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Drawbridges
A drawbridge or draw-bridge is a type of moveable bridge typically at the entrance to a castle or tower surrounded by a moat. In some forms of English, including American English, the word ''drawbridge'' commonly refers to all types of moveable bridges, such as bascule bridges, vertical-lift bridges and swing bridges, but this article concerns the narrower historical definition of the term where the bridge is used in a defensive structure. As used in castles or defensive structures, drawbridges provide access across defensive structures when lowered, but can quickly be raised from within to deny entry to an enemy force. Castle drawbridges Medieval castles were usually defended by a ditch or moat, crossed by a wooden bridge. In early castles the bridge might be designed to be destroyed or removed in the event of an attack, but drawbridges became very common. A typical arrangement would have the drawbridge immediately outside a gatehouse, consisting of a wooden deck with on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drawbridge
A drawbridge or draw-bridge is a type of moveable bridge typically at the entrance to a castle or tower surrounded by a moat. In some forms of English, including American English, the word ''drawbridge'' commonly refers to all types of moveable bridges, such as bascule bridges, vertical-lift bridges and swing bridges, but this article concerns the narrower historical definition of the term where the bridge is used in a defensive structure. As used in castles or defensive structures, drawbridges provide access across defensive structures when lowered, but can quickly be raised from within to deny entry to an enemy force. Castle drawbridges Medieval castles were usually defended by a ditch or moat, crossed by a wooden bridge. In early castles the bridge might be designed to be destroyed or removed in the event of an attack, but drawbridges became very common. A typical arrangement would have the drawbridge immediately outside a gatehouse, consisting of a wooden deck with one ed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moveable Bridge
A moveable bridge, or movable bridge, is a bridge that moves to allow passage for boats or barges. In American English, the term is synonymous with , and the latter is the common term, but drawbridge can be limited to the narrower, historical definition used in some other forms of English, in which ''drawbridge'' refers to only a specific type of moveable bridge often found in castles . An advantage of making bridges moveable is the lower cost, due to the absence of high piers and long approaches. The principal disadvantage is that the traffic on the bridge must be halted when it is opened for passage of traffic on the waterway. For seldom-used railroad bridges over busy channels, the bridge may be left open and then closed for train passages. For small bridges, bridge movement may be enabled without the need for an engine. Some bridges are operated by the users, especially those with a boat, others by a bridgeman (or bridge tender); a few are remotely controlled using video-cam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double-beam Drawbridge
A double-beam drawbridge, seesaw or folding bridge is a movable bridge . It opens by rotation about a horizontal axis parallel to the water. Historically, the double-beam drawbridge has emerged from the drawbridge. Unlike a drawbridge, a double-beam drawbridge has counterweights, so that opening requires much less energy. Unlike the bascule bridge, the simple drawbridge and the "oorgat" (earhole) bridge, the double-beam drawbridge has two hinges. The road surface is connected to the bottom hinge. Above the hinge is a portal, the hamei gate. A rotating arm, the balance, is attached to this hamei gate. On one side of the balance hangs the counterweight, the balance box, on the other side, the arm is connected to the tip of the bridge deck. So when the bridge goes up, the balance and the bridge deck turn parallel. The drawback of a traditional double-beam drawbridge is that it has a limited clearance height. That is why the balance box sometimes does not hang between the two arms, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helmingham Hall
Helmingham Hall is a moated manor house in Helmingham, Suffolk, England. It was begun by John Tollemache in 1480 and has been owned by the Tollemache family ever since. The house is built around a courtyard in typical late medieval/Tudor style. The house is listed Grade I on the National Heritage List for England, and its park and formal gardens are also Grade I listed on the Register of Historic Parks and Gardens. History The present Helmingham Hall may have been initially constructed in 1510 on the site of an earlier house called Creke Hall. The exterior was altered between 1745 and 1760, again in 1800 by John Nash, and in 1840. The original half-timbered walls have been concealed by brick and tiles. The house is surrounded by a moat 60 feet wide, over which it is reached only by two working drawbridges, which have been pulled up every night since 1510. These were originally operated with a windlass but in recent years this has been replaced by an electric motor. In addit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windlass
The windlass is an apparatus for moving heavy weights. Typically, a windlass consists of a horizontal cylinder (barrel), which is rotated by the turn of a crank or belt. A winch is affixed to one or both ends, and a cable or rope is wound around the winch, pulling a weight attached to the opposite end. The Greek scientist Archimedes was the inventor of the windlass. The oldest depiction of a windlass for raising water can be found in the Book of Agriculture published in 1313 by the Chinese official Wang Zhen of the Yuan Dynasty ( 1290–1333). Uses *Vitruvius, a military engineer writing about 28 BC, defined a machine as "a combination of timber fastened together, chiefly efficacious in moving great weights." About a century later, Hero of Alexandria summarized the practice of his day by naming the "five simple machines" for "moving a given weight by a given force" as the lever, windlass, screw for power, wedge, and tackle block (pulley). Until nearly the end of the nine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portcullis
