Project Report

TYPES OF CRANES

MUHAMMAD UMAR

Department of Mechanical Engineering.

SummaryThe project report on the topic of cranes and its types contains the following headings:-1. Introduction of cranes1. Historical background of cranes1. Basic structure of cranes1. Diagramatic explanation of cranes1. Mechanics and working of cranes1. Types of cranes1. Improvements in cranes with time1. Industrial applications of cranes1. Local or domestic use of cranes1. Advantages of cranes1. Disadvantages and accidents related to cranes1. Care about cranes 1. Future horizons

PrefaceWorkshop being an advanced and all time progessive area has so much applications that one can hardly imagine.This report regarding the cranes and its types has sufficient material to get an over view of the topic with respect to old present and future ages.During the making of this book the main objectives in my mind were:-1. To cover the basic information that how cranes came into being, got modified and lead to the present form.1. To present the basic structure of cranes.1. To show the working mechanism and mechanics of cranes.1. To over view the applications of cranes.1. To discuss about various types of cranes.1. To develop a better understanding of the topic with respect to our subject.The special features of this publications are:-1. Up to date information.1. Many basic structural study with comprehensive details.1. Starting from ancient root moved to modern cranes.1. Emphasis on understanding of cranes and its types in modern world.1. Examples from daily life.1. All terms used are purely technical.1. Resource CD and PPT files for better understanding of the topic.

ObjectivesWhile writing this book the objectives in my mind were:-

1. To cover the basic information that how cranes came into being, got modified and lead to the present form.1. To present the basic structure of cranes.1. To show the working mechanism and mechanics of cranes.1. To over view the industrial usage of cranes.1. To over view the local use of cranes in our life.1. To discuss about various types of cranes in detail.1. To Develop basic movement of Crane with

IntroductionA crane is a lifting machine, generally equipped with a winder (also called a wire rope drum), 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 a human. Cranes are commonly employed in the transport industry for the loading and unloading of freight, in the construction industry for the movement of materials and in the manufacturing industry for the assembling of heavy equipment.Archimedes said:Give me a lever long enough and a place to stand and I will lift the worldThis statement from the ancient times is self explaining that cranes either in simplest form were thought and were present in all times. The common thinking that any big sized machine is a crane is not that much true. According to definition any simple or complex machine that may be small or big if helps in carrying load and heavy operations, than it is a crane. Cranes are of various types according to motility, shapes, working etc.

Historical view of cranesThe first construction cranes were invented by the Ancient Greeks and were powered by men or beasts of burden, such as donkeys. These cranes were used for the construction of tall buildings. Larger cranes were later developed, 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 and steel took over with 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 a much greater lifting capability than was previously possible, although manual cranes are still utilised where the provision of power would be uneconomic.Cranes exist in an enormous variety of forms 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, and the largest floating cranes, used to build oil rigs and salvage sunken ships.In Ancient GreeceThe earliest known are:-Greco-Roman Trispastos ("Three-pulley-crane"), the simplest crane type (150 kg load)

Greco-Roman Pentaspastos ("Five-pulley-crane"), a medium-sized variant (ca. 450 kg load)The crane for lifting heavy loads was invented 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 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 lead to a widespread replacement of ramps as the main means of vertical motion. For the next two hundred years, Greek building sites witnessed a sharp drop in the weights handled, as the new lifting technique made the use of several smaller stones more practical than of fewer larger ones. In contrast to the archaic period with its tendency to ever-increasing block sizes, Greek temples of the classical age like the Parthenon invariably featured stone blocks weighing less than 15-20 tons. Also, the practice of erecting large monolithic columns was practically abandoned in favour of using several column drums. Although 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 more preferable to the Greek polis than the more labour-intensive ramp which had been the norm in the autocratic societies of Egypt or Assyria. The first unequivocal literary evidence for the existence of the compound pulley 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 the more sophisticated compound pulley must have found its way to Greek construction sites by then.In Ancient RomeReconstruction of a 10.4m high Roman Polyspastos powered by a treadwheel at Bonn, GermanyThe 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 furtherThe simplest Roman crane, the Trispastos, consisted of a single-beam jib, a winch, a rope, and a block containing three pulleys. Having thus a mechanical advantage of 3:1, it has been calculated that a single man working the winch could raise 150kg (3 pulleys x 50kg = 150), assuming that 50kg 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 the maximum load. The Polyspastos, when worked by four men at both sides of the winch, could already lift 3000kg (3 ropes x 5 pulleys x 4 men x 50kg = 3000kg). In case the winch was replaced by a treadwheel, the maximum load even doubled to 6000kg 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 the construction of the Egyptian Pyramids, where about 50 men were needed to move a 2.5 ton stone block up the ramp (50kg per person), the lifting capability of the Roman Polyspastos proved to be 60 times higher (3000kg per person). However, numerous extant Roman buildings which feature much heavier stone blocks than those handled by 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 the corner cornices blocks even over 100 tons, all of them raised to a height of about 19 m. In Rome, the capital block of Trajan's Column weighs 53.3 tons, which had to be lifted to a height of about 34 m. It is assumed that Roman engineers lifted these extraordinary weights by two measures: 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 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). In the Middle AgesSmall-scale reconstruction of the medieval gantry crane at Brugge harbor

Medieval port crane with building overhanging in the former Hanse town of Danzig (Gdask).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 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, Brugge 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 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 site and harbors. Apart from treadwheels, medieval depictions also show cranes to be powered manually by windlasses with radiating spokes, cranks and by 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 the treadwheel crane may have resulted from a technological development of the windlass from which the treadwheel structurally and mechanically evolved. Its reintroduction may have been inspired, as well, by the observation of the labor-saving qualities of the waterwheel with which early treadwheels shared many structural similarities. Firstly when big sized cranes were there the movement was locked to two dimentional but with time need and progress cranes with three dimentional free movements were formed and modified. The development of slewing level luffing cranes from 18561956

Another type of crane or similar to it is a derric and it may be explained as:-A derrick is a lifting device composed of one mast or pole which is hinged freely at the bottom. It is controlled by lines (usually four of them) powered by some means such as man-hauling or motors, so that the pole can move in all four directions.In old times there was no discrimination between the two but now they are studied as two different tools but their progress is inter relivant so in the history section they will be treated as same.

The development of floating cranes 19051936

Enormous advances now mean that huge loads can be lifted byoffshore- and derricking- and slewing cranes where hoisting capacitiesof 2000 tons or more are routine. Figure illustrate thedevelopment of cranes over relatively short periods of time and showthe vast differences in size and lifting capacity. figureshow typical cranes that are in use today.Mechanics and working of cranesBefore entering the study of the working of a crane we will firstly over view its structure:

Figure showing the structure of a craneThe 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 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 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 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.

Mechanics and operationIn contrast to modern cranes, medieval cranes and hoists - much like their counterparts in Greece and Rome - were primarily capable of 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 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 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 treadwheels which normally prevented the wheel from accelerating beyond control.

Harbor usageAccording to the present state of knowledge unknown in antiquity, stationary harbor cranes are considered a new development of 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 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. Interestingly, 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 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 4m or larger were attached to each side of the axle and rotated together. Today, according to one survey, fifteen treadwheel harbor cranes from pre-industrial times are still extant throughout Europe. Beside these stationary cranes, floating cranes which could be flexibly deployed in the whole port basin came into use by the 14th century.

Mechanical principles

Cranes can mount many different utensils depending on load (left). Cranes can be remote-controlled from the ground, allowing much more precise control, but without the view that a position atop the crane provides (right).

The stability of a mobile construction crane can be jeopardized when outriggers sink into soft soil, which can result in the crane tipping over.There are two major considerations in the design of cranes. The first is that the crane must be able to lift a load of a specified weight and the second is that the crane must remain stable and not topple over when the load is lifted and moved to another location.

