A backhoe—also called rear actor or back actor—is a type of excavating equipment, or excavator, consisting of a digging bucket on the end of a two-part articulated arm. It is typically mounted on the back of a tractor or front loader, the latter forming a "backhoe loader". The section of the arm closest to the vehicle is known as the boom, while the section that carries the bucket is known as the dipper, both terms derived from steam shovels. The boom, which is the long piece of the backhoe arm attached to the tractor through a pivot called the king-post, is located closest to the cab. It allows the arm to pivot left and right, typically through a range of 180 to 200 degrees, and also enables lifting and lowering movements.