A portcullis (from Old French ''porte coleice'', "sliding gate") is a heavy vertically-closing gate typically found in medieval fortifications, consisting of a latticed grille made of wood, metal, or a combination of the two, which slides down grooves inset within each jamb of the gateway. Usage Portcullises fortified the entrances to many medieval castles, securely closing off the castle during time of attack or siege. Every portcullis was mounted in vertical grooves in the walls of the castle and could be raised or lowered quickly by means of chains or ropes attached to an internal winch. Portcullises had an advantage over gates in that they could be closed immediately at a time of crisis by a single guard. Often, two portcullises to the main entrance would be used. The one closer to the inside would be closed first, and then the one farther away. This was used to trap the enemy, and often, burning wood or fire-heated sand would be dropped onto them from the roof or murder-h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drawbridge Mentality
A drawbridge mentality is the attitude of people who have migrated to a more exclusive or more "unspoiled" community and then campaign to preserve the tranquility of that community by opposing further inward migration by people or businesses and, possibly, any development or refurbishment, including plans put forward by those already located there. The term can imply a selfish attitude and can be taken as an insult by people who have strong affection for their home locality and wish to protect it from any changes. It is closely related to the NIMBY attitude. There are many factors that can lead to a person developing a drawbridge mentality, and two of the factors are quality of place and migration. When new people migrate into an already populated area, they often bring with them new ideas and practices. Sometimes, the original population is upset with this change and wants to keep things how they were. These individuals “reject change and work to preserve the status quo, adopting a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guthrie Rolling Bridge
A Guthrie rolling bridge was a kind of retractable bridge, an 18th-century version of the drawbridge. It was commonly installed as the access across the narrow steep sided ditches characteristic of the polygonal forts of this era. Rolling bridges were unhinged, and remained horizontal as they were retracted within the gates of a fortification, similar in operation to a modern thrust bridge. Running the bridge out Running the bridge out is effected by pushing it along its rails until the outer two wheels are at the edge of the granite sill of the ditch. When the bridge is pushed beyond this point the two outer wheels do not descend the slopes of the granite slabs but instead the bridge remains in a horizontal position. This is due to the centre axle being offset from the centre of the girders causing the bridge to run on its inner two wheels. The middle two wheels follow along the trays. When the bridge is just less than halfway out, the ends of the centre axle then engage in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palmerston Forts
The Palmerston Forts are a group of forts and associated structures around the coasts of the United Kingdom and Ireland. The forts were built during the Victorian period on the recommendations of the 1860 Royal Commission on the Defence of the United Kingdom, prompted by concerns about the strength of the French Navy, and strenuous debate in Parliament about whether the cost could be justified. The name comes from their association with Lord Palmerston, who was Prime Minister at the time and promoted the idea. The works were also known as Palmerston's Follies, partly because the first ones which were around Portsmouth, had their main armament facing inland to protect Portsmouth from a land-based attack, and thus (as it appeared to some) facing the wrong way to defend from a French attack. The name also derived from the use of the term "folly" to indicate " a costly ornamental building with no practical value". They were criticized because at the time of their completion, the th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trunnion
A trunnion (from Old French "''trognon''", trunk) is a cylindrical protrusion used as a mounting or pivoting point. First associated with cannons, they are an important military development. Alternatively, a trunnion is a shaft that positions and supports a tilting plate. This is a misnomer, as in reality it is a cradle for the true trunnion. In mechanical engineering (see the trunnion bearing section below), it is one part of a rotating joint where a shaft (the trunnion) is inserted into (and turns inside) a full or partial cylinder. Medieval history In a cannon, the trunnions are two projections cast just forward of the center of mass of the cannon and fixed to a two-wheeled movable gun carriage. As they allowed the muzzle to be raised and lowered easily, the integral casting of trunnions is seen by military historians as one of the most important advances in early field artillery. With the creation of larger and more powerful siege guns in the early 15th century, a n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Château Du Plessis-Bourré
Château du Plessis-Bourré is a château in the Loire Valley in France, situated in the commune of Écuillé in the Maine-et-Loire department. Built in less than 5 years from 1468 to 1472 by Finance Minister Jean Bourré, the principal advisor to King Louis XI. The château has not been modified externally since its construction and still has a fully working drawbridge. It was classified as a in 1931. The château was purchased in 1911 by Henry Vaïsse who, when he died in 1956, bequeathed it to his nephew, François Reille-Soult, Duke of Dalmatie, descendant of the marshals of the French empire [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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