Lifting capacityCranes illustrate the use of one or more simple machines to create mechanical advantage. The lever. A balance crane contains a horizontal beam (the lever) pivoted about a point called the fulcrum. The principle of the lever allows a heavy load attached to the shorter end of the beam to be lifted by a smaller force applied in the opposite direction to the longer end of the beam. The ratio of the load's weight to the applied force is equal to the ratio of the lengths of the longer arm and the shorter arm, and is called the mechanical advantage. The pulley. A jib crane contains a tilted strut (the jib) that supports a fixed pulley block. Cables are wrapped multiple times round the fixed block and round another block attached to the load. When the free end of the cable is pulled by hand or by a winding machine, the pulley system delivers a force to the load that is equal to the applied force multiplied by the number of lengths of cable passing between the two blocks. This number is the mechanical advantage. The hydraulic cylinder. This can be used directly to lift the load or indirectly to move the jib or beam that carries another lifting device.Cranes, like all machines, obey the principle of conservation of energy. This means that the energy delivered to the load cannot exceed the energy put into the machine. For example, if a pulley system multiplies the applied force by ten, then the load moves only one tenth as far as the applied force. Since energy is proportional to force multiplied by distance, the output energy is kept roughly equal to the input energy (in practice slightly less, because some energy is lost to friction and other inefficiencies).

StabilityFor stability, the sum of all moments about any point such as the base of the crane must equate to zero. 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 (providing a safety margin).Under US standards for mobile cranes, 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.Standards for cranes mounted on ships or offshore platforms are somewhat stricter because of 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 created 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. As the purpose of this publication is solely to study the types of cranes thats why the mechanics section has got only a birds eye view.

Types of cranesThey are commonly used in the construction industry and in the manufacturing of heavy equipment. Cranes for construction are normally temporarystructures, either fixed to the ground or mounted on a purpose built vehicle.They can either be controlled from an operator in a cab that travels along with the crane, by a push button pendant control station, or by radio type controls. The crane operator is ultimately responsible for the safety of the crews and the crane. The most basic types of cranes

The few main types of cranesThe cranes visible in the figure are showing the history as well as the advancement in cranes with time. Although the concept about cranes in ones mind would be as abig machine but the basic type of crane can break the the concept.On the basis of modern crane study and advancement there are two basic types of cranes:-1. Fixed Cranes2. Mobile or Movable CranesNow we will discuss the two types of cranes in detail:-

Fixed cranesAs the name indicates, these cranes would not show any appreciable movement. Exchanging mobility i.e. the ability to move; for the ability to carry greater loads and reach greater heights as compare to any other type of cranes,and it is due to increased stability, these types of cranes are characterised that they (or at least their main structure) does not move during the period of use. However, many can still be assembled and disassembled and sometimes show a little movement too but again it is not appreciable to a limit that we may say them mobile. Mobile cranes are so much easy to use and move but the importance and use of fixed cranes hasnt lost its importance and we see them everywhere.The most important by use and stability are:-1. Tower crane

2. Self-erecting crane

3. Telescopic crane

4. Hammerhead crane

5. Level luffing crane

6. Gantry crane

7. Overhead crane

8. Deck crane

9. Jib crane

10. Bulk-handling crane

11. Loader crane

12. Stacker crane

Tower cranesThe tower crane is a modern form of balance crane. Fixed to the ground (and sometimes attached to the sides of structures as well), tower cranes often give the best combination of height and lifting capacity and are used in the construction of tall buildings. The jib (colloquially, the 'boom') and counter-jib are mounted to the turntable, where the slewing bearing and slewing machinery are located. The counter-jib carries a counterweight, usually of concrete blocks, while the jib suspends the load from the trolley. The Hoist motor and transmissions are located on the mechanical deck on the counter-jib, while the trolley motor is located on the jib. The crane operator either sits in a cabin at the top of the tower or controls the crane by radio remote control from the ground. In the first case the operator's cabin is most usually located at the top of the tower attached to the turntable, but can be mounted on the jib, or partway down the tower. The lifting hook is operated by using electric motors to manipulate wire rope cables through a system of sheaves.

In order to hook and unhook the loads, the operator usually works in conjunction with a signaller (known as a 'rigger' or 'swamper'). They are most often in radio contact, and always use hand signals. The rigger directs the schedule of lifts for the crane, and is responsible for the safety of the rigging and loads.A tower crane is usually assembled by a telescopic jib (mobile) crane of greater reach (also see "self-erecting crane" below) and in the case of tower cranes that have risen while constructing very tall skyscrapers, a smaller crane (or derrick) will often be lifted to the roof of the completed tower to dismantle the tower crane afterwards.It is often claimed that a large fraction of the tower cranes in the world are in use in Dubai. And definitely it represents their progressing rate.

Self-erecting crane

Generally a type of tower crane, these cranes, also called self-assembling or "Kangaroo" cranes, lift themselves off the ground using jacks, allowing the next section of the tower to be inserted at ground level or lifted into place by the partially erected crane itself. They can thus be assembled without outside help, or can grow together with the building or structure they are erecting.

With a combination of superior reach, safer operating techniques and quiet operation, selferecting cranes outperform telehandlers. The cranes are used in areas not accessible to a telehandler and reach across an entire jobsite instead of one area, thus enhancing safety. Radio remote control allows operation close to the load to accurately pick and place materials. Users benefit from the cranes ability to work in environmentally sensitive areas due to electric power operation from a genset that is quieter than mobile alternatives.

Telescopic cranes

A telescopic crane has a boom that consists of a number of tubes fitted one inside the other. A hydraulic or other powered mechanism extends or retracts the tubes to increase or decrease the total length of the boom. These types of booms are often used for short term construction projects, rescue jobs, lifting boats in and out of the water, etc. The relative compactness of telescopic booms make them adaptable for many mobile applications.

Note that while telescopic cranes are not automatically mobile cranes, many of them are. These are often truck-mounted.

Hammer head cranes

The "hammerhead", or giant cantilever, crane is a fixed-jib crane consisting of a steel-braced tower on which revolves a large, horizontal, double cantilever; the forward part of this cantilever or jib carries the lifting trolley, the jib is extended backwards in order to form a support for the machinery and counter-balancing weight. In addition to the motions of lifting and revolving, there is provided a so-called "racking" motion, by which the lifting trolley, with the load suspended, can be moved in and out along the jib without altering the level of the load. Such horizontal movement of the load is a marked feature of later crane design. These cranes are generally constructed in large sizes, up to 350 tons. The design of hammerkran evolved first in Germany around the turn of the 19th century and was adopted and developed for use in British shipyards to support the battleship construction program from 1904-1914. The ability of the hammerhead crane to lift heavy weights was useful for installing large pieces of battleships such as armour plate and gun barrels. Giant cantilever cranes were also installed in naval shipyards in Japan and in the USA. The British Government also installed a giant cantilever crane at the Singapore Naval Base (1938) and later a copy of the crane was installed at Garden Island Naval Dockyard in Sydney (1951). These cranes provided repair support for the battle fleet operating far from Great Britain.The principal engineering firm for giant cantilever cranes in the British Empire was Sir William Arrol & Co Ltd building 14. Of around 60 built across the world few remain; 7 in England and Scotland of about 15 worldwide. The Titan Clydebank is one of the 4 Scottish cranes on the Clydebank and preserved as a tourist attraction.

Level luffing craneNormally a crane with a hinged jib will tend to have its hook also move up and down as the jib moves (or luffs). A level luffing crane is a crane of this common design, but with an extra mechanism to keep the hook level when luffing.

