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About Overhead Cranes
Overhead cranes are a standard fixture in many industrial,
manufacturing and assembly environments. The products made by overhead
crane manufacturers consist of a variety of components, which include
hoists, hooks and ropes. They are devices that raise and lower a desired
load and move it along a horizontal plane. This plane of movement is
determined by the type of overhead cranes used. The end of the load-bearing
arm is attached to wall columns, referred to as “overhung,” or
to the underside of the ceiling, also called “underhung,” Most
overhead crane systems are controlled via an operator remotely or via
a fixed housing control. Many of the more complex systems are fully automated,
acting as part of a larger assembly system.
Gantry, semi-gantry, cantilever gantry, storage bridge and wall cranes
are among the types of the products made by overhead crane manufacturers.
Gantry cranes are very similar to overhead cranes with the exception
of the bridge for the trolleys. Two or more legs support it as the crane
runs on fixed rails or another runway. One end of the bridge of a semi-gantry
crane is supported by one or more legs, with the other end attached to
a truck running on an elevated rail or runway. Cantilever gantry cranes
are either gantry or semi-gantry cranes on which the bridge girders or
trusses extend beyond the crane runway on one or both sides. Storage
bridge cranes are a type of gantry crane in which the bridge girders
or trusses are rigidly or non-rigidly supported on one or more legs and
may have one or more fixed or hinged cantilever ends. These long-span
overhead cranes are typically used for bulk storage applications. Wall
cranes are a traveling type of crane which has a jib, with or without
a trolley. These overhead cranes are supported from a side wall or lined
columns of a building to which the runway is attached.
Overhead crane manufacturers supply machinery to many different industries.
The automotive industry utilizes overhead cranes extensively in their
production facilities. Overhead cranes are also commonly used in the
construction of very tall structures. Conventional material handling
methods cannot be used for the oversized loads that must be shifted in
those industries. Moving heavy loads, like engines, requires the use
of heavy-duty overhead cranes. Relocating cargo containers and other
heavy non-assembly materials, such as blocks of concrete, is another
common use for overhead cranes. Other machinery, like hydraulic
lifts,
is also used for the raising and lowering of loads, sometimes in tandem
with overhead cranes.
Frequent inspections must be performed on overhead cranes for safety
purposes. Every day the operating mechanisms should be checked for maladjustment,
the pneumatic and hydraulic parts for leakage, the hooks for deformation
or cracks and the hoist chains and end connections for wear, twist or
distortion. The running rope and end connections should be checked on
a monthly basis for wear, broken strands, etc. Periodically, the overhead
cranes should be checked for deformed, cracked or corroded components,
loose bolts or rivets, cracked or worn sheaves and drums, other worn,
cracked or distorted parts (e.g. bearings, gears and rollers) and excessive
wear on brake system parts, chain drive sprockets and chains. Other components
to be inspected include electric or fossil-fuel motors, indicators and
electrical components, such as pushbuttons, limit switches or contactors
that may be corroded. OSHA has published a set of guidelines for the
safe operation of overhead cranes.
Featured
Articles
http://www.simlog.com/pdf/executive-view-CraneWorks-March-April-2005.pdf
http://www.bgcrane.com.au/bg_tech.asp
Types of Overhead Cranes
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fall between completely manual and completely robotic systems and are
used in applications in which robotic systems are much too expensive
and complex to operate. Automated cranes are equipped with encoder-based
fixed belt position and drive assemblies, and operate through a preset
cycle or cycles.
- ,
the most common type of overhead crane, consist of girders, trucks,
end ties, a walkway and a drive mechanism, which carries the trolley
and travels in a direction parallel to the runway.
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are a type of overhead crane in which the bridge for carrying the trolley
or trolleys is rigidly supported by two or more legs running on fixed
rails or a runway.
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is a generic term for a crane that is capable of lowering and lifting
a load. Most cranes have hoists.
- are
designed with the bridge girder, commonly called the "boom,"
fixed at one end, allowing the opposite end to cantilever. The fixed
end generally is hinged to allow rotation, and the jib can be telescopic
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have crane bridges to carry a heavy-lift hook trolley that is sometimes
equipped with an auxiliary host. Powerhouse cranes are able to be accurately,
reliably and safely operated due to their nearly infinitely variable
speed controls.
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consist of a base bolted into a large concrete pad, and a mast (or tower)
that gives the tower crane its height. The mast is connected to the
base and the gear and motor—called a slewing unit—that allows
the crane to rotate. Tower cranes are used in construction of tall structures.
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