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The Different Parts of an Excavator

21 August | 538 views

The Different Parts of an Excavator

Excavators are essential types of heavy machinery for construction site preparation and other earth-moving equipment. They are primarily used to dig into soft soil and lift and transfer heavy materials like rocks, broken concrete, garbage, cut-down branches, and other debris. If the land intended for a building or real estate development needs to be graded, leveled, or cleared, contractors will need excavators to do so successfully.

Knowing how this machine works makes it easier to understand the parts of an excavator. Read on to learn more about the three main excavator parts, their components, and how they work.


How Many Parts Are There in an Excavator?

There are over 20 parts of an excavator, and most sources will give you 22 distinct components that make up this heavy equipment. However, the exact number of excavator parts varies depending on the type, manufacturer, and model. 

For example, a wheeled excavator doesn’t have tracks but has four wheels instead. It also has a joint-like mechanism that elevates the cab and allows it to rotate 200 degrees. You won’t find this excavator part in a zero-swing excavator.

Read on to learn more about excavator part’s names and functions.

What Are the Main Parts of an Excavator?

This section introduces the different excavator parts’ names and which of the three main parts they belong to: the undercarriage, cab, or arm & boom.


The undercarriage encompasses the lower excavator part responsible for getting the machine from point A to point B. It consists of various moving parts that must always work in sync. The undercarriage’s primary purpose is to move the machine forward and backward (operators must perform a “jump turn” to pivot the machine 90 degrees or more to the left or right). 

Here are the parts of the undercarriage:

  1. Tracks: Excavator tracks made of steel are ideal for heavy-duty excavations and muddy or rocky work sites. Steel-reinforced rubber tracks are also used, often at sites near residential areas. Rubber tracks make much less noise and vibration than steel tracks, so there’s less disturbance to the surrounding community. Tracks absorb the impact from lowering the boom and digging into the ground. Therefore, choosing a suitable material is crucial for extending the life of this particular excavator part.
  2. Wheels: Some excavators have wheels instead of tracks. They offer more flexibility and mobility on-site because operators can quickly turn in any direction and drive forward instead of doing a jump turn.
  3. Rock Guards: These are similar to rock guards for cars and trucks: they protect the tracks from flying rocks and other debris that enter the track frame or get caught between the track chains.
  4. Sprockets: A sprocket is a chain wheel on one end of an excavator track. It has protrusions that insert between the track chain links. It looks and functions like the sprocket in a bicycle, which propels the chain to make the back and front wheels (and, in the case of an excavator, the tracks) move.
  5. Idlers: An idler sits opposite a sprocket on the other end of the track. A large metal wheel guides the tracks as they are propelled from the bottom to the top, back towards the sprocket on the other end of the excavator track frame.
  6. Rollers: The rollers are smaller versions of idlers. They are placed in intervals along the top and bottom of the undercarriage, between the sprocket and idler. Rollers align the chains and keep them moving, propelling the excavator forward.


The cab is the body of the excavator. It houses the operator’s seat and the driving and excavating controls. Depending on the model of the excavator, its cab can turn 360 degrees, allowing operators to dig and remove soil from a specific spot efficiently without having to keep driving back and forth. 

Here are the cab excavator parts’ names and functions:

  1. ROPS: The rollover protective structure or ROPS is a safety feature designed to keep the operator safe if the excavator tips or rolls over. The ROPS is the chassis that encloses the operator’s seat and controls for steering and excavation. It also shelters the driver from the sun and outdoor elements.
  2. Engine: The engine sits right behind the ROPS.
  3. Fuel and Hydraulic Fuel Tanks: These sit on either side of the engine. The fuel tank holds the fuel that powers the machine, while the hydraulic tank houses the components that control an excavator’s hydraulic systems.
  4. Main Control Valve: This valve links the engine with the hydraulic controls. It also regulates oil pressure and powers the arm and boom.
  5. Counterweight: The counterweight is essential for balancing the cab and countering the weight of the hydraulic arm as it lifts and carries heavy loads from one spot to another. The counterweight maintains the center of gravity in the central portion of the cab, preventing the excavator from tipping over when the arm swings or when the bucket is filled to capacity. 

Arm & Boom

The arm and boom are the most prominent parts of an excavator, being at the front and performing the actual digging and earth moving.  

Let’s take a closer look at these excavator parts:

  1. Boom: The boom is the boomerang-shaped protrusion that extends from the cab and holds the arm aloft. The boom is fixed to and moves with the cab as it rotates in place.
  2. Arm: The arm, also called the dipper or stick, is connected to the boom at one end and holds the bucket on the other. It works with the boom to position the bucket and control it to either compress soil, break the ground surface, or dig in and fill the bucket with loosened soil. 
  3. Bucket: The bucket is the giant metal scoop or digger that excavates the ground. Buckets come in different sizes and forms, but the most commonly used ones have “teeth” or “rakes” that dig into the ground.
  4. Hydraulic Cylinders: Three pairs of hydraulic cylinders connect the cab with the boom, the boom with the arm, and the arm with the bucket. The cylinders utilize hydraulic mechanisms to apply heavy force or retract whenever necessary. 


How Many Types of Excavators Are There?

There are seven known types of excavation equipment:

  1. Crawler Excavators: Also referred to as standard or compact excavators, crawler excavators are among the most common types of excavators and are often used in the early stages of site preparation. These have two tracks and a massive, wide cab that anchors the arm, boom, and bucket. The tracks have chain wheels, so they can still descend or scale up uneven terrains without sliding or toppling over despite their size.
  2. Dragline Excavators: These massive excavators use ropes and a hoist coupler to maneuver the bucket instead of an arm and boom. 
  3. Skid Steer Excavators: These are different from the standard excavator because the boom and arm curve towards the back of the cab, sending the bucket overhead instead of having all three – arm, boom, and bucket – in front of the operator.
  4. Long-Reach Excavators: These excavators are comparable to dragline excavators in size. They have extra long arms and booms – some can extend as far as 100 feet horizontally. Long-reach excavators are excellent for digging into areas too narrow for an excavator to drive through.
  5. Zero-Swing Excavators: These massive excavators have a capacity of 42,000 to 48,000 lbs and are excellent for digging trenches and foundations for building constructions. However, despite its size, the zero swing excavator is designed so no part of the cab goes over tracks as it rotates. This makes zero-swing excavators ideal for tight spaces with nearby structures.
  6. Mini Excavators: These excavators have a capacity of 6,000 to 9,000 lbs. They are much less bulky and more agile than their larger counterparts. A mini excavator is ideal for digging or carrying dirt through a tight space because it’s easy to maneuver and occupies little space.
  7. Wheeled Excavators: As previously mentioned, some excavators have wheels instead of tracks. They are agile, versatile, and often used to move soil.

Knowing the different excavator parts’ names and functions should help you decide which models to acquire. However, it’s a good idea to consider renting excavators if you’re looking for a more cost-effective option.

National Dispatching is a one-stop source for heavy machinery and equipment rentals. The company provides well-maintained, highly-functional machines for construction, industrial facilities, and public services. National Dispatching is the company to call if you need earth-moving equipment for rent.

You may call our Central Dispatch at 559-705-2444 or contact us online


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