Parts of a Car

On average, a car has around 30,000 individual components. That's counting every screw, tube and rubber seal. But even if you focus on larger parts, such as the intake and exhaust manifold, crankshaft and camshaft, plenty of bits go into making a vehicle work. Let's explore the key components.

How does a car’s engine work?

The engine is where combustion takes place, releasing energy translated to piston movement and, from there, to the mechanical force that makes the wheels move. Let's look at the parts that go into making all that work.

The cylinder block and pistons
The cylinder block consists of several cylinders, where carefully controlled explosions occur as a mixture of fuel and air is ignited. Each explosion causes the air pressure in the cylinder to increase for a moment, forcing that cylinder's piston to move. The energy is transferred to the transmission, which converts the torque from the pistons into driveshaft torque, the force that makes your car move. 

Spark plugs
Spark plugs are one of the final parts of what goes into making combustion happen. They're cylindrical components with an electrode at one end. When electricity is sent through a spark plug, it generates a spark that jumps from that electrode to the center conductor. When this happens with fuel and air in the cylinder, the fuel ignites.

Cylinder head and valves
Rather than being fed a constant stream of fuel, the cylinder block is given a carefully paced and measured mixture of air and fuel. The cylinder head sits on top of the cylinder block and has valves that open and close at precisely timed intervals to ensure the flow of air and fuel into the cylinders is properly balanced.

The crankshaft and camshaft
The crankshaft is a rotating shaft connected to the pistons. When the pistons move up and down, the crankshaft translates this into rotational motion. Meanwhile, the camshaft helps keep the engine's valves in sync so the controlled explosions happen at the right time to extract a steady stream of kinetic energy from the fuel.

Fuel: The lifeblood of a car

Modern cars use a fuel-injection system that sprays fuel directly into the intake manifold or combustion chamber. The system ensures the chamber always has the right amount of fuel and that it's mixed with the right amount of air.

The fuel pump
A fuel pump takes fuel from the tank and feeds it to the injectors so they always have a steady supply of gas available. The pump also has a return line, so any fuel not immediately used is circulated back into the tank.

The catalytic converter
Burning fuel produces some harmful emissions, including:

• Carbon monoxide

• Nitrogen oxides

• Hydrocarbons

Catalytic converters work by passing exhaust gases over a honeycomb structure made of precious metals, which act as a catalyst, bringing about reactions that turn those unwanted substances into safer chemicals. These parts first came into use in the 1970s. Today, regulations vary across the world, but in general, all modern cars are either required to be equipped with one or to use some other technology to ensure they meet emissions standards.

Mufflers and resonators
The combustion process and the sheer number of moving parts in an engine mean cars and trucks can be pretty noisy. To mitigate that noise, most vehicles have a muffler and a resonator fitted. The muffler is the big cylinder you see under a car, just before the exhaust pipe. It doesn't look like much from the outside, but inside, there are several chambers and baffles that dissipate sound energy, making the exhaust quieter.

A resonator serves a similar purpose. It's a straight pipe or chamber that reflects sound waves back toward the exhaust gases, helping cancel out some of the noise.

If you've ever noticed a car that looked like a fairly standard make or model but sounded incredibly loud and rumbly, there's a high chance the car's exhaust had been modified. Many states have noise control laws that prohibit people from running a vehicle without a muffler or fitting devices to amplify the noise, but car enthusiasts often try to skirt those laws with aftermarket modifications.

The transmission and driveshaft

All internal combustion engines use transmissions to route torque from the crankshaft to the wheels. Whether a traditional automatic, a do-it-yourself manual gearbox or a continuously variable automatic transmission (CVT), all transmissions are necessary to control the vehicle’s speed through gear changes and to change the car’s direction. 

Automatic transmission 
Aside from choosing park, reverse, neutral and drive, an automatic transmission does all the shifting work for the driver. This transmission type uses a torque converter to connect and disconnect the engine from the driveline to facilitate changing gears. Automatic transmissions use hydraulics, electronics and a control module to sense the car’s speed compared to how fast the engine is spinning and shift accordingly. Dual-clutch automatic transmissions in high-performance cars use two clutches set with varying gears that work together — one’s ready after the other — to snap off rapid shifts. 

Manual transmission 
A manual transmission requires the driver to select the proper gear with a stick shift and engage or disengage the clutch with their left foot and clutch pedal. Mechanically, a flywheel, pressure plate and clutch work together to disconnect and connect the engine from the transmission for shifting gears. Automated manual transmissions or paddle shifters are not manual transmissions, but automatic gearboxes controlled by computers.

