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A derrick is a
lifting device Lifting equipment, also known as lifting gear, is a general term for any equipment that can be used to lift and lower loads. Types of lifting equipment include heavy machinery such as the patient lift, overhead cranes, forklifts, jacks, building ...
composed at minimum of one
guyed mast A guyed mast or guyed tower is a tall thin vertical structure that depends on guy lines (diagonal tensioned cables attached to the ground) for stability. The mast itself has the compressive strength to support its own weight, but does not ha ...
, as in a
gin pole A gin pole is a supported pole that uses a pulley or block and tackle on its upper end to lift loads. The lower end is braced or set in a shallow hole and positioned so the upper end lies above the object to be lifted. The pole (also known as a ...
, which may be articulated over a load by adjusting its guys. Most derricks have at least two components, either a guyed mast or self-supporting
tower A tower is a tall Nonbuilding structure, structure, taller than it is wide, often by a significant factor. Towers are distinguished from guyed mast, masts by their lack of guy-wires and are therefore, along with tall buildings, self-supporting ...
, and a boom hinged at its base to provide articulation, as in a ''stiffleg'' derrick. The most basic type of derrick is controlled by three or four lines connected to the top of the mast, which allow it both to move laterally and cant up and down. To lift a load, a separate line runs up and over the mast with a hook on its free end, as with a crane. Forms of derricks are commonly found aboard ships and at docking facilities. Some large derricks are mounted on dedicated
vessels Vessel(s) or The Vessel may refer to: Biology *Blood vessel, a part of the circulatory system and function to transport blood throughout the body *Lymphatic vessel, a thin walled, valved structure that carries lymph *Vessel element, a narrow wat ...
, and known as floating derricks and
sheerleg A floating sheerleg (also: shearleg) is a floating water vessel with a crane built on shear legs. Unlike other types of crane vessel, it is not capable of rotating its crane independently of its hull. There is a huge variety in sheerleg capaci ...
s. The term derrick is also applied to the framework supporting a drilling apparatus in an
oil rig {{about, , the mnemonic OIL RIG, Redox An oil rig is any kind of apparatus constructed for oil drilling. Kinds of oil rig include: * Drilling rig, an apparatus for on-land oil drilling * Drillship, a floating apparatus for offshore oil drilling * ...
. The derrick derives its name from a type of
gallows A gallows (or scaffold) is a frame or elevated beam, typically wooden, from which objects can be suspended (i.e., hung) or "weighed". Gallows were thus widely used to suspend public weighing scales for large and heavy objects such as sacks ...
named after
Thomas Derrick Thomas Derrick was an English executioner ''c.'' 1608.A Classical Dictionary of the Vulgar Tongue, Francis Grose In English history, executioner was not a commonly chosen career path because of the risk of friends and families of the deceased kno ...
, an
Elizabethan era The Elizabethan era is the epoch in the Tudor period of the history of England during the reign of Queen Elizabeth I (1558–1603). Historians often depict it as the golden age in English history. The symbol of Britannia (a female personifi ...
English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...
executioner An executioner, also known as a hangman or headsman, is an official who executes a sentence of capital punishment on a legally condemned person. Scope and job The executioner was usually presented with a warrant authorising or order ...
.


Types

polygon In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed ''polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the two toge ...
. There are crossbars between the pole members to strengthen their support. The supporting ropes are tied to the top of the basket poles on one end and joined together on the other end at a lower elevation than the top of the basket poles to form the base for the derrick tower. The derrick tower can be a mast or a post with the bottom hinged at the base where all ropes meet. The top of the tower is secured with multiple reeved guys to position the top of the tower to the desired location by varying the length of the upper guy lines. The load is lifted using a pulley system connected to the top of the tower.


Breast

A breast derrick is a derrick without a boom with a mast constructed from two upright members. The upright members are more spread at their bottom ends than their top ends. There are crossbars to join the two members from the bottom to the top to form a mast..


