Excavator with a Bucket of Boulders

About this drawing

An excavator scooping rocks shows how easily this machine changes tools to fit the job. There is no single bucket: narrow ones dig trenches, wide toothless ones clean ditches, and heavy-duty rock buckets like this one move stone.

A rock bucket has thicker walls and extra-hard teeth along the edge. Those teeth focus all the force on a few points, so the excavator can wedge between stones and pry them up. Teeth wear down with use, but they pop off and get replaced without swapping the whole bucket.

Many excavators carry a quick coupler between the arm and the tool. With it, the operator can drop the bucket and lock on another attachment in minutes: a hammer to break rock, a thumb to grab boulders or an auger to drill holes in the ground.

Working among big rocks calls for caution. The ground is uneven and stones can roll, so the operator moves slowly, keeps the bucket low while traveling and makes sure nobody is inside the swing radius of the cab. Before digging, crews also call to have buried pipes and cables marked, so the bucket never hits a hidden line.

• excavator
• rocks
• boulders
• construction
• machines