100-680: The London Docks were one of several sets of docks in the historic Port of London . They were constructed in Wapping , downstream from the City of London between 1799 and 1815, at a cost exceeding £5½ million. Traditionally ships had docked at wharves on the River Thames , but by the late 1700s more capacity was needed. They were the closest docks to the City of London until St Katharine Docks were built two decades later. The London Dock Company
200-478: A mechanical advantage of 3:1, it has been calculated that a single man working the winch could raise 150 kg (330 lb) (3 pulleys x 50 kg or 110 lb = 150), assuming that 50 kg (110 lb) represent the maximum effort a man can exert over a longer time period. Heavier crane types featured five pulleys ( pentaspastos ) or, in case of the largest one, a set of three by five pulleys ( Polyspastos ) and came with two, three or four masts, depending on
300-570: A central vertical axle, were commonly found at the Flemish and Dutch coastside, German sea and inland harbors typically featured tower cranes where the windlass and treadwheels were situated in a solid tower with only jib arm and roof rotating. Dockside cranes were not adopted in the Mediterranean region and the highly developed Italian ports where authorities continued to rely on the more labor-intensive method of unloading goods by ramps beyond
400-656: A concerted action required a great amount of coordination between the work groups applying the force to the capstans. During the High Middle Ages , the treadwheel crane was reintroduced on a large scale after the technology had fallen into disuse in western Europe with the demise of the Western Roman Empire . The earliest reference to a treadwheel ( magna rota ) reappears in archival literature in France about 1225, followed by an illuminated depiction in
500-526: A constant pressure, thus increasing the crane's load capacity considerably. One of his cranes, commissioned by the Italian Navy in 1883 and in use until the mid-1950s, is still standing in Venice , where it is now in a state of disrepair. There are three major considerations in the design of cranes. First, the crane must be able to lift the weight of the load; second, the crane must not topple; third,
600-471: A day's work; and a day's work could be 24 hours of continuous labouring. In addition, the work itself was incredibly dangerous. A docker would suffer a fatal injury from falling cargo almost every week during 1900, and non-fatal injuries were even more frequent. The London dockers handled exotic imports such as precious stones, African ivory, Indian spices, and Jamaican rum that they could never dream of purchasing themselves, and so robberies were very common on
700-588: A deep water channel, added the King George V Dock (1920) to the Royal group, and made continuous improvements to the other enclosed dock systems throughout the first two-thirds of the 20th century. This culminated in expansion of Tilbury in the late 1960s to become a major container port (the UK's largest in the early 1970s), together with a huge riverside grain terminal and mechanised facilities for timber handling. Under
800-407: A height of about 34 m (111.5 ft) (see construction of Trajan's Column ). It is assumed that Roman engineers lifted these extraordinary weights by two measures (see picture below for comparable Renaissance technique): First, as suggested by Heron, a lifting tower was set up, whose four masts were arranged in the shape of a quadrangle with parallel sides, not unlike a siege tower , but with
900-834: A line drawn from Foulness Point in Essex via Gunfleet Old Lighthouse to Warden Point in Kent ) with the North Sea and including any associated docks. Once the largest port in the world, it was the United Kingdom's largest port as of 2020. Usage is largely governed by the Port of London Authority ("PLA"), a public trust established in 1908; while mainly responsible for coordination and enforcement of activities it also has some minor operations of its own. The port can handle cruise liners, roll-on roll-off ferries and cargo of all types at
1000-529: A manuscript of probably also French origin dating to 1240. In navigation, the earliest uses of harbor cranes are documented for Utrecht in 1244, Antwerp in 1263, Bruges in 1288 and Hamburg in 1291, while in England the treadwheel is not recorded before 1331. Generally, vertical transport could be done more safely and inexpensively by cranes than by customary methods. Typical areas of application were harbors, mines, and, in particular, building sites where
1100-609: A much greater lifting capability than was previously possible, although manual cranes are still utilized where the provision of power would be uneconomic. There are many different types of cranes, each tailored to a specific use. Sizes range from the smallest jib cranes, used inside workshops, to the tallest tower cranes, used for constructing high buildings. Mini-cranes are also used for constructing high buildings, to facilitate constructions by reaching tight spaces. Large floating cranes are generally used to build oil rigs and salvage sunken ships. Some lifting machines do not strictly fit
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#17327733060211200-408: A point over the center of gravity, they are regarded by archaeologists as the positive evidence required for the existence of the crane. The introduction of the winch and pulley hoist soon led to a widespread replacement of ramps as the main means of vertical motion. For the next 200 years, Greek building sites witnessed a sharp reduction in the weights handled, as the new lifting technique made