Chicago boom

A Chicago boom derrick is a derrick with a boom which is attached to an external structure. The external upright member of the structure serves as the mast, and the boom is stepped in a fixed socket clamped to the upright. The boom is connected to at least three pulley systems to control the position of the boom. For example, a pulley system is connected to the top of the boom and the higher area of the external structure and two pulley systems near the top of the boom connected on either side of the boom to the external structure. The position of the top of the boom can be controlled by manipulating these pulley systems. The load is lifted from a separate pulley system that is connected to the top of the boom.


Gin pole

Gin pole derrick (also known as standing derrick or pole derrick) is a derrick without a boom with single tower or mast supported by 4 guy wires (two side guys, fore guy and rear guy). Its guys are so arranged from its top as to permit leaning the mast in any direction. The base of the tower is hinged and the top of the tower is connected to a pulley system for load lifting. As this is a simple derrick system, it is considered to be used by some agencies as an improvised rescue derrick in an emergency situation where no suitable rescue derrick or crane is available.


Guy

Guy derrick (also known as boom derrick) is a fixed guyed mast derrick that can be rotated and connected to a boom. The mast is in upright position with the base that can make the mast rotate, but not to be lean in any direction. The top of the mast is connected to many guy wires which are anchored to the ground to support the load. At the base, the mast is also connect to the bottom end of the boom. The boom extends outward and upward to the desired position. The top of the boom is a pulley system that is connected to the top of the mast to control how far the boom is to be from the mast. When the mast is rotated, the connected boom is swung from to the side. The control of the lifting location is done by the manipulation of the top pulley system and the rotation of the mast at the base. The load is lifted by another pulley system connected to the top of the boom. In a medium load lifting, another construction method can be used. In this case, the mast is fixed without being rotated, but the boom can be swung around the mast. This can be done by connecting the bottom of the boom with two boards on the opposite sides around the surface of the boom to form a fork. The fork and the bottom part of the boom is lashed to secure them together. Another lashing is between the fork area and the mast at a higher position to support the weight of the boom. The fork is put around the mast such that the bottom of the boom is rested on the mast without permanently fixed to it. The fork prevent the boom to come off the mast while swinging up to 180 degrees.


Shearleg

Shearleg derrick is similar to breast with an exception that instead of fixed guy wires that secure the top of the mast, it is secured by multiple reeved guy to permit handling loads at various radii by means of load tackle pulley system suspended from the mast top. In a simpler construction, a shearleg derrick can be assembled from two posts to form A-frame shear legs without any crossbar. The bottom of the legs are set in two holes on the ground spreading them apart. There is a rope to tie the two legs together near the bottom to prevent them from spreading apart further. On the top side, the two legs are connected together by a
lashing Lash or Lashing may refer to: * Eyelash * Whiplash (disambiguation) * Lashing (ropework), a form of connecting solid objects tightly using rope or cord * Flagellation, a form of torture or punishment involving a whip * Backlash (engineering), cle ...
but with a small spacer block placed between the legs. A sling, which may be made from ropes, is placed around the area that two legs meet to be used to put a tackle pulley system for lifting the load. There are two guy wires, front and rear, to support the shear legs. The rear guy may be reeved to allow adjustment of the angle of the shear legs.


Stiffleg

The Stiffleg derrick, also known as a Scotch derrick, is a derrick with a boom similar to a guy derrick, but instead of using guy wires to secure the top of the mast, it uses two or more stiff members, called stifflegs, which are capable of resisting either
tensile In physics, tension is described as the pulling force transmitted axially by the means of a string, a rope, chain, or similar object, or by each end of a rod, truss member, or similar three-dimensional object; tension might also be described as t ...
or
compressive forces In mechanics, compression is the application of balanced inward ("pushing") forces to different points on a material or structure, that is, forces with no net sum or torque directed so as to reduce its size in one or more directions.Ferdinand P ...
. Sills may also be used to connect between the bottom ends of the stifflegs and the base of the mast. There may be a
counterweight A counterweight is a weight that, by applying an opposite force, provides balance and stability of a mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves energy and causes less wear ...
to place on the sills behind the stifflegs in heavy load lifting. Stiffleg derrick on a vessel is called a floating stiffleg derrick. Derricks are especially useful for high rise rigging, jobs that cover a long period of time, or jobs when the impact to the street/pedestrian traffic is a concern. File:Budco Stiffleg Derrick.jpg, Stiffleg derrick performing high rise rigging on a rooftop


Oil derrick

Another kind of derrick is used on
oil well An oil well is a drillhole boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas may ...
s and other drilled holes. Both the structure itself and the complex set of machines associated with it are referred to as a Derrick. This is also used on some offshore oil and gas rigs.


