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44-558: Gefyra (Greek: Γέφυρα) which literally means bridge may refer to several villages in Greece: The word gefyra (bridge) in Greek also refers to the Rio-Antirio bridge in informal everyday speech, originating from the domain name of the bridge's official internet site. Rio-Antirio bridge The 2,380-metre-long (7,810 ft; 1.48 mi) bridge dramatically improves access to and from

88-422: A "two-tube" shock absorber, this device consists of two nested cylindrical tubes, an inner tube that is called the "working tube" or the "pressure tube", and an outer tube called the "reserve tube". At the bottom of the device on the inside is a compression valve or base valve. When the piston is forced up or down by bumps in the road, hydraulic fluid moves between different chambers via small holes or "orifices" in

132-456: A PSD shock absorber, which still consists of two nested tubes and still contains nitrogen gas, a set of grooves has been added to the pressure tube. These grooves allow the piston to move relatively freely in the middle range of travel (i.e., the most common street or highway use, called by engineers the "comfort zone") and to move with significantly less freedom in response to shifts to more irregular surfaces when upward and downward movement of

176-551: A complete disappearance of the "comfort vs. control" tradeoff, it also reduced pitch during vehicle braking and roll during turns. However, ASD shocks are usually only available as aftermarket changes to a vehicle and are only available from a limited number of manufacturers. Coilover shock absorbers are usually a kind of twin-tube gas charged shock absorber inside the helical road spring. They are common on motorcycles and scooter rear suspensions, and widely used on front and rear suspensions in cars. The principal design alternative to

220-502: A compression valve, whose role has been taken up by the dividing piston, and although it contains nitrogen gas, the gas in a mono-tube shock is under high pressure (260-360 p.s.i. or so) which can actually help it to support some of the vehicle's weight, something which no other shock absorber is designed to do. Mercedes became the first auto manufacturer to install mono-tube shocks as standard equipment on some of their cars starting in 1958. They were manufactured by Bilstein , patented

264-444: A correspondingly effective shock. The next phase in shock absorber evolution was the development of a shock absorber that could sense and respond to not just situational changes from "bumpy" to "smooth" but to individual bumps in the road in a near instantaneous reaction. This was achieved through a change in the design of the compression valve, and has been termed "acceleration sensitive damping" or "ASD". Not only does this result in

308-467: A great future for racing due to its light weight and easy fitment. One of the earliest hydraulic dampers to go into production was the Telesco Shock Absorber, exhibited at the 1912 Olympia Motor Show and marketed by Polyrhoe Carburettors Ltd. This contained a spring inside the telescopic unit like the pure spring type 'shock absorbers' mentioned above, but also oil and an internal valve so that

352-462: A wind tunnel where 70 miles per hour (110 km/h) winds are common. For these reasons, special design and construction techniques were applied. Beneath each pier the seabed was first reinforced and stabilized by driving 200 hollow steel pipes vertically into the ground. The pier footings were not buried into the seabed, but rather rest on a bed of gravel meticulously leveled to an even surface (a difficult endeavor at this depth). During an earthquake,

396-404: Is a dramatic reduction in "foaming" or "aeration", the undesirable outcome of a twin-tube overheating and failing which presents as foaming hydraulic fluid dripping out of the assembly. Twin-tube gas charged shock absorbers represent the vast majority of original modern vehicle suspension installations. Often abbreviated simply as "PSD", this design is another evolution of the twin-tube shock. In

440-419: Is a hydraulic shock absorber, which usually includes a piston, a cylinder, and an oil-filled chamber. The piston is connected to the piston rod, which extends into the cylinder and divides the cylinder into two parts. One chamber is filled with hydraulic oil, while the other chamber contains compressed oil or air. When there is an accident or vibration in the vehicle, the piston moves into the cylinder, forcing

484-508: Is compatible with electronic control. Primary among benefits cited in Multimatic ’s 2010 patent filing is the elimination of performance ambiguity associated with flexible shims, resulting in mathematically predictable, repeatable, and robust pressure-flow characteristics. An extra tube or container of oil connected to the oil compartment of the (main) shock via a flexible pipe (remote reservoir) or inflexible pipe (piggy-back shock). Increases

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528-400: Is constantly evolving due to the continuous improvement of vehicle dynamics and passenger comfort. In common with carriages and railway locomotives, most early motor vehicles used leaf springs . One of the features of these springs was that the friction between the leaves offered a degree of damping, and in a 1912 review of vehicle suspension, the lack of this characteristic in helical springs