1300-443: A vertical lift, and not used to move loads for a considerable distance horizontally as well. Accordingly, lifting work was organized at the workplace in a different way than today. In building construction, for example, it is assumed that the crane lifted the stone blocks either from the bottom directly into place, or from a place opposite the centre of the wall from where it could deliver the blocks for two teams working at each end of
1400-439: A winter day.. .. Three more power stations, at Belvedere (Oil-firing), and Northfleet and West Thurrock (coal-firing), are being built. This coal was handled directly by riverside coal handling facilities, rather than the docks. For example, Beckton Gas Works had two large piers which dealt with both its own requirements and with the transfer of coal to lighters for delivery to other gasworks. A considerable proportion of
1500-404: Is a machine used to move materials both vertically and horizontally, utilizing a system of a boom , hoist , wire ropes or chains , and sheaves for lifting and relocating heavy objects within the swing of its boom. The device uses one or more simple machines , such as the lever and pulley , to create mechanical advantage to do its work. Cranes are commonly employed in transportation for
1600-458: Is near the deck. Additionally, the DLF increases further when lifting objects that are underwater or going through the splash zone. The wind speeds tend to be higher than onshore as well. Though actual DLF values are determined through crane tests under representative operational conditions, design specifications can be used for guidance. The values vary according to the specification, which reflects
1700-418: Is noteworthy that medieval cranes rarely featured ratchets or brakes to forestall the load from running backward. This curious absence is explained by the high friction force exercised by medieval tread-wheels which normally prevented the wheel from accelerating beyond control. According to the "present state of knowledge" unknown in antiquity, stationary harbor cranes are considered a new development of
1800-464: Is open space. A small canal runs across the southern part of the Western Dock site from Hermitage Basin to Tobacco Dock. 51°30′21.6″N 0°3′37.2″W / 51.506000°N 0.060333°W / 51.506000; -0.060333 Port of London The Port of London is that part of the River Thames in England lying between Teddington Lock and the defined boundary (since 1968,
1900-405: Is usually part of the crane's type approval . In offshore lifting, where the crane and/or lifted object are on a floating vessel, the DLF is higher compared to onshore lifts because of the additional movement caused by wave action. This motion introduces additional acceleration forces and necessitates increased hoisting and lowering speeds to minimize the risk of repeated collisions when the load
2000-517: The British Trades Union movement, leading to the betterment of labourers across London. Alongside the docks many port industries developed, some of which (notably sugar refining , edible oil processing , vehicle manufacture and lead smelting ) survive today. Other industries have included iron working, casting of brass and bronze, shipbuilding , timber, grain, cement and paper milling, armament manufacture, etc. London dominated
2100-769: The City Canal , was subsequently cut across the Isle of Dogs. London's Docklands had their origin in the lack of capacity in the Pool of London which particularly affected the West India trade. In 1799, the West India Dock Act allowed a new off-river dock to be built for produce from the West Indies, and the rest of Docklands followed as landowners built enclosed docks with better security and facilities than
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#17327733060212200-549: The Elswick works at Newcastle , to produce his hydraulic machinery for cranes and bridges in 1847. His company soon received orders for hydraulic cranes from Edinburgh and Northern Railways and from Liverpool Docks , as well as for hydraulic machinery for dock gates in Grimsby . The company expanded from a workforce of 300 and an annual production of 45 cranes in 1850, to almost 4,000 workers producing over 100 cranes per year by
2300-769: The Port of Tilbury Police (formed in 1992 and a remnant of the old PLA force). The Metropolitan police have a special Marine Support Unit , formerly known as the Thames Division, which patrol and police the Thames in the Greater London area. A sixth police force in the Port may be established with the creation of the London Gateway port. 51°30′N 0°03′E / 51.5°N 0.05°E / 51.5; 0.05 Crane (machine) A crane
2400-484: The polyspastos indicate that the overall lifting capability of the Romans went far beyond that of any single crane. At the temple of Jupiter at Baalbek , for instance, the architrave blocks weigh up to 60 tons each, and one corner cornice block even over 100 tons, all of them raised to a height of about 19 m (62.3 ft). In Rome , the capital block of Trajan's Column weighs 53.3 tons, which had to be lifted to
2500-455: The 15th century also by windlasses shaped like a ship's wheel . To smooth out irregularities of impulse and get over 'dead-spots' in the lifting process flywheels are known to be in use as early as 1123. The exact process by which the treadwheel crane was reintroduced is not recorded, although its return to construction sites has undoubtedly to be viewed in close connection with the simultaneous rise of Gothic architecture. The reappearance of
