Rabu, 16 Januari 2008

Types of Cranes

Types of cranes

Railroad cranes

Diesel-powered railroad crane for maintenance work – Tampa, Florida.
Diesel-powered railroad crane for maintenance work – Tampa, Florida.
Brute 125 ton hirail crane – BNSF Springfield, Missouri Railyard.
Brute 125 ton hirail crane – BNSF Springfield, Missouri Railyard.
Main article: Crane (railroad)

A railroad crane is a crane with flanged wheels, used by railroads. The simplest form is just a crane mounted on a railroad car or on a flatcar. More capable devices are purpose-built.

Different types of crane are used for maintenenace work, recovery operations and freight loading in goods yards.

Mobile crane

The most basic type of mobile crane consists of a steel truss or telescopic boom mounted on a mobile platform, which may be rail, wheeled (including "truck" carriers) or caterpillar tracks. The boom is hinged at the bottom, and can be raised and lowered by cables or by hydraulic cylinders. A hook is suspended from the top of the boom by wire rope and sheaves. The wire ropes are operated by whatever prime movers the designers have available, operating through a variety of transmissions. Steam engines, electric motors and internal combustion engines (IC) have all been used. Older cranes' transmissions tended to be clutches. This was later modified when using IC engines to match the steam engines "max torque at zero speed" characteristic by the addition of a hydrokinetic element culminating in controlled torque converters. The operational advantages of this arrangement can now be achieved by electronic control of hydrostatic drives, which for size and other considerations is becoming standard. Some examples of this type of crane can be converted to a demolition crane by adding a demolition ball, or to an earthmover by adding a clamshell bucket or a dragline and scoop, although design details can limit their effectiveness.

To increase the horizontal reach of the hoist, the boom may be extended by adding a jib to the top. The jib can be fixed or, in more complex cranes, luffing (that is, able to be raised and lowered).

A telescopic crane dismantling a 40 m tower crane in Cambridge, UK
A telescopic crane dismantling a 40 m tower crane in Cambridge, UK

Telescopic crane

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.

Tower crane

Six tower cranes constructing buildings at Canon's Marsh, Bristol, England.
Six tower cranes constructing buildings at Canon's Marsh, Bristol, England.
Luffing tower crane,Singapore
Luffing tower crane,Singapore
Concrete counter-weights on a tower crane Cape Town, South Africa.
Concrete counter-weights on a tower crane Cape Town, South Africa.
A "jack up" mast supporting a tower crane. The inner element is moved upward with jacks and a new outer section is assembled around the exposed portion.
A "jack up" mast supporting a tower crane. The inner element is moved upward with jacks and a new outer section is assembled around the exposed portion.

The tower crane is a modern form of balance crane. Fixed to the ground (or "jacked up" and supported by the structure as the structure is being built), tower cranes often give the best combination of height and lifting capacity and are used in the construction of tall buildings. To save space and to provide stability the vertical part of the crane is often braced onto the completed structure which is normally the concrete lift shaft in the center of the building. A horizontal boom is balanced asymmetrically across the top of the tower. Its short arm carries a counterweight of concrete blocks, and its long arm carries the lifting gear. 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, usually standing near the load. In the first case the operator's cabin is located at the top of the tower just below the horizontal boom. The boom is mounted on a slewing bearing and is rotated by means of a slewing motor. The lifting hook is operated by a system of sheaves.

A tower crane is usually assembled by a telescopic crane of smaller lifting capacity but greater height and in the case of tower cranes that have risen while constructing very tall skyscrapers, a smaller crane (or derrick) will sometimes be lifted to the roof of the completed tower to dismantle the tower crane afterwards. A self-assembling tower crane lifts itself off the ground using jacks, allowing the next section of the tower to be inserted at ground level. It is often claimed that a large fraction of the tower cranes in the world are in use in Dubai. The exact percentage remains an open question. [1]

Hammerhead crane

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. Hammerhead cranes are generally constructed in large sizes, up to 350 tons.

The design evolved first in Germany around the turn of the 19th century and was adopted 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. Hammerhead cranes were also installed in naval shipyards in Japan and in the USA. The British Government also installed a hammerhead 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 hammerhead cranes in the British empire was Sir William Arrol & Co Ltd.

Truck-mounted crane

A typical truck-mounted crane
A typical truck-mounted crane

A crane mounted on a truck carrier provides the mobility for this type of crane.

