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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] |
Madison Street Bridge
{{Disambiguation ...
Madison Street Bridge may refer to: *Madison Street Bridge (Chicago), a crossing of the Chicago River *Madison Street Bridge (Portland, Oregon), the name of two former bridges over the Willamette River The Willamette River ( ) is a major tributary of the Columbia River, accounting for 12 to 15 percent of the Columbia's flow. The Willamette's main stem is long, lying entirely in northwestern Oregon in the United States. Flowing northward b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rack And Pinion
A rack and pinion is a type of linear actuator that comprises a circular gear (the '' pinion'') engaging a linear gear (the ''rack''). Together, they convert rotational motion into linear motion. Rotating the pinion causes the rack to be driven in a line. Conversely, moving the rack linearly will cause the pinion to rotate. A rack and pinion drive can use both straight and helical gears. Though some suggest helical gears are quieter in operation, no hard evidence supports this theory. Helical racks, while being more affordable, have proven to increase side torque on the datums, increasing operating temperature leading to premature wear. Straight racks require a lower driving force and offer increased torque and speed per percentage of gear ratio which allows lower operating temperature and lessens viscal friction and energy use. The maximum force that can be transmitted in a rack and pinion mechanism is determined by the tooth pitch and the size of the pinion as well as the gear ... [...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] |
Jet Bridge
A jet bridge (also termed jetway, jetwalk, airgate, gangway, aerobridge/airbridge, skybridge, finger, airtube, expedited suspended passenger entry system (E-SPES), or its official industry name passenger boarding bridge (PBB)) is an enclosed, movable connector which most commonly extends from an airport terminal gate to an airplane, and in some instances from a port to a boat or ship, allowing passengers to board and disembark without going outside and being exposed to harsh weather. Depending on building design, sill heights, fueling positions, and operational requirements, a jet bridge may be fixed or movable, swinging radially, and/or extending in length. The jetway was invented by Frank Der Yuen. Similar devices are used for astronauts to enter spacecraft, which are installed in the appropriate height of the launch tower. History Before the introduction of jet bridges, passengers normally boarded an aircraft by walking along the ground-level ramp and climbing a set o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferry
A ferry is a ship, watercraft or amphibious vehicle used to carry passengers, and sometimes vehicles and cargo, across a body of water. A passenger ferry with many stops, such as in Venice, Italy, is sometimes called a water bus or water taxi. Ferries form a part of the public transport systems of many waterside cities and islands, allowing direct transit between points at a capital cost much lower than bridges or tunnels. Ship connections of much larger distances (such as over long distances in water bodies like the Mediterranean Sea) may also be called ferry services, and many carry vehicles. History In ancient times The profession of the ferryman is embodied in Greek mythology in Charon, the boatman who transported souls across the River Styx to the Underworld. Speculation that a pair of oxen propelled a ship having a water wheel can be found in 4th century Roman literature "''Anonymus De Rebus Bellicis''". Though impractical, there is no reason why it could not work ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transporter Bridge
A transporter bridge, also known as a ferry bridge or aerial transfer bridge, is a type of movable bridge that carries a segment of roadway across a river. The gondola is slung from a tall span by wires or a metal frame. The design has been used to cross navigable rivers or other bodies of water, where there is a requirement for ship traffic to be able to pass. This has been a rare type of bridge, with fewer than two dozen built. There are just twelve that continue to be used today, including one converted into a lift bridge and one designed as, but not yet operating as, a transporter bridge. History The concept of the transporter bridge was invented in 1873 by Charles Smith (1844–1882), the manager of an engine works in Hartlepool, England. He called it a "bridge ferry" and unsuccessfully presented his ideas to councils in Hartlepool, Middlesbrough, and Glasgow. The first transporter bridge, Vizcaya Bridge was built between Las Arenas and Portugalete, Spain, in 1893. The de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swing Bridge
A swing bridge (or swing span bridge) is a movable bridge that has as its primary structural support a vertical locating pin and support ring, usually at or near to its center of gravity, about which the swing span (turning span) can then pivot horizontally as shown in the animated illustration to the right. Small swing bridges as found over canals may be pivoted only at one end, opening as would a gate, but require substantial underground structure to support the pivot. In its closed position, a swing bridge carrying a road or railway over a river or canal, for example, allows traffic to cross. When a water vessel needs to pass the bridge, road traffic is stopped (usually by traffic signals and barriers), and then motors rotate the bridge horizontally about its pivot point. The typical swing bridge will rotate approximately 90 degrees, or one-quarter turn; however, a bridge which intersects the navigation channel at an oblique angle may be built to rotate only 45 degrees, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tilt Bridge
