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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] |
Oostpoort Delft
Oostpoort (; en, East Gate) is a neighborhood in the borough Amsterdam-Oost in Amsterdam, Netherlands. The neighborhood is situated at between the Linnaeusstraat, the Ringvaart, the Amsterdam–Arnhem railway, and the Amsterdam–Zutphen railway.De Staat van Oostpoort 2013 Amsterdam-Oost. Retrieved on 30 June 2014. Initially, the area was named ''Polderweggebied'' after the Polderweg, which is a road running through it. Between 1885 and 1921, the Oostergasfabriek (Eastern Gas Factory) was located in the area. After the factory was closed, the neighborhood became a business area. In the early 2000s, multiple buildings were demolished and the terrain was Environmental remediation, remediated. In 2007, the first new buildings were constructed. In 2008, the neighborhood was renamed ''Oostp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
181 PoortBrug Leeuwarden
Year 181 ( CLXXXI) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Aurelius and Burrus (or, less frequently, year 934 ''Ab urbe condita''). The denomination 181 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Roman Empire * Imperator Lucius Aurelius Commodus and Lucius Antistius Burrus become Roman Consuls. * The Antonine Wall is overrun by the Picts in Britannia (approximate date). Oceania * The volcano associated with Lake Taupō in New Zealand erupts, one of the largest on Earth in the last 5,000 years. The effects of this eruption are seen as far away as Rome and China. Births * April 2 – Xian of Han, Chinese emperor (d. 234) * Zhuge Liang, Chinese chancellor and regent (d. 234) Deaths * Aelius Aristides, Greek orator and wr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotation Around A Fixed Axis
Rotation around a fixed axis is a special case of rotational motion. The fixed-axis hypothesis excludes the possibility of an axis changing its orientation and cannot describe such phenomena as wobbling or precession. According to Euler's rotation theorem, simultaneous rotation along a number of stationary axes at the same time is impossible; if two rotations are forced at the same time, a new axis of rotation will appear. This article assumes that the rotation is also stable, such that no torque is required to keep it going. The kinematics and dynamics of rotation around a fixed axis of a rigid body are mathematically much simpler than those for free rotation of a rigid body; they are entirely analogous to those of linear motion along a single fixed direction, which is not true for ''free rotation of a rigid body''. The expressions for the kinetic energy of the object, and for the forces on the parts of the object, are also simpler for rotation around a fixed axis, than for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beam (structure)
A beam is a structural element that primarily resists Structural load, loads applied laterally to the beam's axis (an element designed to carry primarily axial load would be a strut or column). Its mode of Deflection (engineering), deflection is primarily by bending. The loads applied to the beam result in reaction forces at the beam's support points. The total effect of all the forces acting on the beam is to produce shear forces and bending moments within the beams, that in turn induce internal stresses, strains and deflections of the beam. Beams are characterized by their manner of support, profile (shape of cross-section), equilibrium conditions, length, and their material. Beams are traditionally descriptions of building or civil engineering structural elements, where the beams are horizontal and carry vertical loads. However, any structure may contain beams, for instance automobile frames, aircraft components, machine frames, and other mechanical or structural systems. In th ... [...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] |
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 and tear on the lifting machine. Counterweights are often used in traction lifts (elevators), cranes and funfair rides. In these applications, the expected load multiplied by the distance that load will be spaced from the central support (called the "tipping point") must be equal to the counterweight's mass times its distance from the tipping point in order to prevent over-balancing either side. This distance times mass is called the load moment. A counterbalance is a weight or force that balances or offsets another as when two objects of equal weight, power, or influence are acting in opposition to each other. The objects are then said to be in counterbalance. Counterweights in action Trebuchet: There are five major components of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hinge
A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation: all other Translation (geometry), translations or rotations being prevented, and thus a hinge has one degree of freedom. Hinges may be made of Flexure bearing, flexible material or of moving components. In biology, many joints function as hinges, like the elbow joint. History Ancient remains of stone, marble, wood, and bronze hinges have been found. Some date back to at least Ancient Egypt. In Ancient Rome, hinges were called wikt:cardo#Latin, cardō and gave name to the goddess Cardea and the main street Cardo. This name cardō lives on figuratively today as "the chief thing (on which something turns or depends)" in words such as ''wikt:cardinal#English, cardinal''. According to the OED, the English word hinge is related to ''wikt:hang#English, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bridge Deck
A deck is the surface of a bridge. A structural element of its superstructure, it may be constructed of concrete, steel, open grating, or wood. Sometimes the deck is covered by a railroad bed and track, asphalt concrete, or other form of pavement for ease of vehicle crossing. A concrete deck may be an integral part of the bridge structure (T-beam or double tee structure) or it may be supported with I-beams or steel girders. When a bridge deck is installed in a through truss, it is sometimes called a floor system. A suspended bridge deck will be suspended from the main structural elements on a suspension or arch bridge. On some bridges, such as a tied-arch or a cable-stayed, the deck is a primary structural element, carrying tension or compression to support the span. A deck bridge is one in which the deck itself is the main structural element, itself carrying the roadway. Contrast to a truss bridge which may carry a deck on the top chords or bottom chords of a structural ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bascule Bridge
A bascule bridge (also referred to as a drawbridge or a lifting bridge) is a moveable bridge with a counterweight that continuously balances a span, or leaf, throughout its upward swing to provide clearance for boat traffic. It may be single- or double-leafed. The name comes from the French term for balance scale, which employs the same principle. Bascule bridges are the most common type of movable span because they open quickly and require relatively little energy to operate, while providing the possibility for unlimited vertical clearance for marine traffic. History Bascule bridges have been in use since ancient times, but until the adoption of steam power in the 1850s, very long, heavy spans could not be moved quickly enough for practical application. Types There are three types of bascule bridge and the counterweights to the span may be located above or below the bridge deck. The fixed-trunnion (sometimes a "Chicago" bascule) rotates around a large axle that raises the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Folding Bridge
A folding bridge is a type of moveable bridge. An example of a folding bridge is the Hörnbrücke ( Hörn Bridge) in the city of Kiel in the German state of Schleswig-Holstein. It is a three-segment bascule bridge that folds in the shape of the letter ''N''. See also * Bascule bridge * Double-beam drawbridge * Drawbridge * Moveable bridges 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 ... for a list of other moveable bridge types Moveable bridges {{Bridge-type-stub Bridges by structural type ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Langlois Bridge
Langlois Bridge (French: ''Pont de Langlois'') was a double-beam drawbridge in Arles, France, which was the subject of several paintings by Vincent van Gogh in 1888. Being one of eleven drawbridges built by a Dutch engineer along the channel from Arles to Port-de-Bouc, this bridge might have reminded the artist of his homeland. History New canals were opened up in southern France as they were needed to expand the network of canals. In the 19th century a canal was built from Arles to Bouc, located on the Mediterranean Sea. Locks and bridges were built, too, to manage water and road traffic. Just outside Arles, the first bridge was the officially titled "Pont de Réginelle" but better known by the keeper's name as "Pont de Langlois". In 1930, the original drawbridge was replaced by a reinforced concrete structure which, in 1944, was blown up by the retreating Germans who destroyed all the other bridges along the canal except for the one at Fos. The Fos Bridge was dismantled in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
