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Sheave
Sheave without a rope A pulley is a wheel on an axle or shaft enabling a taut cable or belt passing over the wheel to move and change direction, or transfer power between itself and a shaft. 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. History The earliest evidence of pulleys dates back to Ancient Egypt in the Twelfth Dynasty (1991–1802 BC) and Mesopotamia in the early 2nd millennium BC. In Roman Egypt, Hero of Alexandria (c. 10–70 AD) 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 also assembled as part of belt and chain drives in order to transmit power from one rotating shaft to another. Plutarch's ''Parallel Lives'' recounts a scene where Archimedes proved the effectiveness of ... [...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, used to provide tension and 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Belt (mechanical)
A belt is a loop of flexible material used to link two or more rotating shafts mechanically, most often parallel. Belts may be used as a source of motion, to transmit power efficiently or to track relative movement. Belts are looped over pulleys and may have a twist between the pulleys, and the shafts need not be parallel. In a two pulley system, the belt can either drive the pulleys normally in one direction (the same if on parallel shafts), or the belt may be crossed, so that the direction of the driven shaft is reversed (the opposite direction to the driver if on parallel shafts). The belt drive can also be used to change the speed of rotation, either up or down, by using different sized pulleys. As a source of motion, a conveyor belt is one application where the belt is adapted to carry a load continuously between two points. History The mechanical belt drive, using a pulley machine, was first mentioned in the text of the ''Dictionary of Local Expressions'' by the Han ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block (sailing)
In sailing, a block is a single or multiple pulley. One or a number of '' sheaves'' are enclosed in an assembly between ''cheeks'' or ''chocks''. In use, a block is fixed to the end of a line, to a spar, or to a surface. A line (rope) is ''reeved'' through the sheaves, and maybe through one or more matching blocks at some far end, to make up a tackle. The ''purchase'' of a tackle refers to its mechanical advantage. In general the more sheaves in the blocks that make up a tackle, the higher its mechanical advantage. The matter is slightly complicated by the fact that every tackle has a ''working end'' where the final run of rope leaves the last sheave. More mechanical advantage can be obtained if this end is attached to the moving load rather than the fixed end of the tackle. There are various types of blocks that are used in sailing. Some blocks are used to increase mechanical advantage and others are used simply to change the direction of a line. A ''ratchet block'' turn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulley In Oil Well
Sheave without a rope A pulley is a wheel on an axle or shaft enabling a taut cable or belt passing over the wheel to move and change direction, or transfer power between itself and a shaft. 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. History The earliest evidence of pulleys dates back to Ancient Egypt in the Twelfth Dynasty (1991–1802 BC) and Mesopotamia in the early 2nd millennium BC. In Roman Egypt, Hero of Alexandria (c. 10–70 AD) 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 also assembled as part of belt and chain drives in order to transmit power from one rotating shaft to another. Plutarch's ''Parallel Lives'' recounts a scene where Archimedes proved the effectiveness ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wire Rope
Steel wire rope (right hand lang lay) Wire rope is composed of as few as two solid, metal wires twisted into a helix that forms a composite ''rope'', in a pattern known as ''laid rope''. Larger diameter wire rope consists of multiple strands of such laid rope in a pattern known as ''cable laid''. Manufactured using an industrial machine known as a strander, the wires are fed through a series of barrels and spun into their final composite orientation. In stricter senses, the term ''wire rope'' refers to a diameter larger than , with smaller gauges designated cable or cords. Initially wrought iron wires were used, but today steel is the main material used for wire ropes. Historically, wire rope evolved from wrought iron chains, which had a record of mechanical failure. While flaws in chain links or solid steel bars can lead to catastrophic failure A catastrophic failure is a sudden and total failure from which recovery is impossible. Catastrophic failures often lead to cascadi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Groove (machining)
In manufacturing or mechanical engineering a groove is a long and narrow indentation built into a material, generally for the purpose of allowing another material or part to move within the groove and be guided by it. Examples include: # A canal cut in a hard material, usually metal. This canal can be round, oval or an arc in order to receive another component such as a boss, a tongue or a gasket. It can also be on the circumference of a dowel, a bolt, an axle or on the outside or inside of a tube or pipe etc. This canal may receive a circlip, an o-ring, or a gasket. # A depression on the entire circumference of a cast or machined wheel, a pulley or sheave. This depression may receive a cable, a rope or a belt. # A longitudinal channel formed in a hot rolled rail profile such as a grooved rail. This groove is for the flange on a train wheel. Grooves were used by ancient Roman engineers to survey land. See also * Fluting (architecture) * Gland (engineerin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ideal Mechanical Advantage