A level luffing crane is a crane mechanism where the hook remains at the same level whilst luffing; moving the jib up and down, so as to move the hook inwards and outwards relative to the base.[1]Some types of crane are inherently level luffing: those with a fixed horizontal jib, such as gantry, hammerhead or the fixed-jib tower cranes commonly used in construction. Usually though, the description is only applied to those with a luffing jib that have some additional mechanism applied to keep the hook level when luffing.

Level luffing is most important when careful movement of a load near ground level is required, such as in construction or shipbuilding. This partially explains the popularity of fixed horizontal jibs in these fields.

Toplis cable luffing

Stothert & Pitt crane with Toplis gear An early form of level luffing gear was the "Toplis" design, invented by a Stothert & Pitt engineer in 1914.[2][3] This is also a purely mechanical linkage, arranged by the reeving of the hoist cables to the jib over pulleys at the crane's apex above the cab, so that luffing the jib upwards allows more free cable and lowers the hook to compensate.Horse-head jibs

Horse-head jib, showing the level position of the hook

Horse-head design The usual mechanism for level luffing in modern cranes is to add an additional "horse head" section to the top of the jib. By careful design of the geometry, this keeps level merely by the linked action of the pivots.[4]Powered level luffingAs cranes and their control systems became more sophisticated, it became possible to control the level of luffing directly, by winching the hoist cable in and out as needed. The first of these systems used mechanical clutches between luffing and hoist drums, giving simplicity and a "near level" result.[5]Later systems have used modern electronic controls and quickly reversible motors with good slow-speed control to the hoist winch motors, so as to give a positioning accuracy of inches. Some early systems used controllable hydraulic gearboxes to achieve the same result, but these added complexity and cost and so were only popular where high accuracy was needed, such as for shipbuilding.Luffing cabsLuffing mechanisms have also been applied to the driver's cab being mounted on its own jib, following the movement of the crane's main jib [6] These are used for tasks such as ship unloading, where the view from the driver's cab is greatly improved by cantilevering it forwards and over the ship.

Gantry craneA gantry crane has a hoist in a fixed machinery house or on a trolley that runs horizontally along rails, usually fitted on a single beam (mono-girder) or two beams (twin-girder). The crane frame is supported on a gantry system with equalized beams and wheels that run on the gantry rail, usually perpendicular to the trolley travel direction. These cranes come in all sizes, and some can move very heavy loads, particularly the extremely large examples used in shipyards or industrial installations. A special version is the container crane (or "Portainer" crane, named by the first manufacturer), designed for loading and unloading ship-borne containers at a port.Both overhead travelling cranes and gantry cranes are types of crane which lift objects by a hoist which is fitted in a 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 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 fro 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 travelling cranes and gantry cranes 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.

Container craneA 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 CranesWorkstation 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.Rail Mounted or EOT Gantry CranesElectrical Overhead Travelling (EOT) cranes or Gantry Cranes 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. Most are electrically powered and painted safety yellow.

Overhead craneAlso known as a 'suspended crane', this type of crane work very similar to a gantry crane but instead of the whole crane moving, only the hoist / trolley assembly moves in one direction along one or two fixed beams, often mounted along the side walls or on elevated columns in the assembly area of factory. Some of these cranes can lift very heavy loads.An overhead crane is a type of crane where the hook-and-line mechanism runs along a horizontal beam that runs along two widely separated rails. Often it is in a long factory building and runs along rails along the building's two long walls. It is similar to a gantry crane.An overhead crane typically consists of three important parts:1. The hoist, providing up/down motion to lift items.2. The trolley, providing left/right motion for the hoist and load.3. The bridge, providing back/forward motion for trolley, hoist, and load.This is permanently installed in a factory, shop, or warehouse to move items not moveable by humans or forklifts.

The most common overhead crane use is in the steel industry. Every step of steel, until it leaves a factory as a finished product, the steel is handled by an overhead crane. Raw materials are poured into a furnace by crane, hot steel is stored for cooling by an overhead crane, the finished coils are lifted and loaded onto trucks and trains by overhead crane, and the fabricator or stamper uses an overhead crane to handle the steel in his factory. The automobile industry uses overhead cranes for handling of raw materials. Smaller workstation cranes handle lighter loads in a work-area, such as CNC mill or saw.

Deck crane

Located on the ships and boats, these are used for cargo operations or boat unloading and retrieval where no shore unloading facilities are available. Most are diesel-hydraulic or electric-hydraulic

The most advanced form of a deck crane is a GLB deck crane. GLB electro-hydraulic deck cranes are designed for bulk carriers. We focused on giving the GLB a robust design, and excellent control and operational properties. The range covers lifting capacities from 25 to 36 tonnes, with 18-30 m outreaches. GLB cranes are built from modules, and are easy to maintain and install.

General design: GLB cranes are designed to meet the rules of all recognised classification societies and regulatory bodies. They are designed to work in the tough conditions that go with grab and log handling. The cranes have a stepless control system, and hoisting, luffing and slewing motions are independent of each other. This means that at their maximum capacity GLB cranes can operate at full speed using all three movements at the same time. These cranes can be supplied with the tools needed for handling particular cargoes.

Jib craneA jib crane is a type of crane where a horizontal member (jib or boom), supporting a moveable hoist, is fixed to a wall or to a floor-mounted pillar. Jib cranes are used in industrial premises and on military vehicles. The jib may swing through an arc, to give additional lateral movement, or be fixed. Similar cranes, often known simply as hoists, were fitted on the top floor of warehouse buildings to enable goods to be lifted to all floors.

Floor Mounted Jib Crane Up to 5 Ton Standard Capacities Up to 20 Feet Span Unlimited Custom Design Wall Mounted Jib Crane Up to 5 Ton Standard Capacities Up to 20 Feet Span Unlimited Custom Design Special Application Jib Cranes Up to 1 Ton Capacity Up to 16 Feet Span 3 Different Mounting Styles: Floor, Ceiling and Wall.Jib extension on a scotch derrick

By linking the extension to the main jib (in the example above there is a rigid tie-bar between the top of the pillar and the end of the extension) you can arrange for the load to remain at about the same height as the crane jib is luffed, that is if you lift the main jib the load moves closer to the crane but remains at the same level.

This was common on dockside cranes, although the example shown below, taken from a 1930s book on engineering, is a very large crane, probably based on one at a ship yard rather than a quay. These are known as 'horses heads', at least by sailors.

Bulk-handling craneBulk-handling cranes are designed from the outset to carry a shell grab or bucket, rather than using a hook and a sling. They are used for bulk cargoes, such as coal, minerals, scrap metal etc.

A bulk-handling crane is one that, instead of a simple hook that can handle a range of slung loads, has an integral grab for lifting bulk cargoes such as coal, mineral ore etc.Where the grab is a two-piece hinged bucket, it is known as a shell grab or shell bucket. Working the grab requires extra cables from the crane jib, so requires a specialised design of crane throughout, not merely an attachment. Some grabs use 2 cables for lift and control, others use 4.In 1927, Stothert & Pitt of Bath, Somerset produced the first specialised bulk-handling crane. This was to unload coal at Barking power station in London.

Orange-peel grabsWhere a cargo is coarser in size than minerals, commonly for scrap metal, then an orange-peel grab may be used instead of a shell. These have six or eight segments of "peel" independently hinged around a central core. They are better able to grab at an uneven load, rather than just scooping at small pieces. If the load is made of long thin pieces, a grab may also be able to carry far more than a single "grabful" at one time.Although orange-peel grabs may be hung from cables on a jib, they're also commonly mounted directly onto a jib. This is more suitable for grabbing at awkward loads that might otherwise tend to tip a hanging grab over. They may also use hydraulics to control the segments rather than weight and hoist cables.