Generally, these cranes are designed to be able to travel on streets and highways, eliminating the need for special equipment to transport a crane to the jobsite. When working on the jobsite, outriggers are extended horizontally from the chassis then down vertically to level and stabilize the crane while stationary and hoisting. Many truck cranes possess limited slow-travelling capability (just 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 of the anti-tipping stability then lies in the strength and stiffness of the chassis suspension. Most cranes of this type also have moving counterweights for stabilization beyond that of the outriggers. Loads suspended directly over the rear remain more stable, as most of the weight of the truck crane itself then acts as a counterweight to the load. Factory-calculated charts (or electronic safeguards) are used by the crane operator to determine the maximum safe loads for stationary (outriggered) work as well as (on-rubber) loads and travelling speeds.

Truck cranes range in size from about 14.5 US Tons to about 600 US tons.

Rough terrain crane

Omega 18 ton rough terrain crane manufactured by P & H.
Omega 18 ton rough terrain crane manufactured by P & H.

A 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 that extend horizontally and vertically are used to level and stabilize the crane for hoisting.

These telescopic cranes are single-engine machines where the same engine is used for powering the undercarriage as is used for powering the crane, similar to a crawler crane. However, in a rough terrain crane, the engine is usually mounted in the undercarriage rather than in the upper, like the crawler crane.

Crawler crane

A crawler is a crane mounted on an undercarriage with a set of tracks that provide for the stability and mobility of the crane. Crawler cranes have both advantages and disadvantages depending on their intended use. The main advantage of a crawler is that they can move on site and perform lifts with very little set-up, as 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 of a crawler crane is that they are very heavy, and cannot easily be moved from one job site to the next without significant expense. Typically, a large crawler must be disassembled and moved by trucks, rail cars or ships to be transported to its next location.

Gantry crane

Portainer gantry cranes at the Hamburg Harbour
Portainer gantry cranes at the Hamburg Harbour

A gantry crane has a hoist in a trolley which runs horizontally along gantry rails, usually fitted underneath a beam spanning between uprights which themselves have wheels so that the whole crane can move at right angles to the direction of the gantry rails. 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 after the first manufacturer), designed for loading and unloading ship-borne containers at a port.

Overhead crane

Also known as a "suspended crane", this type of crane works in the same way as a gantry crane but without uprights. The hoist is on a trolley which moves in one direction along one or two beams, which move at right angles to that direction along elevated tracks, often mounted along the side walls of an assembly area in a factory. Some of them can lift very heavy loads.

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.

Uglen is another, smaller crane vessel.

Vessel (Deck) crane

Located on the ships and used for cargo operations which allows to reduce costs by avoiding usage of the shore cranes. Also vital in small seaports where no shore cranes available. Mostly are electric, hydraulic, electro-hydraulic driven.

Aerial crane

Aerial cranes usually extend from helicopters to lift large loads. Helicopters are able to travel to and lift in areas that are more difficult to reach by a conventional crane. Aerial helicopter cranes are most commonly used to lift units/loads onto shopping centers, multi-story buildings, highrises, etc. However, they can lift basically anything within their lifting capacity, (i.e. cars, boats, swimming pools, etc.). They also work as disaster relief after natural disasters for clean-up, and during wild-fires they are able to carry huge buckets of water over fires to put them out.

Examples include:

Jib crane

Pedestal Crane, a type of jib crane.
Pedestal Crane, a type of jib crane.


A 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.

Crane-like machines

The generally-accepted definition of a crane is a machine for lifting and moving heavy objects by means of ropes or cables suspended from a movable arm. As such, a lifting machine that does not use cables, or else provides only vertical and not horizontal movement, cannot strictly be called a 'crane'.

Types of crane-like lifting machine include:

More technically-advanced types of such lifting machines are often known as 'cranes', regardless of the official definition of the term. Some notable examples follow:

Loader crane

A loader crane offloading aerated concrete bricks at a building site
A loader crane offloading aerated concrete bricks at a building site

A loader crane (also called a knuckle-boom 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.

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, 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.

Rolloader crane

This 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.

Manufacturer of rolloader cranes include the Dutch Kennis [2] and the Finnish company Hiab (Hydrauliska Industri AB)....

Stacker crane

A 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.

Sidelift

A sidelift is a road going truck or semi-trailer that is used to hoist and transport ISO standard containers. Lifitng of containers is achieved through the use of parallel crane like hoists, which can be used to lift a container from the ground, or from a railway vehicle.

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