What Are the Three Major Parts of an Excavator?

Back to Blog

Excavators are powerful digging machines that are standard equipment at construction sites. Whether you’re looking to add an excavator to your fleet or learning how to operate one productively and safely, it’s helpful to know about the three primary components and their functions.


The undercarriage is the bottom portion of the excavator. Its purpose is to propel and support the machine while playing a vital role in its overall performance and stability. 

Examples of the other excavator parts you’ll find in the undercarriage include:

  • Tracks: This part, which can consist of steel or steel-reinforced rubber, enables the machine to move over various terrain types.
  • Sprockets: These mechanisms function like a bicycle sprocket to move the track chains that propel the excavator.
  • Rollers: The sets of top and bottom rollers move between the sprocket and idler to enable the chains’ functionality.
  • Idlers: These large metal wheels guide the tracks and ensure that the tracks, sprockets and rollers operate smoothly.


The cab is the excavator’s “nerve center.” It’s where the operators sit as they run the machine, and it provides access to all the primary controls. Depending on the model, the cab can rotate 360 degrees for maximum visibility. 

The cab includes several important safety features, such as the rollover protection structure (ROPS) and the counterweight to keep the machine from rolling or tipping. Tanks containing the fluid required for the various hydraulic mechanisms that control many of the machine’s functions are usually inside the cab. The engine is typically installed near the cab for easy access. 

Boom and Arm

The boom and arm work together to perform the digging functions. The boom attaches to the excavator’s cab and controls the movement of the connected arm. The latter component holds and manipulates the bucket that performs the digging tasks.

Operators can choose from multiple bucket options to meet each project’s unique digging requirements. They can also replace the bucket with various attachments to utilize the excavator’s versatility. Examples include augers, hammers, breakers, mowers and brushcutters, pipelayers, and tree shears. 

Learn More From Gregory Poole

At Gregory Poole, we’ve been offering high-quality Cat® excavators to businesses throughout eastern North Carolina since 1951. We have the experience and expertise to answer all your excavator questions and help you choose the best machines for your applications and budget. If you’re interested in learning about more parts of an excavator, learn about 10 common parts of an excavator.

Contact us online to learn more. 

Learn More From Gregory Poole