An excavator is a digging machine with a boom, an arm and a bucket mounted on an upper structure that rotates a full 360 degrees, sitting on tracks or wheels. It digs trenches and footings, moves soil and rock, loads trucks and, with the right attachment, breaks concrete or drills holes. In Australia most people simply call it a digger. Machines under about 6 tonnes, known as mini excavators or mini diggers, are the size you'll see most on house sites, farms and landscaping jobs.
What is an excavator used for?
An excavator is used mainly for digging and moving earth, but the same machine handles a long list of site jobs:
- Digging trenches for water, sewer, power and drainage
- Excavating footings, basements, pools and farm dams
- Loading trucks with soil, rock and spoil
- Backfilling, levelling and shaping ground, often with the blade on a mini excavator
- Breaking rock and concrete with a hydraulic hammer
- Clearing land, pulling stumps and handling logs with a grapple
Builders, plumbers, civil contractors, landscapers, farmers, councils, mines and plant hire companies all run excavators, and each picks a different size for its work. Each of those industries is covered in more detail in our guide to excavator uses across construction, farming and landscaping.
Main parts of an excavator
An excavator has three main sections: the undercarriage it travels on, the upper structure that rotates, and the front end that does the digging. The table shows what each part does.
| Part | What it does |
|---|---|
| Undercarriage (tracks or wheels) | Carries the machine and spreads its weight. Tracks grip soft ground, while wheels travel faster on hard surfaces |
| Slew ring | The large bearing between the undercarriage and the upper structure that lets the cab and boom rotate 360 degrees |
| Upper structure (house) | Holds the engine, hydraulic pumps, fuel and hydraulic tanks and the operator station |
| Counterweight | A heavy block at the rear that balances the boom and the load in the bucket |
| Boom | The main arm, raised and lowered by one or two hydraulic cylinders |
| Arm (stick or dipper) | The second section, which sets how deep and how far the machine digs |
| Bucket | Digs and carries material, and comes off when another attachment goes on |
| Quick hitch | Lets the operator change buckets and attachments without driving the pins out by hand |
| Blade | A dozer-style blade on the front of most mini excavators, for backfilling, levelling and steadying the machine while it digs |
| Cab or canopy | The operator station, with joystick controls and a structure that protects the operator from rollover and falling objects |
Several of these parts wear with use. Tracks, bucket teeth, pins and bushes are the first things to check on any excavator, new or used.
How does an excavator work?
An excavator works by turning engine power into hydraulic pressure. The diesel engine drives hydraulic pumps, which send oil to the cylinders that move the boom, arm and bucket. The same oil powers the track motors and the swing motor that rotates the upper structure.
The operator controls all of this with two joysticks plus travel levers or pedals. Depending on the control pattern, one joystick runs the boom and bucket and the other runs the arm and swing. A skilled operator moves several functions at once in one smooth cycle: dig, lift, swing, dump and swing back.
Digging power comes from two forces. The bucket cylinder curls the bucket to break into the ground, and the arm cylinder pulls the arm in towards the machine to fill it. Spec sheets list these as bucket digging force (often called breakout force) and arm digging force.
Types of excavators
Excavators are grouped first by what they travel on, tracks or wheels, and those are the two main types. Size and arm design split them further.
Crawler excavators
Crawler excavators run on steel or rubber tracks, and they're the type you'll see on most Australian sites. Tracks spread the machine's weight, so a crawler keeps working on soft, wet or uneven ground and stays stable on slopes. The trade-off is travel: a crawler is slow, has to be trucked between sites, and steel tracks mark sealed surfaces.
Wheeled excavators
Wheeled excavators run on rubber tyres, so they travel faster and move along sealed roads and streets without damaging them. That makes them common in roadwork and utility maintenance. A wheeled excavator is less stable when digging, so most use outriggers or a blade to steady the machine before heavy work.
Mini excavators
A mini excavator is a small crawler excavator, usually under about 6 tonnes, built for tight access, house sites, landscaping and farm work. So yes, a mini digger is an excavator, just a smaller one. Most have a blade, and many run on rubber tracks that are kinder to lawns and driveways. Some are built with a short or zero tail swing, which keeps the rear of the machine inside the width of the tracks as it rotates, so you can work close to walls and fences.