Kangaroo cranesAnother of Stothert & Pitt's innovations was the kangaroo crane. Rather than slewing (rotating) the crane to reach the delivery hopper on-shore, a kangaroo crane has its own in-built hopper beneath the jib, that slews with it as the crane rotates. Dumping the grab contents into the hopper now only requires the quicker luffing movement, without needing to slew for each load.

The term "kangaroo crane" has also been applied more recently to jumping cranes, tower cranes used in the construction of skyscrapers that are capable of raising their towers as construction grows upwards.

Loader craneA loader crane (also called a knuckle-boom crane or articulating crane ) is a hydraulically-powered articulated arm fitted to a truck or trailer, and is used for loading/unloading the vehicle. The numerous jointed sections can be folded into a small space when the crane is not in use. One or more of the sections may be telescopic. Often the crane will have a degree of automation and be able to unload or stow itself without an operator's instruction. The numerous sections can be folded into a small space when the crane isnt in use.

Unlike most cranes, the operator must move around the vehicle to be able to view his load; hence modern cranes may be fitted with a portable cabled or radio-linked control system to supplement the crane-mounted hydraulic control levers.In the UK and Canada, this type of crane is almost invariably known colloquially as a "Hiab", partly because this manufacturer invented the loader crane and was first into the UK market, and partly because the distinctive name was displayed prominently on the boom arm.A rolloader' crane is a loader crane mounted on a chassis with wheels. This chassis can ride on the trailer. Because the crane can move on the trailer, it can be a light crane, so the trailer is allowed to transport more goods.

Stacker craneA crane with a forklift type mechanism used in automated (computer controlled) warehouses (known as an automated storage and retrieval system (AS/RS)). The crane moves on a track in an aisle of the warehouse. The fork can be raised or lowered to any of the levels of a storage rack and can be extended into the rack to store and retrieve product.

The product can in some cases be as large as an automobile. Stacker cranes are often used in the large freezer warehouses of frozen food manufacturers. This automation avoids requiring forklift drivers to work in below freezing temperatures every day.This crane is a machine integrated into an Automated Storage/Retrieval System, also known as AS/RS. The AS/RS are computer-controlled systems for storing and retrieving products in manufacturing warehouses and facilities. The stacker cranes role in the system is to transfer large unit loads from a specific storage slot to a pickup or delivery station. The stacker crane is a large carriage that is built directly between the aisles of the AS/RS. In a highly sophisticated system, multiple stacker cranes can be assigned to one aisle. It can be built to move either vertical or parallel in the aisle.

OCS stacker crane is highly reputed for the stable automatic pallet transportation. Well-equipped option for single or double load devices, it allows the maximum throughput with high-speed and stable bay performance.Single-mast stacker craneThe single-mast stacker crane MAGITO now offers the familiar top performance of the Mustang for heights of up to 18 m. A new construction concept for the mast head provides for additional stability, which allows the device to optimally bear the high speed and accelerations. The MAGITO can be combined with all standard load handling devices and is thus suitable for all applications between 14 and 18 m.Depth stacker-cranesSingle or double depth stacker-cranes Mono or bi-pallet stacker-cranes Curve stacker-crane (transferring, switching)

A complement to traditional storage functions, these technologies are perfectly suited to : - Negative or controlled temperature warehouses, - Bufferstock with rapid turnover, - Supply of order preparation stations integrated in or exterior to storage,

Mobile CranesThese are the new type of cranes and are movable to a great extent. This movement is of the crane from one place to another as well as the movement of crane basic work tool. The most basic type of crane consists of a steel truss or telescopic boom mounted on a mobile platform, which could be a rail, wheeled, or even on a cat truck. The boom is hinged at the bottom and can be either raised or lowered by cables or hydraulic cylinders. The main types of mobile or movable cranes are:-1. Truck-mounted crane

2. Sidelift crane

3. Rough terrain crane

4. All terrain crane

5. Crawler crane

6. Railroad crane

7. Floating crane

8. Aerial crane

Now we will discuss each type in detail:

Truck-mounted craneCranes mounted on a rubber tire truck will provide great mobility. Outriggers that extend vertically or horizontally are used to level and stabilize the crane during hoisting. A crane mounted on a truck carrier provides the mobility for this type of crane. Generally, these cranes are able to travel on highways, eliminating the need for special equipment to transport the crane. When working on the jobsite, outriggers are extended horizontally from the chassis then vertically to level and stabilize the crane while stationary and hoisting. Many truck cranes have slow-travelling capability (a few miles per hour) while suspending a load. Great care must be taken not to swing the load sideways from the direction of travel, as most anti-tipping stability then lies in the stiffness of the chassis suspension. Most cranes of this type also have moving counterweights for stabilization beyond that provided by the outriggers. Loads suspended directly aft are the most stable, since most of the weight of the crane acts as a counterweight. Factory-calculated charts (or electronic safeguards) are used by crane operators to determine the maximum safe loads for stationary (outriggered) work as well as (on-rubber) loads and travelling speeds.

Truck cranes range in lifting capacity from about 14.5 US tons to about 1300 US tons. 1930s and 1940s small mobile motor cranes

By the early 1930s motor lorries equipped with petrol engined cranes were in regular use, the railways used them in larger goods yards (often for handling containers), those seen on non-railway work were usually owned by a contractor and hired out with its driver as required. There were some apparently purpose built vehicles in which the driver could turn his seat round to operate the crane but there norm seems to have been a crane unit with operators seat (in the open, cabs came in in the later 1930s but open seats were seen into the 1960s) bolted to the rear of a lorry chassis. For people working on OO scale the Airfix 'RAF Recovery Set' includes a crane that saw widespread use in railway yards after the second world war (and the associated articulated lorry tractor was also a type used by BR, although not with the long RAF trailer). As far as I am aware nothing similar is yet available in N.

Modern diesel engined cranes, with hydraulic rams to lift and sometimes to extend the jib and an electric or hydraulic motor to wind in the hoisting cable, started to appear in the late 1950s. These use a compressor to provide the hydraulic pressure and because compressors heat up the fluid they use oil rather than water to avoid the risk of steam forming. The example shown below is traced from a photo taken in the 1950s showing such a crane being used to load coke into road lorries. Note there is limited articulation and little use of the hydraulics, the jib is raised and lowered by the two rams behind the cab, and the grab is operated by hydraulics, but the rest is all mechanical linkages. Note the double wheels at the front, single at the rear.

Early mobile hydraulic craneThe application of hydraulics to produce more complex articulated and extending jibs had to wait for general engineering to catch up and produce sufficiently accurate parts and effective seals but by the 1980s most rail mounted cranes were of this general type.

Note that by the mid 1930s cranes were by law clearly marked with their safe working load, usually in the form SWL 1 TON written in white on both sides of the jib (the law requiring the safe load to be established had been passed in 1844 but it was the 1880s before the tests produced meaningful results). The size of the lettering varied depending on the type of crane, small hand cranes where the operator was standing close to the jib might use lettering as small as two inches high but for large cranes with a cab the lettering was usually the full height of the jib side. In the 1920s and less commonly in the 1930s some cranes had something like 3 TONS written on the side but the safe working load was a legal requirement so the SWL abbreviation soon became standard.

Up until the 1960s for regular heavy loads the best option was the overhead gantry crane, some were fixed in position, others mounted on a bridge across two parallel raised rails (technically 'travelling gantry cranes'). Larger railway yards often had a gantry crane, some were fixed but most I believe were the travelling type (often called a Goiliath crane by railwaymen).

Kibri do a rather nice vintage gantry crane (B-7452), this has a fixed base and a covered gantry with railed walk ways and can span two tracks. Vollmer offer a modern tubular metal fixed gantry crane (7901), which would look well on any layout set after the 1960s, and as mentioned elsewhere they also offer the only really convincing ISO container handling crane (7905). The British firm Knightwing offer a neat cast white metal small fixed gantry crane well suited to industrial use.

