Crane (machine)

A crane (plural: cranes or cranes - cranes is usually regarded as cranes colloquially as specialized claims; derived from the ancient Greek ὁ γέρανος the crane. ) Is operated manually or by motor means for vertical and horizontal loading of loads. It is generally used for loading and unloading ships ( cargo and container), rail and trucks as well as in assembly, manufacturing and warehouses as well as in building construction.

In the version for the handling of bulk materials it is usually referred to as an excavator.

The difference to a simple hoist that can be part of the crane is that the crane is floor-free and more than two directions of movement (up / down - left / right is equivalent to two coordinate directions ) can perform (three-dimensional workspace ) - that is, the depose load at another point, when he recorded it.

The main application is the loading and unloading, also called cargo handling, as well as the abandoned Tung of goods to a certain point (short distances). The latter application is very important, especially on construction sites.

• 9.1 Monographs
• 9.2 journal articles
• 9.3 history

Crane types

There are different types and designs depending on the application.

• Bridge crane, incorrectly referred to as overhead crane, overhead crane or overhead crane track.
• Gantry crane built like a gate, built rail track / track race on earth (hall) or Trackless gantry cranes on wheels / tracks work. gantry crane
• Semi-gantry crane
• Loading bridge crane bridge, for example, the port
• Portalwippdrehkran
• Full Portal Wippdrehkran

• Rail-mounted crane, rail crane, rail crane.
• Overhead crane

• Truck crane, mobile crane
• Terrain slow runner ( Rough terrain cranes )
• All- terrain cranes
• Crawler Crane
• Travel lift ( to lift ships out of the water and transported to the shipyard )
• ( To derive a large scale 1 or 2 channel rings, each for 4 vielrädrige drives the load into the ground ) Ring crane

• Ship crane, deck crane
• Stationary container crane when loading or Entladebrücke for container ships
• Special cranes ( loading bridges ) for special cargoes such as grain and tropical fruits ( bananas)

• Large crane

Distinction according to the mast construction

• Telescopic crane
• Lattice boom crane

Portable jib cranes are called mobile cranes.

Hans Liebherr constructed in 1949 the first mobile tower crane in the world, the TK 8, with initially moderate success.

Miscellaneous

Helicopter, cable cars, balloons and kites ( ferries ) can possibly take over the function of a crane. Their use is restricted because of the high operating costs, normally on an impassable areas or for work on very tall buildings. Specially designed for the use of a crane helicopter types are: K- Max, Sikorsky S-64 Skycrane, Mil Mi- 10th A trial balloon was 2001/2001 Cargo Lifter CL75 AirCrane 75 t payload.

Functionally similar to the following tools: fishing rod, boat hooks, gripping aid, fire hook, hook rod for clothes on hangers to overhead bars to manipulate or tilt small boxes from high shelves down.

30 cranes on 21 acres moving at dusk of February 15, 2014 as a choreographed ballet with light effects for 15-minute symphony Kranensee composed by Florian Reithner on the construction site of heat in the northeast of Vienna Aspern Urban Lakeside. Thus, the construction companies celebrated the first roof peers and 14000 came to watch. Crane ballet was presented in 1996 in the transformation of Potsdamer Platz Berlin and 2010 as a requiem of the cranes in the HafenCity Hamburg.

Etymology

The lifting device of a vertical column and a rotatable, mostly obliquely upward boom reminiscent of the long neck and beak of a crane standing. Therefore, already named by the Greeks after the construction of the bird. In the Middle Ages the short form was then removed from the crane original crane. In the Middle Ages, as well spellings with "h" or ending in " s " were used, such as old-age Krahnen.

History of cranes

Ancient Greek cranes

The crane for lifting heavy loads was invented in the late 6th century BC by the ancient Greeks. Characteristic notches for the use of lifting tongs and Lewis iron are detected from approximately 515 BC to stone blocks of Greek temples. Since these furrows are located either above the center of gravity of the block, or in pairs equidistant from a point above the center of gravity, they are regarded by archaeologists as sufficient proof of the existence of cranes.

The introduction of lifting machines that worked with winch and pulley, led to largely dispense with the ramp as a home remedy for vertical transport. In the following two centuries can be attributed to Greek construction sites, a strong trend to lighter loads determined. In contrast to the archaic period ( 700-500 BC), in which the size of the processed stone blocks always continued to increase, have classical Greek temples such as the Parthenon consistently blocks that weigh less than 15 to 20 tons. In addition, it moved from the former practice to build large monolithic columns, and proceeded to assemble columns of several drums.

Although the historical background of the introduction of the crane remain unclear, it is considered that the unstable social and political situation in Greece favored the employment of small, professional construction crews. This allowed the use of cranes for the polis appear more attractive than the ramp technique that required the mass deployment of workers and in the autocratic societies of Egypt or Assyria was common.