Long reach and specialist excavators
Long reach excavators have an extended boom and arm for dredging, deep drains and working across water, at the cost of lifting capacity. At the heavy end, mining excavators and draglines move rock in open-cut mines, while suction excavators use a vacuum instead of a bucket to expose underground services without damaging them.
Excavator sizes: mini, midi and large
Excavator size is measured by operating weight, which is the machine ready to work with fuel, fluids and an operator. Brands draw the lines between classes in different places, so treat these bands as a rough guide.
| Size class | Approximate operating weight | Typical work |
|---|---|---|
| Mini | Under about 6 t | House sites, trenching for services, landscaping, farms, tight access, plant hire fleets |
| Midi | About 6-10 t | Larger residential and commercial sites, civil works, bigger farm jobs |
| Large | Above about 10 t, and well over 80 t for mining machines | Bulk earthworks, roads, civil construction, quarries and mines |
DJJ Equipment sells Yuchai mini excavators from 1.0 t to 5.7 t. Here's how the four models compare on the figures that matter most for size.
| Model | Operating weight | Maximum digging depth | Maximum digging height | Bucket |
|---|---|---|---|---|
| Yuchai E12 | 1.0 t | 1,415 mm | 2,950 mm | 0.02 m³ |
| Yuchai YC10 | 1.0 t | 1,435 mm | 2,755 mm | 0.02 m³ |
| Yuchai U18 | 1.8 t | 2,295 mm | 3,620 mm | 0.05 m³ |
| Yuchai YC60 | 5.7 t | 3,720 mm | 5,740 mm | 0.21 m³ |
The 1 tonne machines suit tight access and small trenches, the U18 digs deeper for house services and landscaping, and the YC60 sits at the top of the mini class for footings, dams and bigger farm jobs. You can compare the full specifications in our range of excavators for sale.
Excavator vs backhoe, skid steer and wheel loader
An excavator is the right machine when the main job is digging, while a backhoe, skid steer or wheel loader each has a different main job. Digger and excavator, by the way, mean the same machine in Australia. The table compares the four.
| Machine | Main job | Strength | Limitation |
|---|---|---|---|
| Excavator | Digging trenches, footings and holes, loading trucks | Digs deepest for its size and rotates 360 degrees without moving the tracks | Slow to travel and not built to carry material around a site |
| Backhoe loader | Digging at the rear, loading at the front | Drives on the road between jobs, with two tools on one machine | The rear arm swings through a limited arc and is less precise than an excavator |
| Skid steer | Loading, grading, carrying and running attachments | Small, quick and turns within its own length | Only digs shallow with a bucket |
| Wheel loader | Scooping, carrying and loading loose material | Moves material quickly across a yard or farm | Not built to dig below ground level |
If your work involves both digging and moving material across a large site, an excavator paired with a loader usually beats asking one machine to do both. On small sites the usual partner is a skid steer, and our guide to what a skid steer is and how it works explains where that machine fits.
Common excavator attachments
Excavator attachments turn the same machine into a breaker, a drill, a grab or a trench digger.
- Buckets: general purpose for digging, narrow trenching buckets for services, and wide mud or batter buckets for clean-up and shaping
- Hydraulic hammer: breaks rock, concrete and asphalt
- Auger: drills holes for posts, piers and trees
- Grapple or thumb: grips logs, rocks and demolition waste
- Ripper: a single tooth that cracks hard or compacted ground before the bucket goes in
- Compaction plate: compacts trench backfill and fill
Every attachment has to match the machine's weight class, hitch and hydraulic flow, so check the attachment's rated range before you buy. Our guide to excavator attachments goes through which tool suits which job.
Quick hitches need the same care. In NSW, SafeWork NSW has phased out semi-automatic quick hitches, and Queensland's regulator recommends fully automatic hitches that don't rely on the operator fitting a safety pin. Check the hitch type on any machine you're buying, new or used.