2600-559: The 1990s, and bulk paper import at Convoy's Wharf in Deptford until 2000. The wider port continued to be a major centre for trade and industry, with oil and gas terminals at Coryton , Shell Haven and Canvey in Essex and the Isle of Grain in Kent. In 1992 Government privatisation policy led to Tilbury becoming a free port . The PLA ceased to be a port operator, retaining the role of managing
2700-460: The 361 t heavy Vatican obelisk in Rome. From his report, it becomes obvious that the coordination of the lift between the various pulling teams required a considerable amount of concentration and discipline, since, if the force was not applied evenly, the excessive stress on the ropes would make them rupture. Cranes were also used domestically during this period. The chimney or fireplace crane
2800-596: The Clyde and other centres from the mid-19th century. This also affected an attempt by Henry Bessemer to establish steel-making on the Greenwich Peninsula in the 1860s. The last major warship, HMS Thunderer , was launched in 1911. The volume of shipping in the Port of London supported a very extensive ship repairing industry. In 1864, when most ships coming in were built of wood and powered by sail, there were 33 ship-repairing dry docks. The largest of these
2900-426: The DLF. More sophisticated methods, such as finite element analysis or other simulation techniques, may also be used to model the crane's behavior under various loading conditions, as deemed appropriate by the designer or certifying authority.To verify the actual DLF, control load tests can be conducted on the completed crane using instrumentation such as load cells , accelerometers , and strain gauges . This process
3000-584: The East & West India Docks Company (owners of the East India, West India, and Tilbury docks), Surrey Commercial Docks Company and London & St Katharine Docks Company (owners of the London, St Katharine and Royal docks). By the beginning of the 20th century, competition and strikes led to pressure for amalgamation. A Royal Commission led to the setting up of the Port of London Authority (PLA) in 1908. In 1909,
3100-574: The London Docks together with the rest of the enclosed docks in 1909. The docks were closed to shipping in 1969 and sold to the borough of Tower Hamlets . The western portion of the London Docks was filled in with the (unrealised) intention of turning them into public housing estates. The land was still largely derelict when it was acquired in 1981 by the London Docklands Development Corporation (LDDC). It
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3200-413: The London docks. Dockers would leave work with goods hidden under their clothes, and robbers would break into warehouses at night. While tobacco, pineapples, bearskins, and other goods were all targets of thievery, the most common transgression was stealing to drink. Many reports from the early 20th century detail dockers stealing bottles of brandy or gin and drinking rather than working. More often than not,
3300-888: The Middle Ages. Unlike construction cranes where the work speed was determined by the relatively slow progress of the masons, harbor cranes usually featured double treadwheels to speed up loading. The two treadwheels whose diameter is estimated to be 4 m or larger were attached to each side of the axle and rotated together. Their capacity was 2–3 tons, which apparently corresponded to the customary size of marine cargo. Today, according to one survey, fifteen treadwheel harbor cranes from pre-industrial times are still extant throughout Europe. Some harbour cranes were specialised at mounting masts to newly built sailing ships, such as in Gdańsk , Cologne and Bremen . Beside these stationary cranes, floating cranes , which could be flexibly deployed in
3400-411: The Middle Ages. The typical harbor crane was a pivoting structure equipped with double treadwheels. These cranes were placed docksides for the loading and unloading of cargo where they replaced or complemented older lifting methods like see-saws , winches and yards . Two different types of harbor cranes can be identified with a varying geographical distribution: While gantry cranes, which pivoted on
3500-610: The PLA has implemented a plan to safeguard 50 wharves , half above and half below the Thames Barrier . In recent years there has been a resurgence in the use of the River Thames for moving cargo between terminals within the Port of London. This is seen to be in the main part due to the environmental benefits of moving such cargo by river, and as an alternative to transporting the cargo on the congested road and rail networks of
3600-454: The PLA took control of the enclosed docks from Tower Bridge to Tilbury, with a few minor exceptions such as Poplar Dock which remained as a railway company facility. It also took over control of the river between Teddington Lock and Yantlet Creek from the City corporation which had been responsible since the 13th century. The PLA head Office at Trinity Square Gardens was built by John Mowlem & Co and completed in 1919. The PLA dredged
3700-511: The PLA, London's annual trade had grown to 60 million tons (38% of UK trade) by 1939, but was mainly transferred to the Clyde and Liverpool during World War 2. After the war, London recovered, again reaching 60 million tons in the 1960s. By 1900, the wharves and docks were receiving about 7.5 million tons of cargo each; an inevitable result of the extending reach of the British Empire. Of course, because of its size and grandeur,
3800-469: The Pool were colliers meeting an increase in the demand for coal as the population of London rose. Coastal trade virtually doubled between 1750 and 1796 reaching 11,964 vessels in 1795. In overseas trade, in 1751 the pool handled 1,682 ships and 234,639 tons of goods. By 1794, this had risen to 3,663 ships and 620,845 tons. By this time, the river was lined with nearly continuous walls of wharves running for miles along both banks, and hundreds of ships moored in
