelled vehicles, are one of the most important inventions in modern times. They have transformed the way we live, work and play. They have also had a profound influence on society and the environment. Almost every industry, from agriculture and logging to the manufacturing and distribution of goods, has been affected by automobiles. Moreover, entire cities have been designed around the power of automobiles, and most societies have restructured themselves around the convenience of rapid, long-distance travel that cars provide.
Having your own car gives you freedom and independence. Whether you are running late for your bus or want to drop your children at school on time, your own vehicle will get you there. Automobiles are faster than walking and riding a bike, can carry more luggage, and can go places that buses, trains and bicycles cannot. However, they are expensive to operate and emit harmful gases.
The most important part of an automobile is its engine, which uses fuel—gasoline, diesel or kerosene—to produce mechanical energy to turn the wheels. The engine’s parts must be lubricated to reduce friction and prevent damage from heat. The lubrication system carries oil from the crankcase through a series of passages and holes to all the moving parts in the engine. The oil also carries away heat from the engine.
Other parts of an automobile include the suspension and steering systems, which keep the car in contact with the road; the braking system, which slows the car down when the brake pedal is depressed; and the body, which provides comfort and protection from the elements for passengers. The chassis, which is analogous to the skeletal structure in the human body, supports these and other systems.