Continuously variable transmission (CVT)
You’ll find most continuously variable automatic transmissions (CVTs) in smaller economy cars, compact SUVs and even some hybrids. This type of automatic transmission uses a belt or chain connected to a primary small drive and a secondary large driven clutch to continuously change gear ratios. The pulley system adjusts based on wheel and engine speeds and can raise or lower the speed simultaneously to save fuel. 

Driveshaft and differential 
Once the transmission controls the engine speed, the torque must reach the wheels. So, it gets routed from the transmission to the driveshaft, which spins the differential and then the wheels. So that the tires don’t rub unevenly when turning (think of why a track runner in lane one lines up behind everyone), the differential uses gears to split torque to the wheels when the car’s turning. Limited-slip differentials shift even more torque to the wheel with the most grip, improving handling characteristics. Locking differentials on trucks and SUVs split torque evenly between wheels on a given axle to improve traction in slippery situations. 

Cooling and lubrication 

Cars can get hot. When combustion occurs in the cylinders, heat is distributed throughout the engine block and into the exhaust. Friction from moving parts can also lead to overheating of vital system functions. To prevent your car from overheating and putting you in a dangerous situation, cars have cooling systems and lubricants to regulate temperatures and ensure that all the moving parts work properly.

Radiators and fans
A radiator removes heat from the coolant that’s circulating the engine to keep it cool. Fans draw air through the radiator and over the engine to help remove as much heat as possible. 

Oil, oil pump and oil filter
Oil circulates through the engine to keep all its moving parts lubricated. The transmission and differential also use fluids to keep them cool. The oil pump draws oil from the oil pan and forces it through the engine while an oil filter removes contaminants. You’ll need to change the oil and filter routinely at the suggested intervals in the owner’s manual. 

Water pump
A car’s engine gets extremely hot. Safe operating temperatures can reach over 200 degrees Fahrenheit. To prevent overheating, a water pump circulates coolant with a high thermal capacity through hoses to the radiator and engine. 

Electrical systems

Battery and alternator
An internal combustion engine runs its electrical components using a battery, which is charged by the alternator when the vehicle is idling or in motion. The alternator also supplies power to your vehicle’s electrical systems, such as the headlights, electric steering, infotainment systems, power windows, heated seats and sound systems. 

Braking system

Brake pads
The brake pads used in today's cars are made of a ceramic or composite material that's quite hard-wearing. These pads clamp onto metal discs connected to the wheels. When the driver applies the brakes, the pads come into contact with the wheel, and the friction generated by the pads slows the vehicle down. 

Brake pedal
The brake pedal inside the car allows the driver to control the brakes with their foot. When the driver presses the pedal, hydraulic pressure is created, which is transmitted down the brake lines to trigger the movement of the pads. Modern vehicles use a combination of vacuum and hydraulic technologies to amplify the pressure the driver puts onto the brake, enabling them to bring their car to a stop with only gentle foot pressure.

Suspension system
If it weren’t for suspension, your car would ride like a wagon on the Oregon Trail. Roads aren’t flat, so a combination of shocks and springs soaks up bumps to make sure you and your passengers don’t get too carsick. 

Shocks and struts
Shocks soak up bumps in the road, while struts support the vehicle's weight and keep motion in check. High-performance vehicles like the Chevrolet Corvette and Porsche 911, along with luxury sedans and SUVs, use adaptive shocks that can soften or stiffen the ride for distinct handling characteristics. Big off-road trucks and SUVs will use heavy-duty leaf or coil springs to support heavy loads.  

Control arms
Control arms connect the wheels to the frame and allow the wheel to move up and down with the rest of the suspension system to keep the tires in contact with the road. They also help with the wheels’ alignment so they don’t rub and wear unevenly. 

Wheels and tires

Wheels and tires come in all shapes and sizes and numerous types of tread patterns for snow and rain or highway, off-road, or track use. A tire’s sidewall gives plenty of information on the type and size of the tire. You can see a full rundown of a tire’s sidewall here. 

How to read a tire’s size

There are three numbers on a tire’s sidewall that will tell you its size. The first is the width, say 265, in millimeters (mm). The second numeral indicates the height of the sidewall expressed as a percentage of the tire's width (this is also called the tire aspect ratio). The last number marks the wheel’s diameter in inches, so if you have a 17-inch wheel, the tire size might read 265/75/R17. That means that the width of the tire is 265 mm, the height is 75% of the width, and it’s wrapped on a 17-inch wheel.