Two types which the modeller might attempt are the very small gantry or overhead conveyor and the very large travelling gantry crane suitable for a heavy engineering factory or larger railway goods yard. The sketch below shows the most basic form, a simple I section rail with a carriage running on the bottom web that might be used in an engineering works to lift heavy items on and off railway wagons (technically this is an 'overhead conveyor' rather than a crane). At a works the rail could extend into a building through a doorway (the doors being cut away to allow this) so items could be transferred to and from inside the building and the railway wagons. Note this requires two doors (usually sliding rather than hinged), one either side of the top rail.

Sidelift craneA sidelifter crane is a road-going truck or semi-trailer, able to hoist and transport ISO standard containers. Container lift is done with parallel crane-like hoists, which can lift a container from the ground or from a railway vehicle.

The is the most advanced form and this family includes the state of the art of Ferrari technology:Piston pumps and load sensing distributorProportional levers or multifunctional joystickFull CAN BUS integrated managementLifting capacity under spreader up to 6 high 8'6''FERRARI EC 08Outstanding forklift truck for empty container handling providing stability and performances at top market level.Lifting capacity under spreader up to 9 tons, stacking up to 8 high + 1Telescopic side spreader 20' 40' single or double liftEC 08 offers its best performances in :- narrow terminals- end on stacking- fork handling- double stackingBeing equipped with special spreaders to safely, neatly and quickly handle empty containers at the terminals, it is developed the new type vehicles focusing on several crucial features-excellent visibility, high-mounted pillar-less cabin, wider view mast, easy and tireless maneuverability, increased operation efficiency and operator friendliness as well.

Rough terrain craneA crane mounted on an undercarriage with four rubber tires that is designed for pick-and-carry operations and for off-road and "rough terrain" applications. Outriggers are used to level and stabilize the crane for hoisting. These telescopic cranes are single-engine machines, with the same engine powering the undercarriage and the crane, similar to a crawler crane. In a rough terrain crane, the engine is usually mounted in the undercarriage rather than in the upper, as with crawler crane.

No matter where you want to build, the Rough Terrain Crane is ready to help with realistic functions! Flip down the outriggers to stabilize the load and extend the powerful telescoping boom! Rotate the base and activate the working controls on the back to lower the winch and raise the payload. Entire crane rotates 360 degrees.

All terrain craneA mobile crane with the necessary equipment to travel at speed on public roads, and on rough terrain at the job site using all-wheel and crab steering. ATs combine the roadability of Truck-mounted Cranes and the manoeuvrability of Rough Terrain Cranes. ATs have 2-9 axles and are designed for lifting loads up to 1200 metric tons.

All Terrain Crane adopts 4-section box type powered telescoping, with all-round hexagonal boom profile, made of high-tensile structural steel, with longitudinal reinforcement for improving partial stability of boom lower plate, better lateral rigidity for boom. 5 sheaves at boom head, the 2nd, 3rd sections and the top one synchronously telescope, telescoping system contains double-action cylinder and wire ropes, and with holding valve fitted in the cylinder. 2-axle chassis with environment engine, all axle drive, all wheel steering and crab walk possible, equipped with advanced hydro-pneumatic suspension and off-road tires, suitable for variable complicated ground conditions. The vehicle can travel on various rough road, operate 360full circle, and also on mid-extended outrigger or on tires, and travel with a suspended load.For example maximum capacity on outriggers 90 t Base machine is as follows:ChassisManufactured by Marchetti, steel torsion-resistant box type construction, width2.75 m.2.76 Outriggers4 hydraulically telescoping beam outriggers. Independent movement controls oneach side of the carrier and in the upper structure cab. Two different outriggerpositions available 6.9 m & 5 m. The outriggers pads are always clasped to thevertical cylinders.

EngineIVECO engine F3A turbo-intercooler EUROMOT 2, 6 cylinder in line, watercooled. Max power 287 kW (385 HP) at 2000 rpm. Max torque 1700 Nm at 1000rpm. Fuel tank capacity 450 liters.

SuspensionAll axles have hydro-pneumatic suspensions. Longitudinal and transverse levelcontrol and locking to allow motion from the upper structure cab. Automaticleveling system for road travel. Cylinder stroke 220 mm.

Electrical system24 V EEC compliant lighting system. N. 1 working light fixed to upper structurecabin.SuperstructureContinuous 360 rotation.

Hoist gearGrooved drum, epicyclical reducer and automatic disk brakes. Axial piston engineand descent control. Rotation indicator. Anti-slewing rope, length 230 m diameter19 mm. Hoisting capacity at the 4th level, 6000 daN.Boom elevationThrough 1 hydraulic double-effect cylinder with safety valve. Boom angle from 1to 82

SlewingPlanetary gear & external sprocket, epicyclical reducer and automatic multipledisk brakes.

Hydraulic systemOne axial pistons load sensing pump for the cranes main circuits; one gearedpump for slewing and for the outriggers; one geared pump for the service circuit.Possibility of activating three contemporary maneuvers. Thermostaticallycontrolled oil cooler for heavy duty jobs.

Crawler crane

A crawler is a crane mounted on an undercarriage with a set of tracks (also called crawlers) that provide stability and mobility. Crawler cranes range in lifting capacity from about 40 US tons to 3500 US tons. Crawler cranes have both advantages and disadvantages depending on their use. Their main advantage is that they can move around on site and perform each lift with little set-up, since the crane is stable on its tracks with no outriggers. In addition, a crawler crane is capable of traveling with a load. The main disadvantage is that they are very heavy, and cannot easily be moved from one job site to another without significant expense. Typically a large crawler must be disassembled and moved by trucks, rail cars or ships to its next location.

Crawler cranes deliver excellent mobility over soft surfaces. These multiple-purpose cranes can be used in a broad range of applications, ranging from construction to civil engineering and port cargo handling.Here are given some specifications of the latest model of a crawler crane for understanding its details: 18-tons (16.3-tonnes) pick-and-carry capacity 360. Pull & pin boom - 70ft (20m) length. Telescopic jib for up to 100ft (30.5m) tip height. 173 hp (129kW) diesel engine standard. Low ground bearing pressure of 5.6 psi (0.39 kg/cm2) or less with counterweight removed. Mantis-engineered auger options with optional hydraulic tool circuit. Two-speed independent hydrostatic track drive to 3 mph (4.8 km/hr). 8ft (2.44m) minimum travel width (with 18ins (457mm) tracks). Extraordinary 7ft 11ns (2.41m) minimum clearance height. Choice of track shoe widths, apex swamp pads or bolt-on rubber track pads to suit any ground surface. 51-54,000lb (23-24.5-tonne) shipping weight fully equipped hauls as a single, ready-to-work load. Steep 70% gradeability thanks to low centre of gravity. Hydraulic on-the-fly track frame retraction and extension. 12,000lb (5.4-tonne) planetary main winch with full load single line speeds to 222 fpm (67.7 mpm). Optional Mantis WP-750 Heavy Duty Work Platform for 82ft (25m) working height.

Railroad crane

A railroad crane has flanged wheels for use on railroads. The simplest form is a crane mounted on a railroad car. More capable devices are purpose-built. Different types of crane are used for maintenance work, recovery operations and freight loading in goods yards. A railroad crane, (crane car or wrecker (US) or breakdown crane (UK)) is a type of crane used on a railroad for one of three primary uses: freight handling in goods yards, permanent way (PW) maintenance, and accident recovery work. Although the design differs according to the type of work, the basic configuration is similar in all cases: a rotating crane body is mounted on a sturdy chassis fitted with flanged wheels. The body supports the jib (UK) (boom (US)) and provides all the lifting and operating mechanisms; on larger cranes, an operator's cabin is usually provided. The chassis is fitted with buffing and coupling gear to allow the crane to be moved by a locomotive, although many are also self-propelled to allow limited movement about a work site.For cranes with a jib that extends beyond the length of the chassis, a match wagon (also known as a 'jib carrier' (UK) or 'boom car' (US)) is provided to protect the jib and to allow the crane to be coupled within a train. The match wagon is usually a long, flat wagon that provides a means of securing the jib for transportation; storage areas for special equipment or supplies are usually fitted too. It was not uncommon for the match wagon to be built on a withdrawn revenue-earning wagon.

