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Guyed Mast
A guyed mast is a tall thin vertical structure that depends on guy lines (diagonal tensioned cables attached to the ground or a base) for stability. The mast itself has the compressive strength to support its own weight, but does not have the shear strength to stand unsupported or bear loads. It requires guy lines to stay upright and to resist lateral (shear) forces such as wind loads. Examples include masts on sailing vessels, towers for telecommunications, meteorology, and masts on cranes, power shovels, draglines, and derricks, starting with the simple gin pole. Applications The principal applications of guyed masts are the masts of sailing vessels, guyed towers, and as the main tower of heavy equipment such as cranes, power shovels, draglines, and derricks, the simplest of which is the gin pole. Guyed masts are frequently used for radio masts and towers. The mast can either support radio antennas (for VHF, UHF and other microwave bands) mounted at its top, or th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gin Pole
A gin pole is a pivoting guyed_mast, mast supported by one or more guy-wires that uses a pulley or block and tackle mounted 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 ''mast'', ''boom'', or ''spar'') is secured with three or more guys. These are manipulated to move the load laterally, with up and down controlled by the pulley or block. In tower construction, a gin pole can also be “jumped” up the completed sections of a tower to lift the higher sections into place. Etymology The gin pole is derived from a gyn, and considered a form of derrick, called a standing derrick or pole derrick, distinguished from sheers (or ''shear legs'') by having a single boom rather than a two-legged one. Applications In addition to being used as simple lifting devices in field operations such as construction, logging, loading and unloading boats, and emergency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guywire
A guy-wire, guy-line, guy-rope, down guy, or stay, also called simply a guy, is a tensioned cable designed to add stability to a freestanding structure. They are used commonly for ship masts, radio masts, wind turbines, utility poles, and tents. A thin vertical mast supported by guy wires is called a guyed mast. Structures that support antennas are frequently of a lattice construction and are called "towers". One end of the guy is attached to the structure, and the other is anchored to the ground at some distance from the mast or tower base. The tension in the diagonal guy-wire, combined with the compression and buckling strength of the structure, allows the structure to withstand lateral loads such as wind or the weight of cantilevered structures. They are installed radially, usually at equal angles about the structure, in trios and quads. As the tower leans a bit due to the wind force, the increased guy tension is resolved into a compression force in the tower or ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medium Frequency
Medium frequency (MF) is the International Telecommunication Union, ITU designation for Radio frequency, radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometers (1000 to 100 m). Frequencies immediately below MF are denoted as low frequency (LF), while the first band of higher frequencies is known as high frequency (HF). MF is mostly used for AM broadcasting, AM radio broadcasting, Radio beacon, navigational radio beacons, maritime ship-to-shore communication, and transoceanic air traffic control. Propagation Radio waves at MF wavelengths propagate via ground waves and reflection from the ionosphere (called skywaves). Ground waves travel just above the earth's surface, following the terrain. At these wavelengths, they can bend (diffraction, diffract) over hills, and travel be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trispastos
A treadwheel crane () is a wooden, human powered hoisting and lowering device. It was primarily used during the Roman period and the Middle Ages in the building of castles and cathedrals. The often heavy charge is lifted as the individual inside the treadwheel crane walks. History Ancient Rome The Roman ''polyspaston'' crane, from Ancient Greek πολύσπαστον (polúspaston, “compound pulley”), when worked by four men at both sides of the winch, could lift 3000 kg. In case the winch has been replaced by a treadwheel, the maximum load even doubled to 6000 kg 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 ancient Egyptian pyramids, where about 50 men were needed to move a 2.5 ton stone block up the ramp (50 kg per person), the lifting capability of the Roman ''Polyspaston'' proved to be ''60 times'' more efficient (3000 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sendeturm Jauerling
The Sendeturm Jauerling (Jauerling Transmission Tower) is a tower for directional radio services, FM and TV broadcasting on the Jauerling mountain in Austria. Sendeturm Jauerling was built in 1958. It consists of a 35-metre-high free-standing steel framework tower, which carries a guyed steel tube mast on the top and has a total height of 141 metres. External links * http://www.wabweb.net/radio/frames/radioaf5.htm * http://www.skyscraperpage.com/diagrams/?b46990 See also *List of towers The tallest structure in the world is the Burj Khalifa skyscraper at . Listed are guyed masts (such as telecommunication masts), self-supporting towers (such as the CN Tower), skyscrapers (such as the Willis Tower), oil platforms, electricity ... Radio in Austria Towers in Austria {{Austria-struct-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stays (nautical)