A tilt bridge is a type of moveable bridge which rotates about fixed endpoints rather than lifting or bending, as with a drawbridge. The tilting Gateshead Millennium Bridge spanning the River Tyne between Gateshead on the south bank and Newcastle upon Tyne, England, on the north is a pedestrian bridge with two large hydraulic rams at each side that tilt the structure back allowing small watercraft to pass under. The pedestrian and cycle pathway is an almost-horizontal curve, suspended above the river from a just-beyond-the-vertical parabolic arch. To raise the bridge, this whole assembly rotates as a single, rigid structure. As the arch tilts lower, the pathway rises, each counterbalancing the other so that a minimum of energy is needed. The resultant appearance in motion leads to it sometimes being called the "eyelid bridge", since its shape is akin to the blinking of an eye if seen from along the river. Two further tilt bridges are known to exist in Belgium, both constructed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submersible Bridge
A submersible bridge is a type of movable bridge that lowers the bridge deck below the water level to permit waterborne traffic to use the waterway. This differs from a lift bridge or table bridge, which operate by raising the roadway. Two submersible bridges exist across the Corinth Canal in Greece, one at each end, in Isthmia and Corinth. They lower the centre span to 8 metres below water level when they give way to ships crossing the channel. The submersible bridge's primary advantage over the similar lift bridge is that there is no structure above the shipping channel and thus no height limitation on ship traffic. This is particularly important for sailing vessels. Additionally, the lack of an above-deck structure is considered aesthetically pleasing, a similarity shared with the Chicago-style bascule bridge and the table bridge. However, the presence of the submerged bridge structure limits the draft of vessels in the waterway. The term ''submersible bridge'' is also somet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retractable Bridge
A retractable bridge is a type of moveable bridge in which the deck can be rolled or slid backwards to open a gap while traffic crosses, usually a ship on a waterway. This type is sometimes referred to as a thrust bridge. Retractable bridges date back to medieval times. Due to the large dedicated area required for this type of bridge, this design is not common. A retractable design may be considered when the maximum horizontal clearance is required (for example, over a canal). Two remaining examples exist in New York City: the Carroll Street Bridge (built 1889) in Brooklyn, and the Borden Avenue Bridge in Queens. A recent example can be found at Queen Alexandra Dock in Cardiff, Wales, where the bridge is jacked upwards before being rolled on wheels. Helix Bridge at Paddington Basin in London is a more unusual example of the type, consisting of a glass shell supported in a helical steel frame, which rotates as it retracts. The Summer Street Bridge over Fort Point Channel in B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Table Bridge
A table bridge is a moveable bridge in which the deck moves along the vertical axis. Four hydraulic pillars under the bridge, two at each end, raise the bridge deck to allow barge traffic to pass beneath it. In contrast to a lift bridge, where the deck is pulled upwards along towers, the deck of a table bridge is pushed upwards by otherwise hidden pillars. The name originates from the fact that when open it resembles a table. The total space required by a table bridge is hardly larger than the bridge deck, which is not the case with a thrust bridge. Unlike a lift bridge this type has only slight visual impact upon its surroundings when closed for use by road traffic. This is very well demonstrated by the '' Pont levant Notre Dame'' at Tournai in Belgium. Examples of table bridges Several rivers and waterways are home to multiple examples of table bridges. These include but are not limited to: :* Erie Canal in New York between Lockport and the Genesee River is home to one o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical-lift Bridge
A vertical-lift bridge or just lift bridge is a type of movable bridge in which a span rises vertically while remaining parallel with the deck. The vertical lift offers several benefits over other movable bridges such as the bascule and swing-span bridges. Generally speaking, they cost less to build for longer moveable spans. The counterweights in a vertical lift are only required to be equal to the weight of the deck, whereas bascule bridge counterweights must weigh several times as much as the span being lifted. As a result, heavier materials can be used in the deck, and so this type of bridge is especially suited for heavy railroad use. The biggest disadvantage to the vertical-lift bridge (in comparison with many other designs) is the height restriction for vessels passing under it, due to the deck remaining suspended above the passageway. Although most vertical-lift bridges use towers, each equipped with counterweights, some use hydraulic jacks located below the deck. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