The first unambiguous written evidence for a multi -roller train is found in the Mechanical Problems ( Mechanika 18, 853a32 - 853b13 ) attributed to Aristotle ( 384-322 BC ), but were probably written somewhat later. At about the same time reached the stone blocks of Greek temples again the size of their archaic predecessors, indicating that the multi-roller - train must have made ​​its entrance on Greek sites at this time.

Ancient Roman Cranes

A particularly important role was played by cranes in construction of the Romans, where there was a building boom and its buildings reached enormous proportions. The Romans took the crane by the Greeks and developed it further. Thanks to the relatively detailed treatises of the Roman engineers Vitruvius ( De Architectura 10, 2, 1-10) and Heron of Alexandria ( Mechanica 3, 2-5 ), we are relatively well informed about the Roman lifting equipment. Pictures of Roman Tretradkrane can be found on two ancient reliefs, of which the grave stone of Haterii from the late 1st century AD is particularly detailed.

The simplest Roman crane was a three-roller train, which was accordingly named Trispastos and consisted of lifting tree, reel, rope, and a block with three rollers, which corresponds to a ratio of 3 to 1. According to calculations could with the Trispastos a single worker on the reel - assuming that 50 kg represent the maximum power input, a man can exert over a longer period - a weight of 150 kg lift ( 3 rolls of 50 kg = 150 kg ). Heavy crane types had more complex tackles with five rollers ( Pentaspastos ) or in the case of the largest crane even three by five pulleys ( Polyspastos ) and had, depending on the maximum load two, three or four lifting masts. The Polyspastos could reel in operation with four men already lift 3000 kg (3 ropes x 5 rolls x 4 men x 50 kg = 3000 kg ). If the reel replaced by a treadmill, the maximum weight even doubled to 6000 kg at half the crew, since the treadmill due to its larger diameter has a much greater ratio. This means that the maximum lifting force of the Roman Polyspastos 3000 kg per person was sixty times greater than in the construction of the pyramids, where it took about 50 workers, a 2.5 ton stone block up the ramp move (50 kg per person).

Archaeological evidence suggests that the Romans possessed the technical ability nor to carry much larger loads vertically, as in many Roman buildings can be found in a higher position much heavier stone blocks than they could cope with the Polyspastos. For example, weigh the architraves temple of Jupiter in Baalbek, which is about 19 ​​m are located above the ground, up to 60 t and the blocks of Eckgesims even over 100 tons, while the 53.3 -tonne Kapitellblock the Trajan's Column in Rome, was installed at a height of about 34 m.

It is assumed that Roman engineers were able to cope with these exceptional loads by two measures: first, a wooden lifting tower was, as suggested by Heron, built with all four sides had the shape of a square with sides parallel, a siege tower not unlike, but with the column in the middle of the structure ( Mechanica 3, 5). Second, a plurality of anchor winches at the feet of the tower was placed, which were manned by crews. Windlasses enjoyed despite their smaller lever ratio in preference to treadwheels because they are prepared in larger quantities and more workers (and beyond draft animals ) could be served. The use of windlasses is of Ammianus Marcellinus (17, 4, 15 ) described the raising of the Lateran Obelisk in the Circus Maximus (ca. 357 AD). The maximum lifting capacity ancient anchor winches can be determined by the number of Lewis iron holes that were drilled into the monolith. In the case of the architrave of Baalbek, which weigh between 55 and 60 tonnes, many windlasses with an individual maximum load of 7.5 t let eight holes on the use similarly close (60 t / 8 holes = 7.5 t). Such large loads to lift in a concerted action required of the working groups at the windlasses a high degree of concentration and coordination.

Medieval cranes

After the Tretradkran had fallen with the fall of the Western Roman Empire in Western Europe out of use, the lifting technique found in the High Middle Ages in their large-scale re-entry. The earliest mention of a Tretrads ( magna rota ) appears in French sources around 1225, followed by an illustration in a manuscript of 1240, which is also likely to be of French origin. In shipping, the earliest uses of harbor cranes for Utrecht in 1244, Antwerp in 1263, Brugge in 1288 and Hamburg in 1291 documented, while in England the treadmill for the first time in 1331 is tangible.

Generally, vertical transport could be done safer and cheaper by cranes than with conventional methods. Typical areas of application were harbors, mines and construction sites in particular where the Tretradkran played a key role in the establishment of the towering Gothic cathedrals. Nevertheless, it can be seen based on contemporary sources and illustrations that newly introduced machines like treadmills and wheelbarrows could not completely replace more labor-intensive methods like ladders and carrying stretchers. Rather, old and new machines were used in the medieval construction and port operations side by side.

Apart from treadwheels show medieval representations cranes manually winches with star-shaped spokes, cranks and since the 15th century, driven by winds that are shaped like a steering wheel. Flywheels, balance the irregularities in the drive and help overcome dead spots in the lifting process are proven known since 1123.