3900-737: The Pool's wharves. Throughout the 19th century, a series of enclosed dock systems was built, surrounded by high walls to protect cargoes from river piracy. These included West India Docks (1802), East India Docks (1803, originating from the Brunswick Dock of 1790), London Docks (1805), Surrey Commercial Docks (1807, originating from the Howland Great Wet Dock of 1696), St Katharine Docks (1828), Royal Victoria Dock (1855), Millwall Dock (1868), Royal Albert Dock (1880), and Tilbury docks (1886). The enclosed docks were built by several rival private companies, notably
4000-536: The Port of London handles around 10% of the UK commercial shipping trade, and contributes £8.5 billion to the UK's economy . In addition to cargo, 37 cruise ships visited the Port in 2008. Once a major refiner of crude oil, today the port only imports refined products. The Kent ( BP ) and Shell Haven ( Shell ) refineries closed in 1982 and 1999, and Coryton in 2012. A number of upstream wharves remain in use. At Silvertown, for example, Tate & Lyle continues to operate
4100-453: The Port was a place of work for many labourers in late 19th and early 20th century London. While most of the dockers were casual labourers, there were skilled stevedores who loaded ships, and lightermen who unloaded cargo from moored boats via barges. While these specific dockhands found regular work, the average dockhand lived day to day, hoping he would be hired whenever a ship came in. Many times these workers would actually bribe simply for
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4200-421: The Romans at its height in the 2nd and 3rd centuries. The harbour town grew and expanded quickly. The lavish nature of goods traded in London shaped the extravagant lifestyle of its citizens and the city flourished under Roman colonization. The Roman expansion of port facilities and organisation of the London harbour have remained as the base of the London harbour. Until the beginning of the 19th century, shipping
4300-505: The Romans built the original harbour. The construction involved expanding the waterfront using wooden frames filled with dirt. Once these were in place, the wharf was built in four stages moving downstream from London Bridge . The port began to rapidly grow and prosper during the 2nd and 3rd centuries, and saw its final demise in the early 5th century with the decline in trade activity due to the Roman departure from Britain . The changes made to
4400-519: The Thames and its tributaries and canals. Major Thames-side gasworks were located at Beckton and East Greenwich , with power stations including Brimsdown , Hackney and West Ham on the River Lea and Kingston , Fulham , Lots Road , Wandsworth , Battersea , Bankside , Stepney , Deptford , Greenwich , Blackwall Point , Brunswick Wharf , Woolwich , Barking , Belvedere , Littlebrook , West Thurrock , Northfleet , Tilbury and Grain on
4500-496: The Thames via the Shadwell Basin to the east. The principal designers were the architects and engineers Daniel Asher Alexander and John Rennie . The docks specialised in high-value luxury commodities such as ivory, spices, coffee and cocoa as well as wine and wool, for which elegant warehouses and wine cellars were constructed. The system was never connected to the railway network. The Port of London Authority took over
4600-880: The Thames. Much of the disused land of the upstream London Docklands is in the process of being developed for housing and as a second financial district for London (centred on Canary Wharf ). The Port of London today comprises over 70 independently owned terminals and port facilities, directly employing over 30,000 people. These are mainly concentrated at Purfleet (with the world's largest margarine works), Thurrock , Tilbury (the Port's current main container facility), London Gateway , Coryton and Canvey Island in Essex, Dartford and Northfleet in Kent, and Greenwich, Silvertown, Barking , Dagenham and Erith in Greater London. The Port of London handles containers , timber, paper, vehicles, aggregates , crude oil , petroleum products , liquefied petroleum gas , coal, metals, grain and other dry and liquid bulk materials. In 2012 London
4700-428: The Thames. The coal requirements of power stations and gas works constituted a large proportion of London's post-war trade. A 1959 Times article states: About two-thirds of the 20 million tons of coal entering the Thames each year is consumed in nine gas works and 17 generating stations. Beckton Gas Works carbonises an average of 4,500 tons of coal every day; the largest power stations burn about 3,000 tons during
4800-606: The above definition of a crane, but are generally known as cranes, such as stacker cranes and loader cranes. Cranes were so called from the resemblance to the long neck of the bird , cf. Ancient Greek : γερανός , French grue . The first type of crane machine was the shadouf , which had a lever mechanism and was used to lift water for irrigation . It was invented in Mesopotamia (modern Iraq) circa 3000 BC. The shadouf subsequently appeared in ancient Egyptian technology circa 2000 BC. A crane for lifting heavy loads
4900-478: The autocratic societies of Egypt or Assyria . The first unequivocal literary evidence for the existence of the compound pulley system appears in the Mechanical Problems ( Mech . 18, 853a32–853b13) attributed to Aristotle (384–322 BC), but perhaps composed at a slightly later date. Around the same time, block sizes at Greek temples began to match their archaic predecessors again, indicating that