Patent systems


Hallen

The
boom Boom may refer to: Objects * Boom (containment), a temporary floating barrier used to contain an oil spill * Boom (navigational barrier), an obstacle used to control or block marine navigation * Boom (sailing), a sailboat part * Boom (windsurfi ...
is connected with the lower part of the
mast Mast, MAST or MASt may refer to: Engineering * Mast (sailing), a vertical spar on a sailing ship * Flagmast, a pole for flying a flag * Guyed mast, a structure supported by guy-wires * Mooring mast, a structure for docking an airship * Radio mast ...
which is shaped like a "Y" or a
bipod A bipod is a V-shaped portable attachment that helps support and steady a device, usually a weapon such as a long gun or a mortar. The term comes from the Latin prefix ''bi-'' and Greek root ''pod'', meaning "two" and "foot" respectively. Bipod ...
and therefore it is a single swinging derrick. On the cross trees, two guys are fastened using
swivel A swivel is a connection that allows the connected object, such as a gun, chair, swivel caster, or an anchor rode to rotate horizontally or vertically. Swivel designs A common design for a swivel is a cylindrical rod that can turn freely wi ...
outriggers which are stayed vertically and horizontally. In order to maintain a good controlling angle between guys and derrick, the outriggers cannot pass the inboard parallel of the centerline. Looking at the illustration, one can easily see that the right outrigger stays in the centerline and the left outrigger has moved outboard. This derrick will lower or heave cargo as both guys are veered or hauled. Three winches, controlled by joystick, are necessary to operate the Hallen Derrick; two for the guys and one for the purchase. To avoid an over-topping or over-swinging limit-switches are used. However, the limits can be modified if a different working range or a special vertical stowage is required. The
safe working load Safe Working Load (SWL) sometimes stated as the Normal Working Load (NWL) is the maximum safe force that a piece of lifting equipment, lifting device or accessory can exert to lift, suspend, or lower, a given mass without fear of breaking. Usually ...
(SWL) of the Hallen is between 10 and 80 tonnes. In a Hallen Universal derrick, which has no Hallen D-Frame, the
halyard In sailing, a halyard or halliard is a line (rope) that is used to hoist a ladder, sail, flag or yard. The term ''halyard'' comes from the phrase "to haul yards". Halyards, like most other parts of the running rigging, were classically made of n ...
has an extended length since it runs through further blocks on the centerline. The Universal Hallen derrick, replacing the D-frame option, is a kind of traditional topping lift. The Hallen D-Frame is a steel bracket welded on the mast in the centerline. For an observer standing a
beam Beam may refer to: Streams of particles or energy *Light beam, or beam of light, a directional projection of light energy **Laser beam *Particle beam, a stream of charged or neutral particles **Charged particle beam, a spatially localized grou ...
, the frame has a "D"-shape. The D-Frame supersedes the outriggers and provides a good controlling angle on the guys. The Hallen derrick has a good purpose for e.g. containers, logs, steel rail, sawn timber and heavy lifts and doesn't lend itself for small, general cargo. It keeps the deck clear of guy ropes and preventors. Only one winchman is needed and within a few minutes the Hallen is brought into use. It is less expensive than a crane. A disadvantage is the low working range of the Hallen Derrick, it is able to swing 75° from the centerline and can work against a list of up to 15°.