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for this is the ''law of the lever.'' Machine components designed to manage forces and movement in this way are called mechanisms. An ideal mechanism transmits power without adding to or subtracting from it. This means the ideal machine does not include a power source, is frictionless, and is constructed from rigid bodies that do not deflect or wear. The performance of a real system relative to this ideal is expressed in terms of efficiency factors that take into account departures from the ideal. Levers The lever is a movable bar that pivots on a fulcrum attached to or positioned on or across a fixed point. The lever operates by applying forces at different distances from the fulcrum, or pivot. The location of the fulcrum determi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crane Pulley 4x
Crane or cranes may refer to: Common meanings * Crane (bird), a large, long-necked bird * Crane (machine), industrial machinery for lifting ** Crane (rail), a crane suited for use on railroads People and fictional characters * Crane (surname), including a list of people and fictional characters with the surname * Crane (given name), a list of people Places Barbados * The Crane, Saint Philip, Barbados United Kingdom * River Crane, Dorset * River Crane, London, a small river of London, branch to the Thames ** Crane (ward), an former electoral ward of Hillingdon London Borough Council that existed from 1978 to 2002 United States * Crane, Indiana, a town * Crane, Missouri, a town * Crane, Montana, a census-designated place and unincorporated community * Crane, Oregon, a census-designated place and unincorporated community * Crane County, Texas ** Crane, Texas, a city and the county seat * Crane, Virginia, an unincorporated community * Crane, Washington, an unincorpo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simple Machines
Simple Machines was an American independent record label in Arlington, Virginia. The label was founded by Derek Denckla and Jenny Toomey and Brad Sigal while both were living in the Positive Force House in north Arlington, but Sigal and eventually Denckla stepped back from involvement. In 1990-91 Kristin Thomson stepped up and co-masterminded the project with Toomey and they started a new group house near Positive Force's. At its peak, the label had four paid workers: Toomey, Thomson, Pat Graham and Mickey Menard. The label was formed to "find creative ways to avoid the established and boring music business." Biography The label came into existence in 1989 working toward the 1990 release of the ''Simple Machines 7"'' series. The ''Working Holiday!'' 7" series followed. Simple Machines promoted cooperation with other indie labels all over the United States, and the "sell it at a fair price" ethic. The label also released a compilation of bands covering their "favorite Beat H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archimedes
Archimedes of Syracuse ( ; ) was an Ancient Greece, Ancient Greek Greek mathematics, mathematician, physicist, engineer, astronomer, and Invention, inventor from the ancient city of Syracuse, Sicily, Syracuse in History of Greek and Hellenistic Sicily, Sicily. Although few details of his life are known, based on his surviving work, he is considered one of the leading scientists in classical antiquity, and one of the greatest mathematicians of all time. Archimedes anticipated modern calculus and mathematical analysis, analysis by applying the concept of the Cavalieri's principle, infinitesimals and the method of exhaustion to derive and rigorously prove many geometry, geometrical theorem, theorems, including the area of a circle, the surface area and volume of a sphere, the area of an ellipse, the area under a parabola, the volume of a segment of a paraboloid of revolution, the volume of a segment of a hyperboloid of revolution, and the area of a spiral. Archimedes' other math ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parallel Lives
* Culture of ancient Greece Culture of ancient Rome Ancient Greek biographical works Ethics literature History books about ancient Rome Cultural depictions of Gaius Marius Cultural depictions of Mark Antony Cultural depictions of Cicero Depictions of Julius Caesar in literature Cultural depictions of Pompey Cultural depictions of Marcus Junius Brutus Cultural depictions of Marcus Licinius Crassus Cultural depictions of Theseus Cultural depictions of Romulus and Remus Cultural depictions of Cato the Younger Cultural depictions of Sulla Cultural depictions of Alexander the Great The ''Parallel Lives'' (, ''Bíoi Parállēloi''; ) is a series of 48 biographies of famous men written in Greek by the Greco-Roman philosopher, historian, and Apollonian priest Plutarch, probably at the beginning of the second century. The lives are arranged in pairs to illuminate their common moral virtues or failings. While any historically valuable similarities are often forced, these ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
