|
Rigger (industry)
A rigger is a skilled tradesperson who specializes in the assistance of manual mechanical advantage device comprising pulley, block and tackle or motorised such as a crane or derrick or chain hoists (chain fall) or capstan winch. Etymology The term comes from the days of sailing ships, when a rigger was a person who worked with rigging, that is, ropes for hoisting the sails. Sailors could put their rope skills to work in lifting and hauling. In an era before mechanical haulage and cranes, ropes, pulleys and muscle power were all that was available to move heavy objects. A specialized subset are telecommunication riggers, entertainment industry riggers. In time, rigging became a trade in itself, giving rise to modern usages with some original terminology remaining, with its roots all but forgotten. Description Riggers attach loads of equipment to cranes or structures using shackles, cables, chains, clamps or straps, employing pulleys, winches, lifts or chain hoists (aka cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanical Advantage Device
A simple machine that exhibits mechanical advantage is called a mechanical advantage device - e.g.: * Lever: The beam shown is in static equilibrium around the fulcrum. This is due to the moment created by vector force ''"A"'' counterclockwise (moment ''A''*a) being in equilibrium with the moment created by vector force ''"B"'' clockwise (moment ''B''*b). The relatively low vector force ''"B"'' is translated in a relatively high vector force ''"A"''. The force is thus increased in the ratio of the forces ''A : B'', which is equal to the ratio of the distances to the fulcrum ''b : a''. This ratio is called the mechanical advantage. This idealised situation does not take into account friction. * Wheel and axle motion (e.g. screwdrivers, doorknobs): A wheel is essentially a lever with one arm the distance between the axle and the outer point of the wheel, and the other the radius of the axle. Typically this is a fairly large difference, leading to a proportionately large mechanical a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulley
A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt. In the case of a pulley supported by a frame or shell that does not transfer power to a shaft, but is used to guide the cable or exert a force, the supporting shell is called a block, and the pulley may be called a sheave. A pulley may have a groove or grooves between flanges around its circumference to locate the cable or belt. The drive element of a pulley system can be a rope, cable, belt, or chain. The earliest evidence of pulleys dates back to Ancient Egypt in the Twelfth Dynasty (1991-1802 BCE) and Mesopotamia in the early 2nd millennium BCE. In Roman Egypt, Hero of Alexandria (c. 10-70 CE) identified the pulley as one of six simple machines used to lift weights. Pulleys are assembled to form a block and tackle in order to provide mechanical advantage to apply large forces. Pulleys are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block And Tackle
A block and tackle or only tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads. The pulleys are assembled to form blocks and then blocks are paired so that one is fixed and one moves with the load. The rope is threaded through the pulleys to provide mechanical advantage that amplifies the force applied to the rope. Hero of Alexandria described cranes formed from assemblies of pulleys in the first century. Illustrated versions of Hero's ''Mechanica'' (a book on raising heavy weights) show early block and tackle systems. Overview A block is a set of pulleys or sheaves mounted on a single frame. An assembly of blocks with a rope threaded through the pulleys is called tackle. The process of threading ropes or cables through blocks is called "reeving", and a threaded block and tackle is said to have been "rove". A block and tackle system amplifies the tension force in the rope to lift heavy loads. They are common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crane (machine)
A crane is a type of machine, generally equipped with a hoist rope, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It is mainly used for lifting heavy objects and transporting them to other places. The device 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 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, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Derrick
A derrick is a lifting device composed at minimum of one guyed mast, as in a gin pole, 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, 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, and known as floating derricks and sheerlegs. The term derrick is also applied to the framework supporting a drilling apparatus in an oil rig. The derrick derives its name from a type of gallows named after Thomas Derrick, an Elizabethan era English executioner. Types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hoist (device)
A hoist is a device used for lifting or lowering a load by means of a drum or lift-wheel around which rope or chain wraps. It may be manually operated, electrically or pneumatically driven and may use chain, fiber or wire rope as its lifting medium. The most familiar form is an elevator, the car of which is raised and lowered by a hoist mechanism. Most hoists couple to their loads using a lifting hook. Today, there are a few governing bodies for the North American overhead hoist industry which include the Hoist Manufactures Institute, ASME, and the Occupational Safety and Health Administration. HMI is a product counsel of the Material Handling Industry of America consisting of hoist manufacturers promoting safe use of their products. Types The word “hoist” is used to describe many different types of equipment that lift and lower loads. For example, many people use “hoist” to describe an elevator. The information contained here pertains specially to overhead, cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capstan (nautical)
