This story was created for the Google Expeditions project by Vida Systems, now available on Google Arts & Culture.
The vast majority of cars run on internal combustion engines but the future of cars is electric. Regardless of what’s under the hood, cars work on the same basic principles.
Forces and basic parts
Most cars today are built with a similar shape and all have the same basic components that the very first cars had when they were developed. In order for a car to move, it needs to overcome some basic forces, and it employs an engine to do so.
There are 3 basic forces that act against a car’s movement. These are gravity, which pulls down on the car; air resistance, which pushes against the car; and friction between the tires and the ground.
All cars have chassis. This is the framework around which the car is built, and it is very much like a skeleton. The chassis needs to be strong, as well as lightweight.
All cars have seats to transport the driver and usually at least 1 passenger. The largest passenger vehicles, buses, can hold hundreds of travelers at a time.
All cars have a wheel which is used by the driver to control and turn the vehicle. The steering wheel can be on the right side or the left side of the car.
Every car has an engine, the component which makes it able to actually move and go. This expedition will be focusing primarily on the internal combustion engine.
Chassis are the framework onto which other parts of the car are connected. In older cars, the chassis only includes the bottom framework—the car’s body is usually not considered part of the chassis.
In newer cars, the body and the chassis are integrated into a “unibody.” A well-designed chassis will help protect the driver and passengers in a collision.
Chassis act as an anchor point for many important car components. The wheels, suspension, and brake system of modern vehicles are all included within the chassis.
Chassis are constructed out of a few different materials depending on the car model. Most often chassis are made out of carbon steel and aluminum alloys. These materials are both relatively lightweight and very strong.
Importantly the design of the chassis needs to take into account the final weight of the vehicle. It should be strong enough to provide the required support.
The chassis needs to be rigid enough to handle uneven road surfaces and torque from the engine and transmission. If it is too flexible, the car will be difficult to steer and control.
The car’s engine is arguably the most important part of a car. The engine overcomes the forces working against movement. Essentially it does this by converting fuel into kinetic energy. The simplest way to do this is to burn fuel using an internal combustion engine.
The mechanics behind this engine are simple. Fuel is literally exploded inside the engine. The force of the explosion makes other parts of the engine move.
In fact, combustion engines explode little bits of fuel hundreds of times per minute in order to move the car. The spark plug provides the ignition source of these explosions.
Each explosion causes the pistons mounted on the engine to be pushed outward. This action then turns the crankshaft, transforming the heat energy into kinetic energy.
Different models of cars may have slightly different engine configurations. Most cars have a 4-cylinder design, while some cars have 6 or 8 cylinders. More cylinders result in more power.
The transmission of a car acts as the intermediary between the car engine and the wheels. Just like a bicycle, a car has a number of gears which determines how fast the car can travel.
For example, in first gear the transmission will only allow the wheels to turn at around 30 miles per hour, even if the accelerator is pressed down to the floor.
Without the transmission a car wouldn't work. Pistons need to move 1,000 times per minute. If the engine connected directly to the wheels, the car would instantly move on start up, and stop only if the engine was turned off.
Each gear turns a different wheel within the transmission. The wheel for first gear is the smallest and the wheel sizes become larger with higher gears, the same as a bicycle.
Automatic transmissions choose when the car will shift gears, ensuring the engine doesn’t run at too high of an rpm rate (revolutions per minute). A very high rate could kill the engine.
Automatic transmissions have a torque converter, which contains fluid. This part continues to spin even when the car is stopped, allowing the engine to keep above the minimum rpm at all times.
Brakes and suspension
The role of the suspension within a car is to maximize the friction between the wheels and the ground while providing a comfortable experience for the passengers and driver. The brakes physically slow a car down by converting kinetic energy into heat energy.
Roads are not perfectly smooth, and the wheels of a car often leave the road while traveling over bumps. The suspension system absorbs the impact of landing by using strong springs.
The suspension doesn’t rely on the springs alone, they also have shock absorbers. These oil-filled cylinders slow down the vibrations created by the springs, making the ride more comfortable for the car’s passengers.
In order to stop a car, hydraulic brakes are used. When the brake pedal is compressed, it sends fluid into a cylinder. This fluid pushes a piston.
The piston then pushes 2 brake pads (on either side of the brake disc), creating a large amount of friction and heat. This stops the axle from turning and stops the wheels spinning.
The future of cars
The reign of the internal combustion engine will soon be over, and the next generation of vehicles will be electric. Electric motor will be quieter, far more efficient to run, and have less moving parts than a traditional engine.
Today’s electric cars are more powerful than most of the best internal combustion engine cars.
Electric motor generate motion directly, without creating heat. The driveshaft moves by the use of magnets, rather than having metal components rubbing against each other.
Electric cars have no transmissions, no oil tanks, no pistons. The entire motor may be about the size of a large watermelon, with only 1 moving part.
Electric cars use regenerative braking. This means that when the wheels are forced to stop, they turn a motor, which acts as a generator and recharges the batteries.
Batteries, which store the electricity, make up the bulk of the chassis. They also account for a significant percentage of the weight of a car with an electric motor.