5000-482: The banks along the port made by the Romans are so substantial and long-lasting that it was hard to tell where the natural waterfront really began. However, the harbour within the Roman town was already in decline at the end of the 2nd century AD. It seems likely that a proper port developed at about this time at Shadwell , about 1 mile (1.6 km) east of the Roman town London became a very important trading port for
5100-572: The capital. Local authorities are contributing to this increase in intraport traffic, with waste transfer and demolition rubble being taken by barges on the river. The construction of the Olympic Park and Crossrail both used the river as a means of transporting cargo and waste/excavation material, and the ongoing Thames Tideway Scheme also uses the river for these purposes, as well as for transporting of its Tunnel Boring Machines as well as temporary offices. The Crossrail project alone involved
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#17327733060215200-405: The column in the middle of the structure ( Mechanica 3.5). Second, a multitude of capstans were placed on the ground around the tower, for, although having a lower leverage ratio than treadwheels, capstans could be set up in higher numbers and run by more men (and, moreover, by draught animals). This use of multiple capstans is also described by Ammianus Marcellinus (17.4.15) in connection with
5300-603: The coming of the Industrial Revolution . For many centuries, power was supplied by the physical exertion of men or animals, although hoists in watermills and windmills could be driven by the harnessed natural power. The first mechanical power was provided by steam engines , the earliest steam crane being introduced in the 18th or 19th century, with many remaining in use well into the late 20th century. Modern cranes usually use internal combustion engines or electric motors and hydraulic systems to provide
5400-492: The consequences were harsh. Five weeks of hard labour for one bottle of Hennessy brandy was not unheard of. These conditions eventually spurred Ben Tillett to lead the London Dock strike of 1889 . The workers asked for only a minuscule increase in payment, but foremen initially refused. Over time the strike grew and eventually helped to draw attention to the poor conditions of London dockhands. The strike also revitalized
5500-518: The construction of buildings. Larger cranes were later developed in the Roman Empire , employing the use of human treadwheels , permitting the lifting of heavier weights. In the High Middle Ages , harbour cranes were introduced to load and unload ships and assist with their construction—some were built into stone towers for extra strength and stability. The earliest cranes were constructed from wood, but cast iron , iron and steel took over with
5600-399: The construction of the ancient Egyptian pyramids , where about 50 men were needed to move a 2.5 ton stone block up the ramp (50 kg (110 lb) per person), the lifting capability of the Roman polyspastos proved to be 60 times higher (3,000 kg or 6,600 lb per person). However, numerous extant Roman buildings which feature much heavier stone blocks than those handled by
5700-467: The crane must not fail structurally. For stability, the sum of all moments about the base of the crane must be close to zero so that the crane does not overturn. In practice, the magnitude of load that is permitted to be lifted (called the "rated load" in the US) is some value less than the load that will cause the crane to tip, thus providing a safety margin. Under United States standards for mobile cranes,
5800-409: The cylinder and a valve regulated the amount of fluid intake relative to the load on the crane. This mechanism, the hydraulic jigger , then pulled on a chain to lift the load. In 1845 a scheme was set in motion to provide piped water from distant reservoirs to the households of Newcastle . Armstrong was involved in this scheme and he proposed to Newcastle Corporation that the excess water pressure in
5900-474: The design dynamic factor, is a critical parameter in the crane design and operation. It accounts for the dynamic effects that can increase the load on a crane's structure and components during lifting operations. These effects include: The DLF for a new crane design can be determined with analytical calculations and mathematical models following the relevant design specifications . If available, data from previous tests of similar crane types can be used to estimate
6000-415: The drop in London's trade since the 1960s is accounted for by loss of the coal trade, the gas works having closed following discovery of North Sea gas , domestic use of coal for heating being largely replaced by gas and electricity, and closure of all the coal-burning power stations above Tilbury. In 2011, when Tilbury Power Station switched fully to burning biomass, London's coal imports fell to zero. With
6100-417: The dynamic load on the crane due to vessel motion. Additionally, the stability of the vessel or platform must be considered. For stationary pedestal or kingpost mounted cranes, the moment produced by the boom, jib, and load is resisted by the pedestal base or kingpost. Stress within the base must be less than the yield stress of the material or the crane will fail. The dynamic lift factor (DLF), also known as
