Excavators are some of the most recognizable and versatile machines on a construction site.
You can find them digging foundations, trenching for utilities, moving dirt, demolishing buildings, clearing land, working in mines, and performing countless other jobs.
But what exactly is an excavator, how does it work, and what type should you use for your project?
This guide explains everything you need to know about excavators, from the basic components to the different types, sizes, attachments, and common uses.
What Is an Excavator?
An excavator is a heavy construction machine designed primarily for digging, lifting, and moving material.
A typical excavator consists of several major components:
- Undercarriage
- Tracks or wheels
- House
- Engine
- Boom
- Stick
- Bucket
- Hydraulic system
- Operator cab
One of the things that makes an excavator so useful is its ability to rotate the upper portion of the machine while the undercarriage remains in place.
Most tracked excavators can rotate approximately 360 degrees, allowing the operator to work across a large area without constantly repositioning the entire machine.
How Does an Excavator Work?
Modern excavators rely heavily on hydraulic systems.
The engine powers hydraulic pumps, which pressurize hydraulic fluid. That hydraulic pressure is then used to move the machine’s cylinders and motors.
The operator controls these functions from the cab.
For example, when the operator moves a control to raise the boom, hydraulic fluid is directed to the appropriate cylinder, causing it to extend.
The same basic principle allows the operator to:
- Raise and lower the boom
- Move the stick
- Curl the bucket
- Rotate the house
- Drive the tracks
- Operate attachments
This hydraulic design gives excavators tremendous digging and lifting capability relative to their size.
The Main Parts of an Excavator
1. Undercarriage
The undercarriage is the lower portion of a tracked excavator.
It includes components such as:
- Track chains
- Track shoes
- Rollers
- Idlers
- Sprockets
- Final drives
The undercarriage supports the machine and allows it to travel across the job site.
Because these components experience substantial wear, the undercarriage is one of the most important things to inspect when buying a used excavator.
2. House
The house is the upper structure of the excavator.
It contains many of the machine’s major components, including the engine, hydraulic system, counterweight, and operator cab.
The house sits on a swing bearing that allows it to rotate relative to the undercarriage.
3. Boom
The boom is the first major arm extending from the machine.
It provides the primary lifting and positioning movement for the front attachment.
4. Stick
The stick connects the boom to the bucket or other attachment.
Moving the stick allows the operator to extend the machine’s reach and control how far the attachment moves from the excavator.
5. Bucket
The bucket is probably the most recognizable excavator attachment.
Different buckets are designed for different materials and applications.
Examples include:
- Digging buckets
- Heavy-duty buckets
- Rock buckets
- Grading buckets
- Ditch-cleaning buckets
The correct bucket can have a significant effect on productivity.
Types of Excavators
There isn’t just one type of excavator.
Different designs are built for different jobs.
Mini Excavators
Mini excavators are compact machines designed for work where space is limited.
They’re commonly used for:
- Landscaping
- Residential construction
- Utility work
- Drainage
- Small foundations
- Trenching
Their compact size makes them easier to transport and maneuver than larger excavators.
Standard Excavators
Standard excavators are the machines most people picture when they think about excavators.
They’re available in many sizes and are commonly used for:
- Excavation
- Site preparation
- Utility installation
- Road construction
- Foundation work
- Material handling
Long-Reach Excavators
Long-reach excavators use extended booms and sticks to provide additional reach.
They’re useful for jobs where the operator needs to work farther away from the machine, such as certain demolition, dredging, and slope applications.
Wheeled Excavators
Instead of tracks, wheeled excavators use tires.
They’re particularly useful when machines need to travel frequently on paved roads or hard surfaces.
Dragline Excavators
Draglines are specialized machines primarily associated with very large-scale excavation and mining operations.
They use a different digging system involving a bucket suspended from cables rather than the conventional hydraulic boom-and-bucket arrangement found on most modern excavators.
What Are Excavators Used For?
Excavators can perform a huge variety of jobs.
Digging
This is their most obvious application.
Excavators are commonly used to dig:
- Foundations
- Trenches
- Basements
- Ponds
- Drainage systems
- Utility lines
Demolition
With the right attachments, excavators can be used to demolish structures and process debris.
Specialized demolition machines can also be equipped with extended-reach configurations for working on taller structures.
Material Handling
Excavators can move materials around a job site using buckets, grapples, lifting accessories, and other attachments.
Landscaping
Smaller excavators are popular with landscapers because they can move significant amounts of soil while working in relatively confined spaces.
Forestry and Land Clearing
Specialized attachments can allow excavators to clear vegetation, process material, and prepare land for development.
Excavator Attachments
One of the biggest advantages of an excavator is that the bucket doesn’t have to be its only attachment.
Depending on the machine and hydraulic configuration, an excavator can use attachments such as:
- Hydraulic breakers
- Augers
- Grapples
- Compactors
- Thumbs
- Shears
- Rakes
- Tilt buckets
- Specialized demolition tools
This can turn a single excavator into a highly versatile machine.
How Do You Choose the Right Excavator?
Choosing an excavator starts with understanding the job.
Consider:
Machine Size
A larger excavator generally provides more digging and lifting capability, but it also requires more transportation capacity and working space.
Digging Depth
If you’re digging deep trenches or foundations, make sure the machine has sufficient maximum digging depth.
Reach
Consider how far you need the machine to reach while still maintaining the required performance.
Operating Weight
Operating weight affects transportation, ground pressure, and the type of projects where the machine can be used.
Hydraulic Capacity
If you plan to run hydraulic attachments such as breakers or augers, make sure the excavator has the hydraulic flow and pressure required by the attachment.
Transportation
Don’t forget about getting the machine to the job site.
A machine that is perfect for the job may still create logistical problems if it requires specialized transportation.
CAT vs. Komatsu vs. Other Brands
Some of the major excavator manufacturers include:
- Caterpillar
- Komatsu
- John Deere
- Volvo
- Hitachi
- Kobelco
- Hyundai
- Liebherr
Each manufacturer offers different models, sizes, technologies, and configurations.
Rather than asking which brand is universally the best, compare the specific machine, dealer support, parts availability, purchase price, operating costs, and expected resale value.
New vs. Used Excavators
Buying new gives you the advantages of newer technology, a new-machine warranty, and no previous operating history.
Buying used can significantly reduce the initial purchase price.
However, used equipment requires careful inspection.
When looking at a used excavator, pay particular attention to:
- Operating hours
- Maintenance records
- Undercarriage
- Hydraulic system
- Engine
- Swing bearing
- Pins and bushings
- Tracks
- Attachments
- Signs of structural damage
A professional inspection can be worthwhile before making a major purchase.
Final Thoughts
Excavators are among the most versatile machines in construction.
From compact mini excavators working in backyards to enormous machines used in mining operations, there’s an excavator designed for almost every type of excavation job.
The key is choosing the right combination of machine size, configuration, attachment, and capabilities for the work you’re actually doing.
As you research construction equipment, don’t just compare brands. Compare the machine’s specifications, operating costs, service requirements, dealer support, and long-term value.
The right excavator isn’t necessarily the biggest or most expensive one. It’s the one that gets your job done efficiently and economically.