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What Is an Excavator Boom?

Dan Cavallari
Dan Cavallari

An excavator boom is a component used to operate an excavator, a piece of heavy machinery used for digging holes or otherwise moving large amounts of material. The excavator usually consists of a base with tracks or treads attached to rotating wheels, as well as a unit known as the house that rotates 360 degrees so the operator can access material on all sides of the machine without repositioning the entire unit. The excavator boom extends off the front of the house, and it usually consists of two pieces that articulate for better reach.

A bucket is mounted to the end of the excavator boom. This bucket is responsible for doing the digging as well as for containing the materials to be moved. All components of the excavator boom as well as the bucket itself are controlled by hydraulics; an outer stanchion filled with fluid — usually some sort of oil — can be pressurized, thereby causing an internal piston to push forward. When the pressure is released, the piston will retract. In this way, the two parts of the excavator boom as well as the bucket can be controlled from the operator's cabin of the machine.

An excavator's boom is the long, arm-like part that is used to lift and move a bucket that carries earth.
An excavator's boom is the long, arm-like part that is used to lift and move a bucket that carries earth.

Steel is usually used to construct the very large excavator boom arms. The two sections of the arm are hinged, and articulation is possible thanks to bearings or bushings at the connection points between the two boom arm sections. The hydraulics are mounted at various points along the length of the arms; they are strategically positioned to allow for the most efficient movements that will extend the arm as far as possible. other hydraulics are mounted near the bucket to extend or retract that attachment. These too will be mounted to allow for the most extension and retraction possible.

Other attachments can be affixed to the excavator boom. A quick-coupling design allows the user to switch out the bucket for another attachment to suit a particular job, thus adding to the versatility of the machine. Other attachments may include a jackhammer attachment, compaction wheels, cutting wheels, grappling arms, and so on. Grappling arms are especially useful for picking up or otherwise manipulating logs and trees. A jackhammer attachment is useful for breaking up concrete or asphalt quickly and effectively. Excavator rakes are available, as are amphibious attachments for dragging waters. Other specialty attachments for highly specialized applications can be made custom or may be made through limited production.

Discussion Comments


I have heard of excavator booms being used to dredge a bay or river. My grandfather told me that he used to be involved in the process.

He said that when huge amounts of sediment had piled up, this would create problems for people in ships and boats. They wouldn't be aware of the newly formed shallow spots, and they could get stuck or wreck their vessel on them.

So, my grandfather was one of the people who got to operate the mechanical dredge. A bucket attached to an excavator boom would scoop up the sediment and toss it into a barge. This probably saved a lot of lives, or at least a lot of money in boat repairs!


@Oceana – Excavators really can move a ton of earth in a short amount of time. I saw the workers landscaping an empty lot across from my house, and in just a couple of hours, they had cleared the entire area of grass.

The grass got replaced by fresh dirt, and the boom arms were hard at work, pushing around the excavator buckets that were stacking the new earth into place. The workers were trying to make a gently sloping hill out of a steep cliff, and they were doing a wonderful job of it.

When they had finished, the lot seemed like it had been pushed further back. The cliff had been graded to a slightly rolling hill, and it looked much more attractive.


My husband's demolition company recently had to buy an excavator boom extension. They were used to doing small jobs, like old houses and stores, but they won a bid to tear down a five-story building, and they simply did not have a boom arm long enough for the job.

I was astonished at the length of the one that they purchased. Normally, they used two arm segments. This one had three segments.

I saw it in action, and it made me a little dizzy. I have a fear of heights anyway, and seeing this boom arm reach up so high made me feel a little woozy.


My dad has a backhoe, and it also has an excavator attached. He always told me that the part of the arm nearest to the backhoe was called the boom, and the forearm was called the dipper.

So, the bucket with metal teeth hangs from the dipper. He operates it from his seat inside the backhoe, making it swing and dip at his command.

I have seen him use it to bury a bull. He just drove right up to it, lowered the bucket to the ground right beside the bull, and began shoveling large amounts of earth out to make a grave. I was amazed at how quickly a grave large enough for a bull could be dug by this machine.

When he was through digging, he made the bucket curl under the bull and pull him into the grave. It was like watching a giant hand do all this work with ease.

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    • An excavator's boom is the long, arm-like part that is used to lift and move a bucket that carries earth.
      By: Kadmy
      An excavator's boom is the long, arm-like part that is used to lift and move a bucket that carries earth.