Railroad cranes are usually designed specifically for one of three purposes:Goods yard cranesUsually the smallest of the railroad cranes, goods yard cranes were used in the larger goods yards to provide lifting capability in areas away from the ground-mounted goods cranes normally provided in such yards.They were often small enough to be operated by hand, and were not normally self-propelled, instead requiring the use of a shunting engine to move them into position. Once cheap road-going mobile cranes were available, these superseded the rail-mounted variety due to their greater flexibility and mobility.Maintenance cranesThe most varied forms of crane are used for maintenance work. General purpose cranes may be used for installing signalling equipment or pointwork, for example, while more specialised types are used for track laying.Breakdown cranesThe largest cranes are used for accident recovery work, usually forming part of a breakdown train that includes staff accommodation and recovery equipment. These are large enough to lift derailed rolling stock back onto the track, although two or more cranes may be required to safely recover a locomotive. In US terminology, a 'breakdown crane' is often referred to as a 'wrecker'.ConstructionA railroad crane generally resembles a conventional fixed-location crane except that the platform the crane sits on is a heavy-duty reinforced flat car. Directly underneath the center of gravity for the crane is a pivot point that allows the crane to swivel around 360; in this way the crane can locate its boom over the worksite no matter what its location is along the track. The trucks on the car under the crane will often include traction motors so that the crane is able to move itself along the track, and possibly tow additional cars.Larger cranes may be provided with outriggers to provide additional stability when lifting. Sleepers are often carried on the match car to put under the outriggers to spread the weight applied to the trackbed.Breakdown cranes (sometimes called wrecking cranes or 'big hooks) were necessary to every railroad to recover derailed rolling stock and engines; while also assisting with bridge building and yard construction.

Floating crane

Floating cranes are used mainly in bridge building and port construction, but they are also used for occasional loading and unloading of especially heavy or awkward loads on and off ships. Some floating cranes are mounted on a pontoon, others are specialized crane barges with a lifting capacity exceeding 10,000 tons and have been used to transport entire bridge sections. Floating cranes have also been used to salvage sunken ships.Crane vessels are often used in offshore construction. The largest revolving cranes can be found on SSCV Thialf, which has two cranes with a capacity of 7,100 metric tons each.The floating cranes can be used in carrying out high-standard harbour projects, as well as for loading-unloading, transhipping assignments and transportation of heavy loads. Floating cranes made by Gottwald are the ideal choice for cargo handling on waterways with few quays or none at all or if capacities have been exhausted: based on proven Gottwald Mobile Harbour Crane technology for cargo handling independent of quay availability designed for ship-to-ship or ship-to-quay handling.

One Single Idea Many Fields of ApplicationGottwald floating cranes are mobile and can be used: in rivers (mid-stream transhipment) in ports in protected waters in coastal waters on the open seaProven Mobile Harbour Crane Technology on the WaterGottwald Floating Cranes combine Mobile Harbour Crane technology with a barge and can be designed as: Harbour Pontoon Cranes: the crane is on a pedestal mounted on an individually designed barge. Portal Harbour Cranes mounted on a barge: with this special type of crane, the barges have rails upon which the HSK can be travelled thanks to its rail-mounted portal. This enables the crane to service several holds without warping the barge.The numerous variants are developed to meet the requirements of the specific fields of application. Above the slew ring, they have the same components as Gottwald Mobile Harbour Cranes. As a result, this crane type provides all the benefits of the proven Mobile Harbour Cranes, such as: diesel-electric or fully electric drives for optimised efficiency designed to handle all forms of cargo (containers, bulk, general and project cargoes) rapid change of lifting gear.Floating cranes are available in all variants including 4-rope grab variants for professional bulk handling.Aerial crane

Bell 47 helicopters were the first, lightweight aerial cranes to be used in the early 1950s. Unfortunately, due to the helicopter's limited power, it was never capable of carrying more than just a few hundred pounds of cargo. In the 1960s, the Sikorsky S-58 replaced the Bell 47 because of its larger power margin. Even today, S-58s can be found carrying medium-size loads. The 1960s also brought the Bell 211 HueyTug, a specially produced commercial version of the UH-1C for lifting medium loads, and even the popular Bell 206 was used for light loads. But there continued to be a demand for aircraft able to lift even larger loads. Aerial crane or 'Sky cranes' usually are helicopters designed to lift large loads. Helicopters are able to travel to and lift in areas that are difficult to reach by conventional cranes. Helicopter cranes are most commonly used to lift units/loads onto shopping centers and highrises. They can lift anything within their lifting capacity, (cars, boats, swimming pools, etc.). They also perform disaster relief after natural disasters for clean-up, and during wild-fires they are able to carry huge buckets of water to extinguish fires. Some aerial cranes, mostly concepts, have also used lighter-than air aircraft, such as airships.

So Helicopters used to lift heavy loads are called aerial cranes or skycranes. As aerial cranes, helicopters carry loads connected to long cables or slings in order to place heavy equipment when other methods are not available or economically feasible, or when the job must be accomplished in remote or inaccessible areas, such as the tops of tall buildings or the top of a hill or mountain, far from the nearest road. Helicopters were first used as aerial cranes in the 1950s, but it was not until the 1960s that the popularity of the use of skycranes in the construction and other industries began to catch on. The most consistent use of helicopters as aerial cranes is in the logging industry to lift large trees out of rugged terrain where vehicles aren't able to reach, or where environmental concerns prohibit the buildings of roads.These operations are referred to as longline because of the long, single sling line used to carry the load.

Disadvantages and accidents

Overload preventersThe main principles concerned are:1. Overload preventers with strain gauges or load cells.2. Overload preventers with load measuring pins.

Overload preventers with strain gaugesThe strain gauges or load cells can be built-in directly behind a deadendof a hoisting wire rope or in a yoke which is carrying wire ropesheaves, or underneath a gear-box. Usually the crane driver can checkthe approximate weight of the carried load on a display in his cabin.

Overload preventers with load measuring pinsHigh quality stainless steel load pins contain strain gauges which aremounted in a particular way which give a load proportional signal. Theload measuring pins can be built-in in a wire rope sheave or in the pinof a hydraulic cylinder. Load monitoring can also be done in the cranedrivers cabin etc.

Anti-collision systemsSome anti-collision systems work using the principles of: sonar; radar; low frequency near-field induction.Miscellaneous 287

SonarAlthough the principle is very good, there is the danger with this systemthat a strong wind can blow the sonar waves away.

RadarRadar usually uses advanced microwave or Doppler radar technologycombined with some digital signal processing. Safety circuits are builtin,and the system can sense objects up to a distance of about 40 m.The maximum crane travel speed is about 200 m_min.The radar beam which is sent out will be reflected by solid objectsand will be received by the same radar antenna. It can measure thedistance between two objects and also the speed with which the objectis approaching the sensed object.

Low-frequency near-field induction systemThese low frequency systems work at a frequency of approximately 90to 220 kHz and have a working maximum range of about 30 m. Atransmitter and antenna is installed on the first crane and a receiver andantenna on the adjacent crane. With this system it is possible to installthree distance steps between the cranes, which should be respected. Forexample: at 30 m distance an audible signal is given; at 20 m distance the crane speed is decreased; at 5 m distance the final stop signal is given.