A capstan is a vertical- axled rotating machine developed for use on sailing ships to multiply the pulling force of seamen when hauling ropes, cables, and hawsers. The principle is similar to that of the windlass, which has a horizontal axle. History The word, connected with the Old French ''capestan'' or ''cabestan(t)'', from Old Provençal ''cabestan'', from ''capestre'' "pulley cord," from Latin ''capistrum'', -a halter, from ''capere'', to take hold of, seems to have come into English (14th century) from Portuguese or Spanish shipmen at the time of the Crusades. Both device and word are considered Spanish inventions. Early form In its earliest form, the capstan consisted of a timber mounted vertically through a vessel's structure which was free to rotate. Levers, known as bars, were inserted through holes at the top of the timber and used to turn the capstan. A rope wrapped several turns around the drum was thus hauled upon. A rudimentary ratchet was provided to hold t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sailing Ship
A sailing ship is a sea-going vessel that uses sails mounted on masts to harness the power of wind and propel the vessel. There is a variety of sail plans that propel sailing ships, employing square-rigged or fore-and-aft sails. Some ships carry square sails on each mast—the brig and full-rigged ship, said to be "ship-rigged" when there are three or more masts. Others carry only fore-and-aft sails on each mast, for instance some schooners. Still others employ a combination of square and fore-and-aft sails, including the barque, barquentine, and brigantine. Early sailing ships were used for river and coastal waters in Ancient Egypt and the Mediterranean. The Austronesian peoples developed maritime technologies that included the fore-and-aft crab-claw sail and with catamaran and outrigger hull configurations, which enabled the Austronesian expansion into the islands of the Indo-Pacific. This expansion originated in Taiwan BC and propagated through Island Southeast Asia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rigging
Rigging comprises the system of ropes, cables and chains, which support a sailing ship or sail boat's masts—''standing rigging'', including shrouds and stays—and which adjust the position of the vessel's sails and spars to which they are attached—the ''running rigging'', including halyards, braces, sheets and vangs. Etymology According to the Encyclopædia Britannica Eleventh Edition "rigging" derives from Anglo-Saxon ''wrigan'' or ''wringing'', "to clothe". The same source points out that "rigging" a sailing vessel refers to putting all the components in place to allow it to function, including the masts, spars, sails and the rigging. Types of rigging Rigging is divided into two classes, ''standing'', which supports the mast (and bowsprit), and ''running'', which controls the orientation of the sails and their degree of reefing. Configurations differ for each type of rigging, between ''fore-and-aft rigged'' vessels and ''square-rigged'' vessels. Standing Standin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Tower Technician
Tower climbers are also known as wireless service technicians, cell site technicians, cell site engineers, aerial technician, field technicians, tower hands, and tower dogs. They specialize in maintenance, installation, and decommissioning of cellular and radio tower components such as coaxial cable, antennas, radios, fiber optic cable and broadcast equipment for cell phones, television, radio etc. Description Tower climbers perform routine inspections and tests on broadcasting towers, and may also be called upon to perform repairs and to provide input when plans for new equipment are being developed. Along with the installers of the tower antennas, other crews climb the towers to perform condition checks of the towers, guy lines and lighting systems. One of the most demanding aspects of many tower climber jobs is hauling materials and tools up to the proper installation height on the tower. In most cases, the climber scales the tower to the desired height and lowers a rope t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entertainment Rigging
Rigging in entertainment can be broken down into two main subjects – theatrical rigging and arena-style rigging. All the same skills apply in both genres. The first takes place in a theatre, and typically involves the theatre's permanent fly system. The other in an arena or "exposed structure venue" such as a convention center, ballroom, warehouse etc. Circus rigging, comprising aerial acrobatic apparatuses that support human beings under dynamic loading conditions, and stabilization rigging for large scale fabric tension structures (big tops), is, perhaps, under appreciated in the general rigging field, and may be considered by some to be a separate field. However, the principles of physics and the standards of engineering that apply to theatrical and arena rigging still hold true in circus rigging, and much of the same equipment and many of the same devices are commonly used. All the same skills apply in this genre as well. Chain motors and trusses are not used as often in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
