An alligator shear, historically known as a lever shear and sometimes as a crocodile shear, is a metal-cutting

shear Shear may refer to: Textile production *Animal shearing, the collection of wool from various species **Sheep shearing *The removal of nap during wool cloth production Science and technology Engineering *Shear strength (soil), the shear strength ...

with a hinged jaw, powered by a

flywheel A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, as ...

hydraulic cylinder A hydraulic cylinder (also called a linear hydraulic motor) is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment ( engineering vehicles ...

. Alligator shears are generally set up as stand-alone shears; however, there are types for excavators. The jaw size can range from long. They are generally used to cut ferrous members, such as rebar,

pipe Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circular ...

, angle iron, or I-beams...

Operation

Older alligator shears were powered by a

. These shears ran continuously, which posed a safety hazard. Now alligator shears are hydraulically actuated. When actuated, the piston arm extends and slowly closes the upper jaw of the alligator shear, which passes alongside the bed or lower jaw of the shear to perform the cut.

Uses

Alligator shears are used for cutting long metal stock or scrap, generally where accuracy is not an important consideration, and the size or shape of the material makes other cutting or shearing options (such as a

cutting torch Principle of burn cutting Oxy-fuel welding (commonly called oxyacetylene welding, oxy welding, or gas welding in the United States) and oxy-fuel cutting are processes that use fuel gases (or liquid fuels such as gasoline or petrol, diesel, ...

) impractical. Alligator shears are often used in conjunction with large metal shredders in the metal recycling industry, to 'clean' or prepare scrap for shredding by removing unwanted fittings and other parts the shredder will not accept.

Safety

The safety requirements for other powered

metalworking Metalworking is the process of shaping and reshaping metals to create useful objects, parts, assemblies, and large scale structures. As a term it covers a wide and diverse range of processes, skills, and tools for producing objects on every scal ...

shears are contained in

ANSI The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organi ...

B11.4, but alligator shears are specifically exempted from that standard. Federal

OSHA OSHA or Osha may refer to: Work * Occupational Safety and Health Administration, a federal agency of the United States that regulates workplace safety and health * Occupational Safety and Health Act (United States) of 1970, a federal law in the Un ...

and various state OSHA programs have requirements for guarding alligator shears, and newly manufactured alligator shears are provided with guards that adjust to the size of the stock or scrap being cut. The purpose of this guard, however, is to prevent pieces of metal from being ejected during cutting. Such a guard also prevents inadvertent exposure of the operator's hands, but does not conform to more stringent 'point of operation' guarding requirements. In an interpretive letter dated June 24, 1981, Federal

discussed the guarding dilemma presented by the alligator shear.

In instances where the shear is exclusively used for routine cuts on standardized stock, safeguarding of the point of operation is definable. In other instances, the operator is safeguarded from exposure to the point of operation by the physical size and configuration of the material being cut.

These practical considerations for guarding are not exclusive to alligator shears. A much more common type of equipment, the

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, also requires point of operation guarding when used with standardized stock, but not with large-dimension stock.

References

{{Reflist Metalworking cutting tools