Overhead crane
Encyclopedia
Crane (machine)
A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of...
found in industrial environments. An overhead crane consists of parallel runways with a traveling bridge spanning the gap. A hoist
Hoist (device)
A hoist is a device used for lifting or lowering a load by means of a drum or lift-wheel around which rope or chain wraps. It may be manually operated, electrically or pneumatically driven and may use chain, fiber or wire rope as its lifting medium. The load is attached to the hoist by means of a...
, the lifting component of a crane, travels along the bridge.
Unlike mobile or construction cranes, overhead cranes are typically used for either manufacturing or maintenance applications, where efficiency or downtime are critical factors.
Applications
The most common overhead crane use is in the steel industry. At every step of the manufacturing process, until it leaves a factory as a finished product, steelSteel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
is handled by an overhead crane. Raw materials are poured into a furnace
Furnace
A furnace is a device used for heating. The name derives from Latin fornax, oven.In American English and Canadian English, the term furnace on its own is generally used to describe household heating systems based on a central furnace , and sometimes as a synonym for kiln, a device used in the...
by crane, hot steel is stored for cooling by an overhead crane, the finished coil
Coil
A coil is a series of loops. A coiled coil is a structure in which the coil itself is in turn also looping.-Electromagnetic coils:An electromagnetic coil is formed when a conductor is wound around a core or form to create an inductor or electromagnet...
s are lifted and loaded onto truck
Truck
A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...
s and train
Train
A train is a connected series of vehicles for rail transport that move along a track to transport cargo or passengers from one place to another place. The track usually consists of two rails, but might also be a monorail or maglev guideway.Propulsion for the train is provided by a separate...
s by overhead crane, and the fabricator
Fabrication (metal)
Fabrication as an industrial term refers to building metal structures by cutting, bending, and assembling. The cutting part of fabrication is via sawing, shearing, or chiseling ; torching with handheld torches ; and via CNC cutters...
or stamper uses an overhead crane to handle the steel in his factory. The automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
industry uses overhead cranes for handling of raw materials. Smaller workstation
Workstation
A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems...
cranes handle lighter loads in a work-area, such as CNC mill or saw.
Almost all paper mills use bridge cranes for regular maintenance requiring removal of heavy press rolls and other equipment. The bridge cranes are used in the initial construction of paper machines because they facilitate installation of the heavy cast iron paper drying drums and other massive equipment, some weighing as much as 70 tons.
In many instances the cost of a bridge crane can be largely offset with savings from not renting mobile cranes in the construction of a facility that uses a lot of heavy process equipment.
Configurations
While sharing major components, overhead cranes are manufactured in a number of configurations based on applications.Rotary overhead crane
This type of overhead crane has one end of the bridge mounted on a fixed pivot and the other end carried on an annular track; the bridge traverses the circular area beneath. This offers improvement over a jib crane by making possible a longer reach and eliminating lateral strains on the building walls.History
Demag Cranes & Components Corp. was one of the first companies in the world to mass-produce the first steam-powered crane. Since that time Alliance Machine, now defunct, holds an AISEAise
Aise ,an instrumental dance tune common throughout the eastern Mediterranean. Sections of its melody are found as part of “Selanik”, a tune from Macedonia; in apiece by the Ottoman Armenian composer Tatyos Efendi; and in the song, “Love’s Like a Pin,”from Asia Minor and Propontis...
citation for one of the earliest cranes in the USA market. This crane was in service until approximately 1980, and is now in a museum in Birmingham, Alabama
Birmingham, Alabama
Birmingham is the largest city in Alabama. The city is the county seat of Jefferson County. According to the 2010 United States Census, Birmingham had a population of 212,237. The Birmingham-Hoover Metropolitan Area, in estimate by the U.S...
. Over the years important innovations, such as the Weston load brake (which is now rare) and the wire rope hoist (which is still popular), have come and gone. The original hoist contained components mated together in what is now called the built-up style hoist. These built up hoists are used for heavy-duty applications such as steel coil handling and for users desiring long life and better durability. They also provide for easier maintenance. Now many hoists are package hoists, built as one unit in a single housing, generally designed for ten-year life, but the life calculation is based on an industry standard when calculating actual life. See the Hoists Manufacturers Institute site for true life calculation witch is based on load and hours used. In today's modern world for the North American market there are a few governing bodies for the industry. The Overhead Alliance is a group that represents Crane Manufacturers Association of America
Crane Manufacturers Association of America
The Crane Manufacturers Association of America is an independent trade association in the United States. It is affiliated with the United States Division of Material Handling Industry. The voluntary association of CMAA members has existed since 1955. Member companies represent industry leaders in...
(CMAA), Hoist Manufacturers Institute (HMI), and Monorail Manufacturers Association (MMA). These product counsels of the Material Handling Industry of America have joined forces to create promotional materials to raise the awareness of the benefits to overhead lifting. The members of this group are marketing representatives of the member companies.
Early manufacture
- 1830: First Crane company in Germany Ludwig Stuckenholz company now DemagDemagDemag or Demag Cranes AG is a German heavy equipment manufacturer now controlled by US based Terex. The roots of Demag date back prior to its formation, but became Märkische Maschinenbau-Anstalt, Ludwig A.-G in 1906 as the biggest crane building company in Germany employing 250-300 people...
Cranes & Components GmbH.
- 1840: Mass productionMass productionMass production is the production of large amounts of standardized products, including and especially on assembly lines...
of overhead cranes starts in Germany - 1861: First steam poweredSteam engineA steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...
overhead crane, installed by John RamsbottomJohn Ramsbottom (engineer)John Ramsbottom was an English mechanical engineer who created many inventions for railways, including the piston ring, the Ramsbottom safety valve, the displacement lubricator, and the water trough.- Biography :...
at the Crewe Railway workshopsCrewe WorksCrewe railway works is a British railway engineering facility built in 1840 by the Grand Junction Railway. It is located in the town of Crewe, in the county of Cheshire....
. Power was transmitted to the crane from a pulley driven by a stationary engine through an endless cotton rope. - 1887: Ludwig Stuckenholz company introduces electrical components to overhead cranes determining industry design.
- 1910: The first Mass productionMass productionMass production is the production of large amounts of standardized products, including and especially on assembly lines...
Electric motorElectric motorAn electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
hoist start being produced in Germany.