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#17327733060216200-469: The early 1860s. Armstrong spent the next few decades constantly improving his crane design; his most significant innovation was the hydraulic accumulator . Where water pressure was not available on site for the use of hydraulic cranes, Armstrong often built high water towers to provide a supply of water at pressure. However, when supplying cranes for use at New Holland on the Humber Estuary , he
6300-462: The engineers Vitruvius ( De Architectura 10.2, 1–10) and Heron of Alexandria ( Mechanica 3.2–5). There are also two surviving reliefs of Roman treadwheel cranes , with the Haterii tombstone from the late first century AD being particularly detailed. The simplest Roman crane, the trispastos , consisted of a single-beam jib, a winch , a rope , and a block containing three pulleys. Having thus
6400-456: The exact circumstances of the shift from the ramp to the crane technology remain unclear, it has been argued that the volatile social and political conditions of Greece were more suitable to the employment of small, professional construction teams than of large bodies of unskilled labour, making the crane preferable to the Greek polis over the more labour-intensive ramp which had been the norm in
6500-529: The figure for intraport trade was 1.9 million tonnes, making the River Thames the busiest inland waterway in the UK. DP World 's London Gateway , opened in November 2013, is an expansion of the Port of London on the north bank of the Thames in Thurrock, Essex, 30 miles (48 km) east of central London. It is a fully integrated logistics facility, comprising a semi-automated, deep-sea container terminal on
6600-506: The growth and success of the city. In the 18th and 19th centuries, it was the busiest port in the world, with wharves extending continuously along the Thames for 11 miles (18 km), and over 1,500 cranes handling 60,000 ships per year. It was a prime target for Nazi German bomber aircraft during World War II ( the Blitz ). The first evidence of a reasonable sized trading in London can be seen during Roman control of Britain, at which time
6700-456: The initial stages of construction on the ground, often within the building. When a new floor was completed, and massive tie beams of the roof connected the walls, the crane was dismantled and reassembled on the roof beams from where it was moved from bay to bay during construction of the vaults. Thus, the crane "grew" and "wandered" with the building with the result that today all extant construction cranes in England are found in church towers above
6800-412: The larger facilities in its eastern extent. As with many similar historic European ports, such as Antwerp and Rotterdam , many activities have steadily moved downstream towards the open sea as ships have grown larger and the land upriver taken over for other uses. The Port of London has been central to the economy of London since the founding of the city in the 1st century and was a major contributor to
6900-580: The lifting of the Lateranense obelisk in the Circus Maximus (c. 357 AD). The maximum lifting capability of a single capstan can be established by the number of lewis iron holes bored into the monolith. In case of the Baalbek architrave blocks, which weigh between 55 and 60 tons, eight extant holes suggest an allowance of 7.5 ton per lewis iron, that is per capstan. Lifting such heavy weights in
7000-460: The loading and unloading of freight, in construction for the movement of materials, and in manufacturing for the assembling of heavy equipment . The first known crane machine was the shaduf , a water-lifting device that was invented in ancient Mesopotamia (modern Iraq) and then appeared in ancient Egyptian technology . Construction cranes later appeared in ancient Greece , where they were powered by men or animals (such as donkeys), and used for
7100-583: The lower masts of the vessel under construction or repair. These lower masts were the largest and most massive single timbers aboard a ship, and erecting them without the assistance of either a sheer hulk or land-based masting sheer was extremely difficult. The concept of sheer hulks originated with the Royal Navy in the 1690s, and persisted in Britain until the early nineteenth century. Most sheer hulks were decommissioned warships; Chatham , built in 1694,
7200-548: The lower part of town could be used to power one of his hydraulic cranes for the loading of coal onto barges at the Quayside . He claimed that his invention would do the job faster and more cheaply than conventional cranes. The corporation agreed to his suggestion, and the experiment proved so successful that three more hydraulic cranes were installed on the Quayside. The success of his hydraulic crane led Armstrong to establish
7300-491: The maximum load. The polyspastos , when worked by four men at both sides of the winch, could readily lift 3,000 kg (6,600 lb) (3 ropes x 5 pulleys x 4 men x 50 kg or 110 lb = 3,000 kg or 6,600 lb). If the winch was replaced by a treadwheel, the maximum load could be doubled to 6,000 kg (13,000 lb) at only half the crew, since the treadwheel possesses a much bigger mechanical advantage due to its larger diameter. This meant that, in comparison to
7400-418: The more sophisticated compound pulley must have found its way to Greek construction sites by then. The heyday of the crane in ancient times came during the Roman Empire , when construction activity soared and buildings reached enormous dimensions. The Romans adopted the Greek crane and developed it further. There is much available information about their lifting techniques, thanks to rather lengthy accounts by
