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Why Are Carbon Brushes Important?

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electric motor

electric motor

You may be familiar with the carbon brushes, especially if you have an electric motor that requires maintenance. But the question is, do you really know what these carbon brushes and how important they are?

A carbon brush is a little square of carbon that delivers a current to the electric motor. You can say that it's ultimately beneficial for the electric motor since it won’t function without it. But there's more to it than this simple definition.

By the end of this article, you'll have a deeper understanding of carbon brushes.

How Carbon Brushes Work

Although carbon brushes are essential components in an electric motor, it's surprising that many people are frequently discounting them. That's because not everyone knows how it works.

You can also call carbon brushes motor brushes, which are the small portion of the motor that administers electric current between the rotor (rotating wires) and stator (stationary wires) of a generator or motor. 

Commonly, a motor has two or more carbon brushes to facilitate the transmission of electrical current. These brushes are classified into five brush grades. Each of these brushes in the category is applicable for various types of motors and operations. Thus, making it abundant in the market. With such, you can find many great deals and variations in many reputable websites, such as Top Deals Online.


Different Grade Classifications Of Carbon Brushes  

Originally, brushes were built from copper. However, as time passes, carbon becomes the more adopted material for a motor brush. This is due to its excellent contact resistance, ability to oppose arcing, and minimal friction.

With such, you can use any of the four different brush-grade families of carbon brushes:

  • Metal graphite: The metal graphite carbon brush is built by mixing graphite with thin metal powders, like lead, copper, tin, and silver. Because of its minimal resistivity, many use this brush in countless ways.

You can see metal graphite carbon brushes in welding generators, forklift truck motors, plating generators, battery chargers, DC machines, and slip rings with great brush current consistencies.

  • Graphite: Defined by the layer of materials, this type of brush is fabricated by combining either synthetic or natural graphite with pitch or resin.

You can find these brushes available in slip rings and commutators. Moreover, graphite carbon brush is most suitable for contaminated environments because of its low porous and high-density characteristics.

  • Electrographites: The electrographite carbon brush is built with extreme temperatures. This is the reason why they're considered to be longer-lasting and best for commutators.

This type of carbon brush is treated with either inorganic or organic materials to support its durability. Moreover, it's best when it’s used in various operating settings, including environments with low humidity and extreme temperatures.

  • Carbon graphite: The carbon-graphite brush is one of the first designed carbon brushes. This brush is best for traditional and slower motors with the highest surface speeds of 4,000 feet per minute.

Moreover, it's applied in both metal contacts and bases. You can hardly see this type of brush in commutators since it produces high friction.

motor parts

motor parts

Significance Of Carbon Brushes

Commonly found in motors, alternators, and generators, carbon brushes are also used for different applications, such as the following:


1. Automotive Applications

Overall, cars utilize auxiliary and tiny carbon brushes for alternators, DC motors, and starters. Alternators play an essential role as they're responsible for the conversion of mechanical energy to electrical energy. They're normally composed of wire-coiled roots that create a magnetic field when the current flows through them. The wire coils in the alternators receive current through the application of carbon brushed.

Moreover, most passenger vehicles, motorcycles, trucks, and oil-and-diesel-fueled vehicles have carbon brushes. Carbon brushes that went through a special process are found in the steering wheels and contacts for the car's airbags.

In many cases, these brushes are durable, and you can easily replace them if they’ve already deteriorated.

repair electric motor

repair electric motor

2. Industrial Uses

Carbon brushes used for industrial purposes are found in the large commutator equipment. These include AC and DC motors, windmills, traction motors, cement mills, hydropower stations, slip-ring rotors, paper, hydropower stations, steel, and turbo-generators. 

Furthermore, different industries can utilize carbon brushes for running battery-driven vehicles, cable cars, and trolleybuses. Even construction automobiles, such as forklift trucks and cranes, use carbon brushes. That's because carbon brushes for industrial purposes are commonly designed to endure extreme temperatures.


3. Household Uses

Not only can you find carbon brushes in industrial and automotive industries, but also in your homes. You can find carbon brushes used in common household stuff such as power tools, gardening equipment, and office equipment.

Also, popular applications of these brushes are on your electrical appliances, like vacuum cleaner turbines, washing machines, as well as hair and hand dryers.

Carbon brushes that are used for household items are quite smaller than the carbon brushes used in industrial and automotive.

motor partss

motor partss

Carbon Brushes In Your Home

Since you can use carbon brushes in many applications, you should also consider these top two reasons aside from their many uses:

  • Exceptional Conductivity

One of the most remarkable reasons for using carbon brushes for any application is their superior and reliable conductivity. Since it essentially possesses high conductivity, these brushes become ideal for big industrial projects and operating appliances in your house.

Particularly, carbon brushes integrated with lead are best for vacuum cleaners since they have minor cross-sectors that can clean despite a lowered input power.


  • Excellent Self-Lubrication And Abrasion Resistance

Carbon is characterized by high resistance to abrasion because of its two significant properties: the layered crystal structure of the carbon and other electrical elements.

Since carbon has an abrasion-resistance feature, it's economical and easy to use for machines and home appliances. Moreover, you can expect carbon brushes to last longer than other kinds of brushes. This means that it can provide extended services for various household uses.



Carbon brushes may appear insignificant to you as they’re normally in a small square that contains carbon. But after going through the roles and importance of carbon brushes, you now know that they're more than their looks. Carbon brushes are powerful, whether for household, automotive, or industrial use.