Excavators: Also Known as Diggers and Backhoes
An excavator uses hydraulics or a wire rope pulley system to dig holes or trenches and is, therefore, often called a digger. Excavators are also called bobcats and backhoes. An excavator has a long boom arm and a cab that is mounted on a pivot. The boom is connected at an elbow to a stick that holds the bucket.
The “bucket” attachment can be replaced with a different attachment depending on the requirements of the job site. The cab can pivot in a full circle. Because 360 degree rotation is available, another name for an excavator is a 360 degree digger.
The entire vehicle can either be on wheels or on tracks and is commonly used with loaders and bulldozers. Tracked excavators are sometimes known as trackhoes.
In addition to their use on construction sites, an excavator can also be used for heavy lifting in other industries, such as mining. An excavator can also be used for the following: material handling, demolition, landscaping, and river dredging.
Excavators are found in many different sizes depending on the job that is required. Small excavators are called mini or compact excavators. Often compact excavators come with a bulldozer blade on the front. The smallest compact models can fit through a doorway. The largest excavators can weigh over 180,000 lbs.
There are two types of compact excavators: tail swing and zero-tail swing. Conventional compact excavators were all tail swing units that had a rear counterweight to stabilize the vehicle while digging. The rear counterweight extends beyond the tracks when the cab rotates and sometimes makes maneuvering difficult for the operator. Zero-tail swing units came into production in the 1990s. As the name suggests, the counterweight does not move outside of the width of the tracks during rotation. Zero-tail swing units are easier for the operator to maneuver.
Excavators are usually specified by there dig depth, arm force, dump height, maximum height, and power rating.
Originally, excavators came with buckets at the end of the arms. However, today, many different attachments, such as breakers, grapples, or augers, are available. There are also different types of buckets: heavy duty, general purpose, pavement removal, tilt buckets, and sorting buckets. Tilt buckets allow the operator to control the side-to-side angle of the bucket. This type of attachment is used when grading or digging slopes. Sorting buckets allow the operator to separate large rocks from smaller material easily. Often the attachments are fitted with quick-attach mounting systems so that the ends can easily be switched at a job site.
Every major industrial machinery company has excavator models. The major suppliers include Catpillar, Bobcat, Hitachi, Ammann-Yanmar, Volvo, Hyundai, Case CE, Manitowoc, Mustang, JCB, Hydrema, Daewoo, Leibherr, and Komatsu.