Origins

The exact process that led to the reuse of the Tretradkrans is not known, but his return to medieval construction sites must be no doubt seen in close connection with the simultaneous rise of Gothic. The Tretradkran could be a technical development of the winds, of the derived its structure and mechanics. Alternatively, the medieval treadmill could be a conscious reinvention of the Roman crane, as it is described in Vitruvius 's De architectura, which belonged to the inventory of many monastic libraries. Likewise, its reintroduction by observing the labor-saving qualities of water wheels could have been inspired by which early Tretradkonstruktionen had many similarities.

Structure and placement

The medieval treadmill consisted of a large wooden wheel, which revolved around an axis and a tread had, which was wide enough for two workers walking side by side. While early wheels of the compass - type ' the spokes inserted directly into the axle, had more advanced models, clamp - type' arms that were attached laterally to the axis. This arrangement allowed the use of a thinner drive shaft, which the mechanical lever enlarged.

Unlike often assumed medieval cranes were erected either on the then usual light stands still on the thin walls of the Gothic cathedrals, who did not have the carrying capacity to accommodate the added weight of the tractor and load. Rather, cranes were placed in the first phase of construction on the ground, often within the building. Once a floor was built and massive tie beam, the side walls joined to each other, the crane was dismantled and reassembled on the roof beams again, where he was moved during the construction of the vault from field to field. In this way, " grew up " and " wandering " of the crane to the building, so that nowadays all existing medieval construction cranes in England are in church towers above the vaulting and below the roof, where they remained after completion of works to uplift materials for repairs.

Less frequently, medieval representations of cranes on the outer sides of the walls, where the frame of the machine was attached to the protruding beams.

Operating mechanism and

In contrast to modern cranes, medieval cranes moving - just like their ancient predecessors - suitable loads hardly in the horizontal direction, but were primarily only for vertical lifting operations. According to the different lifting work was organized at the workplace. Thus, we believe that in building construction crane the stone blocks either directly heaved from the ground to her place, or from one point, the faced the wall center, so that the two work crews that worked at both ends of the wall, supplied with building materials could.

In addition, led the crane master who usually conducted by the workers in the treadmill outside of the crane, the load on a small rope with which he was able to swing the load sideways. Slewing cranes which allowed a rotation of the load and were thus particularly suitable for unloading on the quay, can be detected as early as 1340. While ashlar stones with slings, Lewis iron or lifting tongs (, devil's claw ') were lifted, other objects with containers such as baskets, wooden boxes, pallets or drums were transported.

It is worth mentioning that the medieval crane rarely ratchets or brakes had to prevent the charge ran backwards. This is explained by the high friction forces, which normally prevented the wheel is accelerated uncontrollably.

Harbor cranes

Stationary harbor cranes - unknown according to present knowledge in the ancient world - be regarded as a new development of the Middle Ages. The typical harbor crane was a rotatable design, equipped with two treadwheels. These cranes were built for loading and unloading of cargo on the quay, where they replaced or complemented older lifting methods such as winches, seesaws and yards.

Two types of harbor cranes with different geographical focal points can be identified: For a buck cranes whose entire structure revolved around a central vertical axis and which were commonly found in Flemish and Dutch coastal towns. On the other tower cranes, which winch and wheels were in a strong tower, and only the boom and the roof structure with the load turned. This type was used in the German sea and inland harbors. Interestingly, Kaikrane were not adopted in the Mediterranean region and the highly developed Italian port cities, where the authorities on the Middle Ages also made ​​use of the more labor-intensive method of unloading ramps.

Unlike construction cranes where the work speed was determined by the relatively slow pace of work of the masons, harbor cranes usually had a double treadmill to speed up the loading process. The two treadmills, the diameter is estimated to be 4 m or more were attached to both sides of the crane axis, and turned together. Nowadays exist after an investigation fifteen treadwheel port cranes from pre-industrial era in Europe. Beside these stationary cranes came on in the 14th century, floating cranes which could be used in the whole port basin flexible.

Security

Before the first use of a crane ( hoist ) is 905 ( BG ) principles by an approved by the professional association of experts necessary in Germany, an acceptance test according to BGG. This acceptance test ranges from the sighting of the present for a crane documents to inspection of all safety-related features, security clearances and adjacent areas. For a more detailed explanation will be made ​​in this connection, inter alia, to the accident prevention regulation BGV D 6 cranes. The yearly examination is then given by an expert ( BGV D 6 § 26) to perform.

The operators of cranes is recommended its crane operators to train in accordance with the applicable principles of professional associations (BGG 921 ).

Museum cranes

• Roman crane with wheel in Aalen
• Crane with wheel, outdoor grounds of the Abbey of Hambye (Normandy).
• Crane and Construction museum with a large collection of the most essential construction crane constructions

Known cranes

• List of historical harbor cranes from the Middle Ages, Renaissance and Baroque
• Big Blue (crane)
• Harland and Wolff Samson and Goliath in Belfast
• Kockumskran in Malmö ( dismantled )
• Thialf