Basic Parts of a Car and Their Functions


Whether you work on your car or just bring it to the service center, it helps to know the common parts of a car to make educated decisions on vehicle maintenance. Use this guide to help you get started and browse AutoZone’s glossary for more information about different car parts.

Common Car Parts

A woman showing how to install a radiator by sliding it into the front part of her car.
1

Radiator

The radiator is a heat exchanger used to remove heat from the coolant in the cooling system to prevent your vehicle's engine from overheating. Hot coolant is routed through the radiator, where the coolant can exchange heat with the passing air.

For general maintenance on your radiator, check your coolant levels twice a year. Replacing a radiator can take most of the day, but is a doable DIY job. If you need to replace your radiator, use AutoZone's how to guide to get the job done right. Additionally, you should reference your vehicle's repair manual, as each vehicle is slightly different.

2

AC Compressor

The AC Compressor is responsible for pumping coolant throughout your system and starting the process of cooling your car. Without it, the AC system will not work. Summer heats show that your vehicle's AC system is essential, so AutoZone has put together advice on how your AC works and how to recharge your AC if it is not working.

Duralast battery on a shop table in front of an open Nissan Altima.
3

Battery

The battery stores energy in chemical form so it can be released as electricity to run your vehicle's electrical components. Other terms you may run into when talking about a car battery are:

  • Battery Terminal: A means of connecting the battery to the vehicle's electrical system. The three types of battery terminals are post or top, side, and L.
  • Battery Capacity: The energy output of a battery measured in amp/hours.
  • Cold Cranking Amps: Abbreviated CCA, this refers to the amount of current that the battery can supply to the vehicle.
  • Group Size: The group size is just what it sounds like, the size of the battery. Common group sizes are:
    • 24
    • 24F
    • 25
    • 34
    • 35
    • 51
    • 51R
    • 52
    • 58
    • 58R
    • 59
    • 65
  • AGM: This stands for absorbent glass mat, a design in which sulfuric acid is absorbed by a fiberglass mat, making the battery spill-proof and better at holding a charge.

AutoZone wants to make sure you have the right battery for your vehicle, and you have all the trustworthy advice you need when it comes to batteries.

4

Alternator

The alternator is an electricity-generating device that converts mechanical energy to electrical energy in the form of alternating current. It is used to supply power to your vehicle's electrical system along with the battery. The alternator also recharges the battery using mechanical energy generated by the motion of the vehicle's parts.

If you notice that your battery is not working and appears to be swollen, your alternator could have a faulty voltage and has overcharged the battery. Stop into your local AutoZone to help you get back on the road.

New CV axle sitting on a shop table
5

Axle

The front and rear axles are cross members supporting a vehicle where the wheel hubs are attached. Axles are also part of your suspension system and are responsible for sending power to the wheels from the engine through the transmission and differential. They link the wheels to the vehicle and support the weight of each.

CV axles have inner and outer joints with a “boot” on each end. CV axle failures are usually caused by a broken or leaking boot. You can read more about warning signs to tell if your CV axles are going bad in this article.

6

Brakes

A car's brake system is used to stop or slow a vehicle and/or prevent it from moving when stopped or parked. The two most common systems are disc brakes and drum brake systems. Some of the most common disc brake parts include:

  • Caliper: Non-rotational components of disc brakes that straddle the disc and contain hydraulic components forcing the brake pads against the rotor to slow or stop the vehicle. Can be found in the front or rear of a vehicle.
  • Brake Pad: The pad of friction material that is pressed against the disc by the caliper, to slow or stop a vehicle. It is also a term often used for brake lining.
  • Brake Rotor: Disc-shaped component that revolves with hub and wheel. The lining pads are forced against the rotor to provide a friction surface for the brake system, to slow or stop a vehicle.

Drum brake systems mostly consist of a brake drum and shoes. The shoes are covered in friction material that is pressed against the inside of the drum to create friction and slow the vehicle.

Do you hear squeaky brakes and see a brake job in your future? We can help you get started. Whether it is bleeding your brake fluid or knowing which kind of brake pad to buy, AutoZone has what you need to get the job done, DIY style.

7

Shock Absorbers (Shocks and Struts)

Shock Absorbers are a hydraulic device used at each wheel of the suspension system to help control the up, down, and rolling motion of a car body by dampening the oscillations or jounce of the springs when the car goes over bumps, thereby contributing to vehicle safety and passenger comfort. Also referred to as a shock or strut, depending on which the vehicle is equipped with.

A typical shock absorber has three functions:

  • Dampen the effect of spring oscillation in order to control the ride stabilization of a vehicle
  • Control body sway
  • Reduce the tendency of a tire tread to lift off the road surface (a problem often caused by static unbalance)
8

Transmission

The transmission is a gearing device of a vehicle that provides variable ratios between the engine output and the differential input. Automotive transmissions are more complex than bicycle transmissions, but they play the same basic function, allowing the driver (or engine computer) to select smaller or larger gears to optimize driving conditions without working the engine too hard. There are two types of transmission:

  • Automatic Transmission: A transmission in which gear ratios are changed automatically using automatic transmission fluid (ATF). Shifts are controlled by the engine computer. Some automatic transmissions are continuously variable (CVT), or shiftless transmissions which can change seamlessly through a continuous range of effective gear ratios.
  • Manual Transmission: A manually shifted gearing device in the power train that allows variation on the relationship between engine speed and road speed.
9

Catalytic Converter

The catalytic converter is an automotive exhaust-system component, made of stainless steel, containing a catalyst to reduce oxides of nitrogen (NOX), and/or hydrocarbon (HC), and carbon monoxide (CO), in tailpipe emissions. It is used to remove pollutants and make exhaust gasses less harmful to the environment.

10

Muffler

The muffler comes just before the end of the exhaust pipe and is responsible for reducing the noise emitted by the exhaust system. It restricts exhaust gas flow, which leads to a quieter ride. Some mufflers restrict gas flow more or less, which results in quieter or louder exhaust noise respectively.

11

Tailpipe

The tailpipe is the pipe that carries exhaust fumes from the muffler or catalytic converter to the rear of the vehicle.

12

Fuel Tank

A storage tank for gasoline that powers your vehicle.

Advice, how-to guides, and car care information featured on AutoZone.com and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

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