7500-442: The observation of the labor-saving qualities of the waterwheel with which early treadwheels shared many structural similarities. The medieval treadwheel was a large wooden wheel turning around a central shaft with a treadway wide enough for two workers walking side by side. While the earlier 'compass-arm' wheel had spokes directly driven into the central shaft, the more advanced "clasp-arm" type featured arms arranged as chords to
7600-467: The river or alongside the quays. In the late 18th century, an ambitious scheme was proposed by Willey Reveley to straighten the Thames between Wapping and Woolwich Reach by cutting a new channel across the Rotherhithe , Isle of Dogs , and Greenwich peninsulas. The three great horseshoe bends would be cut off with locks, as huge wet docks. This was not realised, though a much smaller channel,
7700-553: The same site as the UK's largest land bank for development of warehousing, distribution facilities and ancillary logistics services. It is a deep-water port able to handle the biggest container ships. The Port of London once had its own police force – the Port of London Authority Police – but is today policed by a number of forces. These are the local territorial police forces of the areas the Thames passes through (the Metropolitan , City of London , Essex and Kent forces) and
7800-554: The stability-limited rated load for a crawler crane is 75% of the tipping load. The stability-limited rated load for a mobile crane supported on outriggers is 85% of the tipping load. These requirements, along with additional safety-related aspects of crane design, are established by the American Society of Mechanical Engineers in the volume ASME B30.5-2018 Mobile and Locomotive Cranes . Standards for cranes mounted on ships or offshore platforms are somewhat stricter because of
7900-623: The third most and the Medway ports (chiefly London Thamesport ) the fifth. The number of twenty-foot equivalent units of containers handled by the Port of London exceeded two million in 2007 for the first time in the Port's history and this continued in 2008. The Port's capacity in handling modern, large ships and containers is set to dramatically expand with the completion of the London Gateway port project, which will be able to handle up to 3.5 million TEUs per year when fully completed. With around 12,500 commercial shipping movements annually,
8000-414: The transporting of 5 million tonnes of material, almost all of which is clean earth, excavated from the ground, downstream through the Port, from locations such as Canary Wharf to new nature reserves being constructed in the Thames estuary area. This also includes the re-opening of wharves or jetties for various building projects along or near the Thames, Battersea coal jetty being the most recent. In 2008,
8100-404: The treadwheel crane may have resulted from a technological development of the windlass from which the treadwheel structurally and mechanically evolved. Alternatively, the medieval treadwheel may represent a deliberate reinvention of its Roman counterpart drawn from Vitruvius ' De architectura which was available in many monastic libraries. Its reintroduction may have been inspired, as well, by
8200-568: The treadwheel crane played a pivotal role in the construction of the lofty Gothic cathedrals . Nevertheless, both archival and pictorial sources of the time suggest that newly introduced machines like treadwheels or wheelbarrows did not completely replace more labor-intensive methods like ladders , hods and handbarrows . Rather, old and new machinery continued to coexist on medieval construction sites and harbors. Apart from treadwheels, medieval depictions also show cranes to be powered manually by windlasses with radiating spokes , cranks and by
8300-436: The type of crane and its usage. Here are some example typical values: The methods for determining the DLF vary in the different crane specifications. The following formulas are examples from one specification. The working load (suspended load) is the total weight that a crane is designed to safely lift under normal operating conditions. It is W = g ⋅ ( m w l l + m
8400-571: The use of larger ships and containerisation , the importance of the upstream port declined rapidly from the mid-1960s. The enclosed docks further up river declined and closed progressively between the end of the 1960s and the early 1980s. Trade at privately owned wharves on the open river continued for longer, for example with container handling at the Victoria Deep Water Terminal on the Greenwich Peninsula into
8500-475: The use of several smaller stones more practical than fewer larger ones. In contrast to the archaic period with its pattern of ever-increasing block sizes, Greek temples of the classical age like the Parthenon invariably featured stone blocks weighing less than 15–20 metric tons. Also, the practice of erecting large monolithic columns was practically abandoned in favour of using several column drums. Although
8600-467: The vaulting and below the roof, where they remained after building construction for bringing material for repairs aloft. Less frequently, medieval illuminations also show cranes mounted on the outside of walls with the stand of the machine secured to putlogs . In contrast to modern cranes, medieval cranes and hoists — much like their counterparts in Greece and Rome — were primarily capable of
8700-538: The wall. Additionally, the crane master who usually gave orders at the treadwheel workers from outside the crane was able to manipulate the movement laterally by a small rope attached to the load. Slewing cranes which allowed a rotation of the load and were thus particularly suited for dockside work appeared as early as 1340. While ashlar blocks were directly lifted by sling, lewis or devil's clamp (German Teufelskralle ), other objects were placed before in containers like pallets , baskets , wooden boxes or barrels . It
