An alligator shear, historically known as a lever shear,[1] is a metal-cutting shear with a hinged jaw, powered by a flywheel or hydraulic cylinder. Alligator shears are generally set up as stand-alone shears, however there are types for excavators. The jaw size can range from 4 to 36 in (100 to 910 mm) long. They are generally used to cut steel members, such as rebar, pipe, angle iron or I-beams

http://en.wikipedia.org/wiki/Alligator_shear