An alligator shear, historically known as a lever shear and sometimes as a crocodile shear, 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
excavator
Excavators are heavy construction equipment consisting of a boom, dipper (or stick), bucket and cab on a rotating platform known as the "house". The house sits atop an undercarriage with tracks or wheels. They are a natural progression fro ...
s. The jaw size can range from long. They are generally used to cut ferrous members, such as
rebar
Rebar (short for reinforcing bar), known when massed as reinforcing steel or reinforcement steel, is a steel bar used as a Tension (physics), tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concr ...
,
pipe,
angle iron
Structural steel is a category of steel used for making construction materials in a variety of shapes. Many structural steel shapes take the form of an elongated beam having a profile of a specific cross section. Structural steel shapes, sizes, ...
, or I-beams.
[.][.]
Operation
Older alligator shears were powered by a
flywheel. 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
Scrap consists of Recycling, recyclable materials, usually metals, left over from product manufacturing and consumption, such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap Waste valorization, has monetary ...
, 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) 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 shears are contained in
ANSI B11.4, but alligator shears are specifically exempted from that standard. Federal
OSHA 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 __NOTOC__
An interpretive discussion is a discussion in which participants explore and/or resolve interpretations often pertaining to texts of any medium containing significant ambiguity in meaning.
Education
Interpretive discussions are an ef ...
dated June 24, 1981, Federal
OSHA 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
press brake, also requires point of operation guarding when used with standardized stock, but not with large-dimension stock.
References
{{Reflist
Metalworking cutting tools