A crawler excavator is a piece of heavy machinery designed to move large quantities of materials using a bucket mounted to an articulated boom arm. This machine is known as a crawler excavator because it is mounted on a set of tracks that "crawl" forward or backward rather than roll as tires would. These machines are commonly used at construction sites or for any heavy digging applications, though the bucket can be switched out with other attachments, making the machine useful for other applications.
The main body of the crawler excavator generally consists of two parts: the base, to which the tracks are mounted, and the house, in which the engine is mounted and the operator sits during use of the machine. The base will feature guide wheels over which the tracks will be run; two tracks will be mounted, one on either side of the machine, and parallel to each other. These tracks are used for propelling the unit forward and backward, and for providing stability on loose or muddy soil.
The house of the crawler excavator will contain the operator's cabin as well as the engine compartment. It is likely that the crawler excavator will feature a very large diesel engine for power and torque, so much of the house will be dedicated to the engine. The operator's cabin can be quite small, and it is usually enclosed to protect the operator from debris or the weather outside. Some of these cabins are heated and air conditioned as well for comfort. The controls for the tracks, the boom, and for the house itself are located inside the cabin. The house can usually rotate 360 degrees to allow for greater access of materials around the machine.
From the front of the house of the crawler excavator extends an articulated boom arm that is hydraulically controlled. A bucket is mounted to the end of this arm; the bucket is responsible for scooping and transporting materials, and the capacity of this bucket can vary depending on the size of the machine and the intended use of the crawler excavator. The machine itself will be rated for a certain capacity, and exceeding this capacity can cause the machine to become unstable and tip over. Larger machines will have a larger capacity, while smaller units are likely to only be sufficient for moving small amounts of material.