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Tim Forestell
September 18, 2020

Excavators are powerful machines that come in many different sizes. With their variety of attachments and the choice between wheeled or tracked machines, excavators are being used for all types of construction work. While there’s a lot of information about the history, use and manufacturers of excavators out there, what exactly makes an excavator an excavator?

The 3 Key Parts of an Excavator

Whatever you choose to call them, there are three key sections to an excavator. Some call this the undercarriage, house and boom and others use terms like attachment, base frame and undercarriage or boom, upper structure and lower structure. Whatever words you use, it’s clear that there are three main sections to be aware of when talking about an excavator.

Diagram of a Caterpillar 6015B Hydraulic Excavator. Image borrowed from RitchieSpecs.

The Undercarriage

The undercarriage of an excavator encompasses the tracks, track frame, and hydraulic motor and gearing. Wheeled excavators would have wheels and an axle instead of a track and track frame but the basics stay the same. Any type of blade or dozer attachment would also be considered a part of the undercarriage.

Maintaining the Undercarriage

Since the undercarriage literally supports the machine for all jobs it’s important to maintain and take proper care of it. Failure to do so can lead to breakdowns and other mechanical problems that can take the machine off rotation. 

Cleaning and removing any debris from the undercarriage after each shift will help keep all the moving parts functioning properly. This is especially important in cooler climates because frozen debris can wear away at bolts, fasteners and other connections in the undercarriage. There are many moving parts in this part of an excavator and keeping everything moving clear of debris is important. 

Undercarriages should also be a standard part of daily inspections. Track shoes, chains, bolts and tensions as well as rock guards and drive motors and sprockets should be checked every day. Following best practices for driving and operating will also help to maintain the undercarriage of an excavator. Take wide turns, minimize time on slopes, using the proper grouser, avoiding harsh terrain and minimizing excessive spinning will all help with the upkeep of an undercarriage.

The House

The house is most recognized as the cab of the excavator. Some separate the cab as a completely separate part of an excavator and some group it together with the house. Although the operating cab is the more prominent feature, there are other parts to the house that are just as important. The house also features the base frame, counterweight, holds the fuel and engine as well as the hydraulic oil and other liquids needed to keep the machine operating smoothly.

Image borrowed from Phillip Hengst.

Counterweights on Excavators

Traditional counterweights used to be a long or “conventional” weights that hung off the backside of the machine. The weights provided additional strength and digging ability to the front attachment and boom. In 1993, Yanmar introduced the first-ever Zero Tail Swing counterweight. This invention revolutionized the use of excavators by shortening the space in which the machine could operate. Today, zero tail swing counterweights are considered a standard in the industry.

The 360° Excavator Power

The 360° capabilities of an excavator are achieved by the house sitting on a swivel pin. Hydraulic power and gears give the machine the ability to swivel in all directions. The zero tail swing invention by Yanmar allowed operators to take full advantage of this design. The full circle rotation capabilities of the excavator are part of what makes it such a powerful machine.

The Arm, Boom or Attachment of an Excavator

Whether you look at the boom or arm as one part and attachments as another, they both rely on each other and are connected. This is why the arm of the excavator is often seen as the third part of the machine and they are not separated. In general, the arm is made up of a boom, a stick and the attachment. 

There are a few different types of booms that can be found on excavators. The most common is the mono boom – the arm bends in one direction only. There are knuckle booms or hinge booms that allow for alternative rotation and movement. These different boom types allow operators to dig exactly what they need to dig no matter what type of environment they are working in.

Attachments of Excavators

There are so many different types of attachments for excavators that it’s almost impossible to name them all. Bucket attachments alone have varieties such as ditch buckets, heavy-duty buckets, cleaning buckets, tilt buckets, rock buckets and grading buckets. 

The best way to choose an excavator attachment is to know exactly what type of project you’re working on and what the best tool is for the job. The good thing about there being so many different types of attachments is that there will be the perfect attachment for your job.

Image borrowed from Open PR

The Importance of Understanding the Makeup of an Excavator

Knowing the different parts and makeup of a machine can help you identify issues that may come up on the job. It’s also a valuable part of recognizing how the machine comes together to do its job. The undercarriage holds the machine together while the house supports the operator and arm as the attachment does its job. Each of these three key sections of the excavator has a part to play but come together to give the industry one powerful machine.

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Tim Forestell
Tim Forestell is one of DOZR’s co-founders and CCO. Tim got started in the industry as VP Operations for Forestell Landscaping before founding DOZR with Kevin and Erin. Aside from the amazing team at DOZR, his favourite thing about DOZR are the customers. Working with DOZR renters every day gives him a peek at the evolution of different projects and hearing stories about projects being developed from start to finish.
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