Maintenance

GeneralWith a well made piece of equipment, maintenance becomes a majorfactor to keep this machinery in good condition. An organization withreliable maintenance engineers should be formed to do this importantjob. Discipline is needed to carry out regular inspections at the righttime and with the necessary care and attention.For rolling equipment like straddle carriers and AGVs (AutomatedGuided Vehicles), a well equipped workshop will be the best place toconcentrate all important maintenance jobs.Moveable platforms which can surround the taller equipment suchas straddle carriers can be useful, as can moveable grease guns withlong, flexible grease hoses and moveable drain containers. Special crickscan help to change heavy tyres rapidly and easily.The extensive maintenance manuals normally give enough informationabout the frequency of inspection and the items which are to bechecked and maintained. The same principles apply to mobile craneswhich are able to move around freely. However, as they are normallytoo large to be worked on inside a workshop, the maintenance must becarried out in situ or in a predetermined maintenance position at theterminal or quay. Refuelling of the diesel engines also needs to beorganized with precision.For cranes running on rails, such as the many types of ship-unloadingand loading equipment, stacking cranes, etc. the maintenance workmust be carried out in situ. The complete systems and the automationrequire specialist skills. The training of a suitable team of operatives is310 Cranes Design, Practice, and Maintenanceexpensive and time consuming, but absolutely necessary. Inspection andmaintenance of the hydraulic equipment similarly demands specialistknowledge and a sound understanding of the systems which are in use.Mechanical engineers must inspect the wire ropes and wire rope systems,hoist-, travel-, luff- and slew mechanisms, brakes, gearboxes, anddrums. Steel structures also require checking for fatigue cracking andother faults. Bolts should be checked regularly for signs of loosening,corrosion, cracking or other damage. Greasing and lubrication are animportant part of this whole process because while this essential procedureis being undertaken, the engineers can carry out visual, mechanicaland other testing at the same time. Greasing and lubrication needto be thorough and not skimped on even though it is both costly andmessy. It is one of the most important ways in which the useful lifeof equipment can be extended and the downtime through repair andbreakdown reduced.Railtracks should be inspected from time to time, especially thosetracks which are laid on sleepers and ballast beds. Allowable deviation of the span if span15 m, G3mmif span.15 m, Gto10mm increasing Allowable deviation of one railfrom the nominal straight line inthe horizontal plane max 1:1000 Allowable deviation of one railfrom the nominal straight line in local 1:1000; over the fullthe vertical plane length of the track 1:5000CAUTION: During crane operations, do not enter a crane cab without the knowledge and expressed consent of the operator. Conduct of OperatorsMobile crane operations can be complex and subject to hazards beyond those experienced with fixed equipment. Mobile crane operators require applicable experience and must exercise intelligence, care, and common sense in addition to knowing the following rules: Do not engage in any attention-diverting activity while operating the crane. When physically or mentally unfit, do not engage in the operation of equipment. Respond to signals from the appointed signal person. Obey a stop signal no matter who gives it. (See Hand Signals.) Operators are responsible for those operations under their direct control. Whenever there is any doubt as to safety, consult with the supervisor before handling the loads.

Before leaving the crane unattended, perform the following tasks: land any load, bucket, lifting magnet, or other device disengage the master clutch set travel, swing, boom brakes, and other locking devices put controls in the off or neutral position secure the crane against accidental travel stop the engine. An exception to stopping the engine may exist when crane operation is frequently interrupted during a shift and the operator must leave the crane. Under these circumstances, the engine may remain running and the following conditions, including the previous bulleted items above, shall apply: crane is situated where unauthorized entry of the crane can be observed crane is located within an area protected from unauthorized entry. When a local weather storm warning exists, follow the recommendations of the manufacturer for securing the crane.If there is a warning sign on the switch or engine starting controls, do not close the switch or start the engine until the warning sign has been removed by the person who placed it or an appointed person. Before starting the crane, see that all controls are in the off or neutral position and that all personnel are in the clear. If power fails during operations: set all brakes and locking devices move all clutches or power controls to the neutral position if practical, land the suspended load under brake control. Be familiar with the equipment and its proper care. If adjustments or repairs are necessary, promptly report this to the appointed person and notify the next operator. Test all controls at the start of a new shift. If any controls fail to operate properly, they require adjustment or repair before operations begin. Follow the manufacturer's boom assembly and disassembly procedures. Any deviation from the manufacturer's procedure shall require blocking of the boom or boom sections to prevent inadvertent dropping of the boom. When removing pins or bolts from a boom, workers should stay out from under the boom. Each outrigger shall be visible to the operator or to a signaler during extension or setting.Operating PracticesSwing RadiusPinch Point Clearance When the crane is in operation, maintain a minimum clearance of 30 inches (76 centimeters) between the swing radius of the crane superstructure or counterweights and any stationary object. When this clearance cannot be maintained, isolate pinch point hazards with barricades or safeguards. Where possible, flag or barricade the swing radius. Handling the Load Load no crane beyond the specifications of the load rating chart, except for test purposes. CAUTION: Total load always includes the lifted item and the rigging. Additionally, the crane hook, block, and load line may also be considered part of the load. Attachments to the boom such as a jib or auxiliary whip lines affect crane stability and may be considered part of the load. Consult the manufacturers operating manual for direction. When the precise load weight is not known, the person responsible for the lift shall ascertain that the weight does not exceed the crane rating at the radius at which the load is to be lifted. CAUTION: If a load of unknown weight is potentially near the cranes capacity, a load-indicating device should be used. If a load must "break-loose" before lifting, or while being handled, or if it may meet an obstruction, a load-indicating device should be used. If a lift is potentially limited by structural competence of the crane, rather than by stability, the load shall be determined within plus or minus 10% before it is lifted. Use regular lay wire rope for crane load lines with an operating design factor of no less than 3.5. Load lines with rotation-resistant ropes require an operating design factor of no less than 5. Note: Standard ASME B30.5-3.2.1 grants special provisions for the use of rotation-resistant ropes with an operating design factor less than 5, but no less than 3.5. These provisions are not intended for duty cycle of repetitive lifts. The crane manufacturer shall be consulted and strict compliance with ASME B30.5 is required if such special provisions are implemented. Attaching the Load Perform the following tasks when attaching the load: Never wrap the hoist rope around the load. Attach the load to the hook by means of slings or other devices of sufficient capacity. If the crane is not equipped with automatic drum and boom braking systems and the load is to remain suspended for any considerable length of time, set the drum and boom brakes to hold the load.

Holding the Load Do not leave the controls while the load is suspended. As an exception to the direction above, when a load is to be held suspended for a period exceeding normal lifting operations, the operator may leave the controls provided: The supervisor and the operator establish requirements for restraining the boom hoist, telescoping, load, swing, and outrigger functions. Barricades, or whatever other precautions may be necessary, are taken. No person should be permitted to stand or pass under a suspended load.