How to read an excavator spec sheet
An excavator spec sheet tells you how big the machine is, how deep and how far it digs, and how hard it digs. These are the figures to compare:
- Operating weight: decides the size class, the trailer or truck you need and how stable the machine is.
- Maximum digging depth: the deepest point the bucket reaches. Allow a margin beyond your deepest job, because a machine working at its limit is slower and harder to control.
- Maximum digging reach: how far from the machine the bucket can dig at ground level.
- Maximum digging height: how high the bucket teeth reach, which tells you whether the machine can load over the side of a truck or trailer.
- Bucket capacity: how much each pass moves.
- Bucket and arm digging force: measured at the bucket teeth under ISO 6015. Higher figures dig hard ground more easily. A longer arm or a quick hitch adds distance between the pin and the teeth, which reduces the force available.
- Tail swing: whether the rear of the machine stays inside the track width as it rotates.
Here's how the figures work together. Say you need a 1.2 m deep trench for a farm water line and want to load the spoil straight onto a small tipper. The Yuchai YC60 digs to 3,720 mm, about three times the depth you need, and reaches 6,065 mm, so it can work from one side of the trench and swing to a truck parked alongside. A 1 tonne machine would still reach 1.2 m, but it would be close to its 1,415-1,435 mm limit with a bucket about one tenth the size, so a long trench would take far longer.
Do you need a licence to operate an excavator in Australia?
No High Risk Work Licence class covers using an excavator to dig, so there's no national excavator licence card like the forklift licence. That doesn't mean anyone can operate one. Under WHS law, the business must make sure each operator is trained and competent for the machine and the job. Builders and principal contractors usually ask for a recognised excavator training unit or a verification of competency before an operator starts. That training record is what most people mean by an excavator ticket.
Lifting is different. Using an excavator to suspend loads, such as pipes on chains, brings in extra rules. Western Australia, for example, has required a crane class High Risk Work Licence for heavier lifts with earthmoving machinery since 10 August 2025. Check with your state regulator before any lifting work, and only lift with a machine that has a rated lifting point and a load chart.
Before digging anywhere, lodge a free enquiry with Before You Dig Australia to find underground cables and pipes, then confirm their position by hand before the bucket goes in. Striking buried services is one of the most serious risks with any excavator. And never use the bucket to lift or carry people.
How to choose the right excavator
Choose an excavator by the access, depth and transport your jobs need most often, not by the biggest job you might do once a year.
- Access: measure gates, side passages and driveways. A 1 to 2 tonne machine such as the Yuchai U18 suits backyards and tight sites, while a 5 to 6 tonne machine needs open access.
- Depth and reach: match the maximum digging depth to your deepest regular job, with a margin.
- Transport: check the trailer's rating and your vehicle's towing capacity against the machine's weight plus the trailer and attachments.
- Ground and surfaces: rubber tracks for lawns, driveways and sealed areas, steel tracks for rock and demolition.
- Attachments: decide early whether you'll run a hammer, auger or grapple, because the machine needs the right hitch and auxiliary hydraulics.
- Parts and service: check who stocks tracks, filters and wear parts near you, and who comes out when there's a fault.
Service support often decides how a small excavator feels two years in, and our customers' reviews say so in their own words. Dru found plenty of power in a small excavator and rated the service just as highly.
I live 3 hours north of Sydney and they had a mechanic to me the next day when I had a small fault on the machine.
Dru S., Sydney branch customer
Milton, who runs a hire business in Boorowa NSW, put a 1.8 tonne excavator into the dry hire fleet and two years later reported no problems so far. Blake said a mini excavator bought almost two years earlier had performed like an absolute weapon. These stories come from public Google reviews of our Sydney branch, where you can read the full Google reviews of DJJ Equipment Sydney.
An excavator is the right machine when digging is the main job, and a mini excavator covers most house, landscaping and farm work. If your work is mostly carrying and loading, a loader or skid steer may suit you better. To narrow down the size, call DJJ on 1800 355 388 with the job, your digging depth, the narrowest access point and how you'll move the machine. Our team will match a model to it.