Stays are ropes, wires, or rods on sailing Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the ''water'' (sailing ship, sailboat, raft, Windsurfing, windsurfer, or Kitesurfing, kitesurfer), on ''ice'' (iceboat) or on ''land'' (Land sa ... vessels that run fore-and-aft along the centerline from the masts to the hull, deck, bowsprit, or to other masts which serve to stabilize the masts. A stay is part of the standing rigging and is used to hold a mast upright. It is a large strong rope, wire or rod extending from the upper end of each mast and running down towards the deck of the vessel in a midships -and- direction. The shrouds serve a similar function but extend on each side of the mast and provide support in the athwartships direction. The object of both is to prevent the masts from falling down but the stays also prevent springing, when the ship is pitching deep. Thus stays are fore and aft. Those led aft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shroud (sailing)
On a sailing ship, the shrouds are the standing rigging which holds the mast (sailing), mast up from side to side. There is frequently more than one shroud on each side of the boat. Usually a shroud will connect at the top of the mast, and additional shrouds might connect partway down the mast, depending on the design of the boat. Shrouds terminate at their bottom ends at the Chainplate, chain plates, which are tied into the hull. They are sometimes held outboard by Chains (nautical), channels, a ledge that keeps the shrouds clear of the gunwales.''The Lore of Ships,'' ed. by Bengt Kihlberg. Göteborg :Tre tryckare & New York: Holt, Rinehart & Winston, 1963. Shrouds are attached symmetrically on both the port (nautical), port and starboard sides. For those shrouds which attach high up the mast, a structure projecting from the mast must be used to increase the angle of the shroud at the attachment point, providing more support to the mast. On most sailing boats, such structures ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crane (machine)
A crane is a machine used to move materials both vertically and horizontally, utilizing a system of a boom, hoist, wire ropes or chains, and sheaves for lifting and relocating heavy objects within the swing of its boom. The device uses one or more simple machines, such as the lever and pulley, to create mechanical advantage to do its work. Cranes are commonly employed in transportation for the loading and unloading of freight, in construction for the movement of materials, and in manufacturing for the assembling of heavy equipment. The first known crane machine was the shaduf, a water-lifting device that was invented in ancient Mesopotamia (modern Iraq) and then appeared in ancient Egyptian technology. Construction cranes later appeared in ancient Greece, where they were powered by men or animals (such as donkeys), and used for the construction of buildings. Larger cranes were later developed in the Roman Empire, employing the use of human treadwheels, permitting the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traill County, North Dakota
Traill County is a County (United States), county in the U.S. state of North Dakota. As of the 2020 United States census, 2020 census, the population at 7,997, and was estimated to be 7,989 in 2024. The county seat is Hillsboro, North Dakota, Hillsboro and the largest city is Mayville, North Dakota, Mayville. History The Dakota Territory legislature created the county on January 12, 1875, with areas partitioned from Barnes County, North Dakota, Burbank (now Barnes), Cass County, North Dakota, Cass, and Grand Forks County, Grand Forks Counties. It was named for Walter John Strickland Traill, an employee of the Hudson's Bay Company and son of Canadian pioneer Catharine Parr Traill. The first county building was a small single-story building in Caledonia, North Dakota, Caledonia. Several replacement courthouses were built during the late 19th century and several votes to move the county seat to Mayville narrowly failed. Efforts to move the county seat to Hillsboro were more success ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KRDK-TV Mast
The KRDK-TV mast is a television transmitting tower northeast of Galesburg in Traill County, North Dakota, United States. It was completed in 1966 and is used by KRDK-TV (formerly KXJB-TV), which is licensed to Valley City, serving the Fargo and Grand Forks TV markets. At 2,060 ft (627.9 m), it is currently the tallest structure in the United States, the second-tallest structure in the Western Hemisphere and the seventh-tallest structure in the world. It stands taller than the nearby KVLY-TV mast in Blanchard, North Dakota, which was previously 3 ft (0.9 m) taller until the removal of a VHF antenna reduced its height in 2019. The KRDK-TV antenna has an effective radiated power (ERP) of 285 kW. The station and tower are owned by Major Market Broadcasting. It replaced the station's previous mast, a tower northeast of Valley City, North Dakota (or southwest of Pillsbury) which was sold to KOVC, an AM radio station. Collapses The mast has fallen and been rebui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electricity Pylon
A transmission tower (also electricity pylon, hydro tower, or pylon) is a tall structure, usually a lattice tower made of steel that is used to support an overhead power line. In electrical grids, transmission towers carry high voltage, high-voltage transmission lines that transport bulk electric power from generating stations to electrical substations, from which electricity is delivered to end consumers; moreover, utility poles are used to support low voltage, lower-voltage electric power transmission, sub-transmission and distribution lines that transport electricity from substation, substations to electricity customers. There are four categories of transmission towers: (i) the suspension tower, (ii) the Dead-end tower#Termination pylon, dead-end terminal tower, (iii) the Dead-end tower, tension tower, and (iv) the transposition tower. The heights of transmission towers typically range from , although when longer spans are needed, such as for crossing water, taller towers are s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