Moving the Load CAUTION: Ground- and Bearing-Pressure Considerations. It is important to ensure that no underground installations exist that could be compromised, such as electrical vaults, conduit banks, tanks, and piping. When crane load foundations and bearing pressure are a concern to crane stability and underground installation integrity, site utility layout, crane manufacturers ground-loading information, crane configuration, and load and travel path information shall be evaluated and analyzed by a qualified person. The qualified person shall determine if ground scans, soil stability tests, and structural analysis of underground structures is necessary. If analysis is performed, a documented plan to ensure crane stability and integrity of underground installations shall be provided to the supervisor of the lift operation and discussed with involved or affected personnel.Preconditions. The person directing the lift (supervisor or designated leader) shall ensure: crane is level and, where necessary, blocked load is well secured and balanced in the sling or lifting device before it is lifted more than a few inches lift and swing path is clear of obstructions all persons are clear of the swing radius of the crane counterweight.Before Starting the Lift. Before starting the lift, the operator shall ensure: hoist rope is not kinked multiple-part lines are not twisted around each other hook is over the load in such a manner as to minimize swinging if there is a slack rope condition, the rope is seated on the drum and in the sheaves as the slack is removed wind speed and other weather conditions shall be considered. Do not attempt lifts if weather conditions are adverse to safe load-handling operations. load line is plumb so the cranes will not drag the load sideways. During Lifting Operations. During lifting operations, care shall be taken to ensure: no sudden acceleration or deceleration of the moving load. load, boom, or other parts of the machine do not contact any obstructions or enter the Danger Zone around electrical transmission lines (see Operating Cranes Near Energized Transmitters or Electric Power Lines) or a transmitter tower (see Operating Near a Transmitter Tower).CAUTION: When landing loads on blocking, the loads must be set on adequate blocking to prevent damage to the slings and the loads must be safely landed and properly blocked to avoid unexpected roll over or tipping before being unhooked and unslung. Side Loading. Side loading of booms shall be limited to freely suspended loads. Do not drag loads sideways. Avoid Loads Over People. The operator should avoid carrying loads over people. Wheel-Mounted Cranes - Lifting Over Front. On wheel-mounted cranes, do not lift over the front area, except as specified by the manufacturer. CAUTION: Working on or under a suspended load is prohibited, except when the load can be supported by blocking or cribbing, can be securely braced, or can be supported substantially by some other means that would prevent the load from moving. Loads being lifted and set in place may require special handling control measures that may require personnel to position their hands or other body parts under the load when inspecting, landing, setting, or controlling the load. To ensure that appropriate controls are implemented to control unwanted movement of the load, issues concerning "hands-on" work under suspended loads, guiding or controlling suspended loads, and fine load control shall be discussed and resolved during pre-lift planning. Brake Test - When Load Approaching Rated Load. Whenever a load approaching the rated load is handled, the operator shall test the brakes by lifting the load a few inches and applying the brakes. Outriggers. Anytime the load or radius requires the use of outriggers, fully extend or deploy them per the load rating chart specifications. Outriggers are set to remove the machine weight from wheels. When outrigger floats are used, they shall be attached to the outriggers. Blocking under outrigger floats, shall meet the following conditions: Have sufficient strength to prevent crushing, bending, or shear failure. Be of adequate size and thickness to completely support the float, transmit the load to the supporting surface, and prevent shifting, toppling, or excessive settlement under load. Use blocking only under the bearing surface of the outrigger. Minimum Two Wraps on Drums. Neither the load nor the boom shall be lowered below the point where less than two full wraps of rope remain on the respective drums. Lifts with Two or More Cranes. When two or more cranes are used to lift a load, a designated person shall direct the lifting operation. That person analyzes the operation and instructs involved personnel in the proper crane positioning, rigging, and the movements that will be accomplished. Decisions, such as the necessity to reduce crane ratings, load position, boom location, ground support, and speed of movement shall be made. A pre-lift meeting shall be held by the designated person with the crane operators and other involved personnel in attendance. The plan/procedure shall be reviewed and questions shall be resolved.

Moving Cranes From One Job Site to Another (Transit). Prepare the crane for transit in accordance with the manufacturer's instructions. (See Lattice Boom Dismantling/Assembly concerning lattice boom dismantling/assembly.) The following additional precautions shall be exercised while the crane is in transit from job to job: Carry the boom in line with the direction of motion. Secure the superstructure against rotation (or place the boom in a boom rack mounted on the carrier), except when negotiating turns when there is an operator in the cab or the boom is supported on a dolly. Lash down or otherwise secure empty hook(s) to restrain them from swinging freely. If questions arise about this provision, the manufacturer's instructions shall govern.Notes: 1) When the machine moves under its own power from one location to another on a job site, the supervisor and/or crane operator shall determine the machine's condition for travel. 2) See Definitions and Acronyms, Travel, and Transit.Traveling with a Load. Traveling with suspended loads entails many variables (i.e., the type of terrain, boom length, momentum in starting and stopping, etc.) Therefore, it is impossible to formulate a single standard procedure with any assurance of safety. Thus, while traveling with a load, a designated person, in coordination with the crane operator, must evaluate prevailing conditions and determine applicable safety precautions. Before a crane travels with a load, determine that the manufacturer does not prohibit this practice. If the manufacturer has approved traveling with a load, a designated person shall be responsible for the operations. Decisions such as the necessity to reduce crane ratings, load position, boom location, ground support, travel route, speed of movement, and outrigger position shall be in accordance with that persons determination and the manufacturers instructions. No person shall ride on the machine during "pick-and-carry" operations. Unless allowed by the manufacturers operating instructions or written approval from the manufacturer, do not place the load on any part of the crane. Check the specified tire pressure and travel with the boom in line with the direction of travel. Avoid sudden starts and stops. Use tag or restraint lines as necessary to control swinging of the load. CAUTION: The travel path should be smooth, firm, and level. If soil stability is questionable, soil tests may be necessary to determine stability. Where potential underground hazards exist (such as electrical vaults, conduit banks, tanks, and piping), they must be evaluated and action must be taken to make sure mobile crane operations can be accomplished safely. A crane with or without a load must not travel with the boom so high that it may bounce back over the cab. During "pick-and-carry" operations, exercise extra caution to avoid electrical hazards from working near energized transmitters or power lines (see Operating Cranes Near Energized Transmitters or Electric Power Lines).During "pick-and-carry" operations, always use a minimum of two signal persons to assist the crane operator; one signal person will serve as the flagger with key responsibility for watching the load and signaling as necessary to control load movement. The second signal person will have the key responsibility to watch for and signal as necessary to avoid hazards involving the crane's movement. Typical obstructions and hang-ups include power lines and any other obstructions for which the crane operator may not have a clear line of sight

. Rotational Speed. When the crane is rotated, avoid sudden starts and stops. Limit the rotational speed such that the load does not swing out beyond the radius at which it can be controlled. Use tag or restraint lines as necessary to control the load. Boom at Fixed Angle. When a crane is to be operated with the boom at a fixed angle, the boom-hoist pawl or other positive holding device shall be engaged. Use of Winch Heads. A winch head shall not be used without the knowledge of the operator. While a winch head is being used, the operator shall be within convenient reach of the power unit control lever. Riding Hook or LoadNot Permitted. Personnel are not permitted to ride the bare hook, hook ball or a suspended load. (For personnel lifting, see Lifting of Personnel.) Footing. A firm footing under both crawler tracks, all tires, or individual outrigger pads should be provided. Where such a footing does not exist, timbers, cribbing, or other structural members shall be provided to distribute the load. Do not exceed the bearing capacity of the underlying material. (See Caution: Ground-and Bearing-Pressure Considerations above.) The crane must be level within tolerances and in accordance with the instructions from the manufacturer. Ballast or Counterweight. Ensure ballast or counterweight is in place as specified by the crane manufacturer. The addition of ballast or counterweight other than that specified by the crane manufacturer is dangerous and not allowed. Personnel Lifting. (See Lifting of Personnel.) Contact the PNWD Hoisting and Rigging subject matter expert. Operating Cranes Near Energized Transmitters or Electric Power Lines. It is recognized that operating mobile cranes where they can become electrified from electric power lines and transmitter towers is an extremely hazardous practice. It is advisable to perform the work so there is no possibility of the crane, load line, or load becoming a conductive path. Note: A sign warning of electrocution hazards is required on cranes, see Signs.Operating Near a Transmitter Tower. Before initiating work near a transmitter tower (e.g