A crane is
a machine used for lifting and lowering a load,
and moving it horizontally. A crane's drives may
be manual, powered or a combination of both.
Cranes are typically used when there is
insufficient (or intermittent) flow volume such
that the use of a conveyor cannot be justified.
They provide more flexibility in movement than
conveyors, and less flexibility in movement than
industrial trucks. Loads handled by cranes are
more varied with respect to their shape and
weight than those handled by a conveyor. Most
cranes utilize hoists for vertical movement,
although manipulators can be used if precise
positioning of the load is required.
Many different types of cranes are used for
material handling applications. These include
overhead cranes as well as cherry picker type
boom lifts, mobile and self-propelled cranes,
straddle and counterbalanced (cantilevered)
cranes. Portable and mobile floor cranes can be
equipped with fixed or telescopic booms as well
as mast rotation when equipped with outriggers.
Lifting can be performed with the boom itself or
a winch operated cable lift.