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Gantry cranes, bridge cranes, and overhead cranes, are all types of cranes which lift objects by a hoist which is fitted in a hoist trolley and can move horizontally on a rail or pair of rails fitted under a beam.
An overhead travelling crane, also known as an overhead crane or as a suspended crane, has the ends of the supporting beam, the gantry, resting on wheels running on rails at high level, usually on the parallel side walls of a factory or similar large industrial building, so that the whole crane can move the length of the building, while the hoist can be moved to and from across the width of the building. A gantry crane or portal crane has a similar mechanism supported by uprights, usually with wheels at the foot of the uprights allowing the whole crane to traverse. Some portal cranes may have only a fixed gantry, particularly when they are lifting loads such as railway cargoes that are already easily moved beneath them.
Overhead crane and gantry crane are particularly suited to lifting very heavy objects and huge gantry cranes have been used for shipbuilding where the crane straddles the ship allowing massive objects like ships' engines to be lifted and moved over the ship. Two famous gantry cranes built in 1974 and 1969 respectively, are Samson and Goliath, which reside in the largest dry dock in the world in Belfast, Northern Ireland. Each crane has a span of 140 metres and can lift loads of up to 840 tonnes to a height of 70 metres, making a combined lifting capacity of over 1,600 tonnes, one of the largest in the world.
However; gantry cranes are also available running on rubber tyres so that tracks are not needed, and small gantry cranes can be used in workshops, for example for lifting automobile engines out of vehicles.
A ship-to-shore rail mounted gantry crane is a specialised version of the gantry crane in which the horizontal gantry rails and their supporting beam are cantilevered out from between frame uprights spaced to suit the length of a standard freight container, so that the beam supporting the rails projects over a quayside and over the width of an adjacent ship allowing the hoist to lift containers from the quay and move out along the rails to place the containers on the ship. The uprights have wheels which run in tracks allowing the crane to move along the quay to position the containers at any point on the length of the ship. The first versions of these cranes were designed and manufactured by Paceco Corporation They were called Portainers and became so popular that the term Portainer is commonly used as a generic term to refer to all ship-to-shore rail mounted gantry cranes.
Workstation gantry cranes
Workstation gantry cranes are used to lift and transport smaller items around a working area in a factory or machine shop. Some workstation gantry cranes are equipped with an enclosed track, while others use an I-beam, or other extruded shapes, for the running surface. Most workstation gantry cranes are intended to be stationary when loaded, and mobile when unloaded. Workstation Gantry Cranes can be outfitted with either a Wire Rope hoist as shown in the above hoist (device) picture or a lower capacity Chain Hoist.
Rail mounted gantry (RMG) cranes
Rail mounted gantry cranes (RMG) are commonly found in factory applications such as steel yards, paper mills or locomotive repair shops. The EOT gantry crane functions similarly to an overhead bridge crane, but has rails installed on the ground and gantry-style legs to support the crane. Capacities range from 2 to 200 tons, and sometimes even greater capacities. Most are electrically powered and painted safety yellow.
When bridge cranes and gantry cranes became more popular in factories in the late 1800s a steam engine was sometimes used as a way to power these devices. The lifting and moving would be transferred from a fixed line shaft. The picture on the right shows an example of system powered by a line shaft and steam engine. The overhead crane is from 1875, and was one of the first systems to be powered in such a way.
EOT (Electric Overhead Traveling) Crane
This is most common type of overhead crane, found in most factories. As obvious from name, these cranes are electrically operated by a control pendant, radio/IR remote pendant or from an operator cabin attached with the crane itself.
Gantry cranes using built-up style hoists are frequently used in modern systems. These built up hoists are used for heavy-duty applications such as steel coil handling and for users desiring long life and better durability. Also used 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 which 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 (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 that also include gantry cranes. The members of this group are marketing representatives of the member companies.
- 1840: Mass production of overhead cranes starts in Germany.
- 1861: First steam powered overhead crane, installed by John Ramsbottom at the Crewe Railway workshops. 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: first Mass production Electric motor hoist start being produced in Germany.
Notable gantry cranes and dates
- 2008: The world's strongest gantry crane, Taisun, which can lift 20,000 metric tons, was installed in Yantai, China at the Yantai Raffles Shipyard.
- QIDONG, China, Oct. 23, 2012 Honghua Group Limited,China’s largest exporter of drilling rigs, announced that it will begin construction of the “Honghai Crane” at a ground-breaking ceremony today in Qidong City, Jiangsu Province, China. When completed, the “Honghai Crane” will boast the largest lifting capacity of any movable gantry crane in the world at 22,000 tons.
- Container terminal
- New York Central Railroad 69th Street Transfer Bridge
- List of historical harbour cranes
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