8800-477: The wheel rim, giving the possibility of using a thinner shaft and providing thus a greater mechanical advantage. Contrary to a popularly held belief, cranes on medieval building sites were neither placed on the extremely lightweight scaffolding used at the time nor on the thin walls of the Gothic churches which were incapable of supporting the weight of both hoisting machine and load. Rather, cranes were placed in
8900-451: The whole port basin came into use by the 14th century. A sheer hulk (or shear hulk) was used in shipbuilding and repair as a floating crane in the days of sailing ships , primarily to place the lower masts of a ship under construction or repair. Booms known as sheers were attached to the base of a hulk's lower masts or beam, supported from the top of those masts. Blocks and tackle were then used in such tasks as placing or removing
9000-401: The world submarine communication cable industry for decades with works at Greenwich , Silvertown, North Woolwich , Woolwich and Erith . For centuries London was the major centre of shipbuilding in Britain (for example at Blackwall Yard , London Yard , Samuda Yard , Millwall Iron Works , Thames Ironworks , Greenwich , and Deptford and Woolwich dockyards), but declined relative to
9100-571: The world's largest cane sugar refinery , originally served by the West India Docks but now with its own cargo handling facilities. Many wharves as far upstream as Fulham are used for the handling of aggregates brought by barge from facilities down river. Riverside sites in London are under intense pressure for prestige housing or office development, and as a consequence the Greater London Authority in consultation with
9200-545: Was Langley's Lower Dock at Deptford Green, which was 460 ft (140 m) in length. While the building of large ships ceased with the closure of the Thames Ironworks and Shipbuilding Company at Leamouth in 1912, the ship repairing trade continued to flourish. Although by 1930 the number of major dry docks had been reduced to 16, highly mechanised and geared to the repair of iron and steel-hulled ships. There were also numerous power stations and gas works on
9300-467: Was developed by the Ancient Greeks in the late 6th century BC. The archaeological record shows that no later than c. 515 BC distinctive cuttings for both lifting tongs and lewis irons begin to appear on stone blocks of Greek temples. Since these holes point at the use of a lifting device, and since they are to be found either above the center of gravity of the block, or in pairs equidistant from
9400-412: Was formed in 1800, and work on the docks began in 1801. In 1864 they were amalgamated with St Katharine Docks . The London Docks occupied a total area of about 30 acres (120,000 m), consisting of Western and Eastern docks linked by the short Tobacco Dock . The Western Dock was connected to the Thames by Hermitage Basin to the south west and Wapping Basin to the south. The Eastern Dock connected to
9500-481: Was handled entirely within the Pool of London on the stretch of the River Thames along Billingsgate on the south side of the City of London . All imported cargoes had to be delivered for inspection and assessment by Customs Officers, giving the area the name of " Legal Quays ". The Pool saw a phenomenal increase in both overseas and coastal trade in the second half of the 18th century. Two-thirds of coastal vessels using
9600-475: Was subsequently redeveloped with over 1,000 individual properties centred on the old Tobacco Dock and Shadwell Basin . The controversial " Fortress Wapping " printing works of Rupert Murdoch 's News International corporation was constructed on the northern half of the infilled Western Dock. Hermitage Basin and Shadwell Basin survive. Wapping Basin is now a sports pitch and some of the Eastern Dock site
9700-461: Was the first of only three purpose-built vessels. There were at least six sheer hulks in service in Britain at any time throughout the 1700s. The concept spread to France in the 1740s with the commissioning of a sheer hulk at the port of Rochefort. A lifting tower similar to that of the ancient Romans was used to great effect by the Renaissance architect Domenico Fontana in 1586 to relocate
9800-444: Was the second largest port in the United Kingdom by tonnage handled (43.7 million), after Grimsby and Immingham (60 million). The Port of London however handles the most non-fuel cargo of any port in the UK (at 32.2 million tonnes in 2007). Other major rival ports to London in the country are Felixstowe and Southampton , which handle the most and second-most number of containers of British ports; in 2012 London handled
9900-441: Was unable to do this, because the foundations consisted of sand. He eventually produced the hydraulic accumulator, a cast-iron cylinder fitted with a plunger supporting a very heavy weight. The plunger would slowly be raised, drawing in water, until the downward force of the weight was sufficient to force the water below it into pipes at great pressure. This invention allowed much larger quantities of water to be forced through pipes at
10000-413: Was used to swing pots and kettles over the fire and the height was adjusted by a trammel . With the onset of the Industrial Revolution the first modern cranes were installed at harbours for loading cargo. In 1838, the industrialist and businessman William Armstrong designed a water-powered hydraulic crane . His design used a ram in a closed cylinder that was forced down by a pressurized fluid entering
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