Velle

The Velle derrick is quite similar to the Hallen but without use of outriggers. On top of the boom is a T-shaped
yoke A yoke is a wooden beam sometimes used between a pair of oxen or other animals to enable them to pull together on a load when working in pairs, as oxen usually do; some yokes are fitted to individual animals. There are several types of yoke, us ...
assembled. Also here, the guys serve for topping and lowering the boom but they are fastened on the yoke with four short, steel-wire hanger-ropes. The ends of the topping and lowering ends of the halyard are secured to half-barrels on one winch. In this way the boom moves in the same speed as the winch veers the topping end of the halyard and hauls the lowering end of the halyard, and vice versa. The slewing ends are also wound on to another half-barrel. For hoisting the cargo, there is a third winch to hoist to cargo on the yoke. Runners decrease swing and rotation of the cargo. A joystick duplex controller steers the Velle derrick.


Stülcken

The patent Stülcken derrick is used for very heavy cargo. It stems from the German shipyard HC Stülcken & Sohn which has been taken over later by neighboring yard
Blohm & Voss Blohm+Voss (B+V), also written historically as Blohm & Voss, Blohm und Voß etc., is a German shipbuilding and engineering company. Founded in Hamburg in 1877 to specialise in steel-hulled ships, its most famous product was the World War II battle ...
. This derrick can handle up to 300
tonnes The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United States ...
. The Stülcken can be made ready in few minutes, dramatically faster than a traditional heavy derrick, doesn't require much space and is operated by four winches. The Stülcken is secured between two V-shaped, unstayed Samson-posts. This makes it possible to let the derrick swing through the posts to reach another hatch. For each post is a hoisting winch, a span winch and a lever that is run by one man only. Bearings, swivels, sheaves and the gooseneck can be unattended for up to four years and create only a friction of about 2%. The span tackles are independent and the halyard is endless. With the revolving suspension heads on the posts it takes ten minutes to swing all the way through. In the double-pendulum block type, half of the cargo tackle can be anchored to the base of the boom. In order to double the hook speed, the halyard passes through the purchases since one end is secured which reduces the SWL to its half. Typical dimensions of a 275 tonne Stülcken are: 25.5 m length, 0.97 m diameter, 1.5 m to 3.4 m diameter of posts, 18 m apart the posts (upper end) and 8.4 m apart the posts (lower end). The hook of a full-loaded 275 tonne Stülcken can move 2.3 m per minute. If only one purchase is secured and the derrick is loaded with 137 tonnes the hook gains velocity to 4.6 m per min. Even more speed can be gained when the winch ratios are reduced to 100 tonnes (triple speed) and 68 tonnes (quadruple speed). Detaching the union table the double-pendulum block type of Stülcken is able to swing through which allows the lower blocks to swing freely to each side of the boom. In this way the derrick reaches a vertical position. A bullrope easily pulls the derrick to the other side until the weight of the cargo tips the derrick over. The span tackles now have the weight on the other side. The union table is fixed again and the derrick can start its work on the other side. There are also Stülcken with single-pendulum blocks. At this type the cargo hook is detached and the lower and upper cargo block are hauled into the center of the Stülcken. To tip the derrick over the gravity is here used again. A derrick helps pump oil in most offshore rigs.


See also

* Crane *
Gyn A gyn is an improvised three legged lifting device used on sailing ships. It provides more stability than a derrick or sheers, and requires no rigging for support. Without additional support, however, it can only be used for lifting things dire ...
* Hoist *
Lighter A lighter is a portable device which creates a flame, and can be used to ignite a variety of items, such as cigarettes, gas lighter, fireworks, candles or campfires. It consists of a metal or plastic container filled with a flammable liquid or c ...
*
Pumpjack A pumpjack is the overground drive for a reciprocating piston pump in an oil well. It is used to mechanically lift liquid out of the well if there is not enough bottom hole pressure for the liquid to flow all the way to the surface. The arra ...
*
Sheers Shear legs, also known as sheers, shears, or sheer legs, are a form of two-legged lifting device. Shear legs may be permanent, formed of a solid A-frame and supports, as commonly seen on land and the floating sheerleg, or temporary, as aboard a ...


References


Further reading

* A swinging derrick white.


External links

*{{Commonscatinline, Derricks Industrial equipment Lifting equipment