572-913: Is to damp spring oscillations. Shock absorbers use valving of oil and gasses to absorb excess energy from the springs. Spring rates are chosen by the manufacturer based on the weight of the vehicle, loaded and unloaded. Some people use shocks to modify spring rates but this is not the correct use. Along with hysteresis in the tire itself, they damp the energy stored in the motion of the unsprung weight up and down. Effective wheel bounce damping may require tuning shocks to an optimal resistance. Spring -based shock absorbers commonly use coil springs or leaf springs , though torsion bars are used in torsional shocks as well. Ideal springs alone, however, are not shock absorbers, as springs only store and do not dissipate or absorb energy. Vehicles typically employ both hydraulic shock absorbers and springs or torsion bars. In this combination, "shock absorber" refers specifically to

616-476: The Millau Viaduct in southern France are longer at 2,680 m (8,790 ft) and 2,460 m (8,071 ft), respectively. However, as the former has a shorter length of main span (the length of the main span is the most common way to rank cable-stayed bridges, as the size of the main span does often correlate with the height of the towers, and the engineering complexity involved in designing and constructing

660-615: The Peloponnese , which could previously be reached only by ferry or via the isthmus of Corinth in the east. Its width is 28 m (92 ft)—it has two vehicle lanes per direction, an emergency lane and a pedestrian walkway. Its five-span four-pylon cable-stayed portion of length 2,252 m (7,388 ft) is the world's third longest cable-stayed deck; only the decks of the Jiaxing-Shaoxing Sea Bridge in Shaoxing , China and

704-539: The Gabriel Snubber started being fitted in the late 1900s (also the similar Stromberg Anti-Shox). These used a belt coiled inside a device such that it freely wound in under the action of a coiled spring but met friction when drawn out. Gabriel Snubbers were fitted to an 11.9HP Arrol-Johnston car which broke the 6 hour Class B record at Brooklands in late 1912, and the Automator journal noted that this snubber might have

748-411: The Greek companies Hellenic Technodomiki-TEV, J&P -Avax, Athena, Proodeftiki and Pantechniki. The consortium operates the bridge under concession under its ΓΕΦΥΡΑ or ΓαλλοΕλληνικός Φορέας Υπερθαλάσσιας ζεύξης Ρίου-Αντιρίου ( GEFYRA —Greek for "bridge"—or GalloEllinikós Foréas Yperthalássias zéfxis Ríou-Antiríou , French-Greek Carrier of Oversea Connection of Rio–Antirrio) subsidiary. The suspension of

792-437: The action of the auxiliary spring in the unit itself. The first production hydraulic dampers to act on the main leaf spring movement were probably those based on an original concept by Maurice Houdaille patented in 1908 and 1909. These used a lever arm which moved hydraulically damped vanes inside the unit. The main advantage over the friction disk dampers was that it would resist sudden movement but allow slow movement, whereas

836-539: The blue decorative lighting was announced by the company due to the ongoing electricity crisis in Europe but also to be in line with the company's environmental strategy. The bridge's carbon footprint has been reduced by 84.5% from 2015 to 2022. The lead architect was Berdj Mikaelian. Site preparation and dredging began in July 1998, and construction of the massive supporting pylons in 2000. With these complete in 2003, work began on

880-505: The bridge returned to TV in an episode of Richard Hammond's Engineering Connections . In 2015, construction of the bridge was chronicled in the first episode of the Science Channel series Impossible Engineering . On 28 January 2005, six months after the opening of the bridge, one of the cable links of the bridge snapped from the top of the M1 pylon and came crashing down on the deck. Traffic

924-493: The bridge) and as the latter is also supported by bearings at the pylons apart from cable stays, the Rio–Antirrio Bridge deck might be considered the longest cable-stayed "suspended" deck in the world. This bridge is widely considered to be an engineering masterpiece, owing to several solutions applied to span the difficult site. These difficulties include deep water, insecure materials for foundations, seismic activity,

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968-573: The bridge. Protection from the effect of high winds on the decking is provided by the use of aerodynamic spoiler-like fairing and on the cables by the use of spiral Scruton strakes . The bridge received the 2006 Outstanding Structure Award from the International Association for Bridge and Structural Engineering . In 2006 the bridge was featured in an episode of Megastructures on the National Geographic Channel . In 2011

1012-601: The cars or the pedestrians using it. Shock absorber A shock absorber or damper is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the kinetic energy of the shock into another form of energy (typically heat ) which is then dissipated. Most shock absorbers are a form of dashpot (a damper which resists motion via viscous friction). Pneumatic and hydraulic shock absorbers are used in conjunction with cushions and springs. An automobile shock absorber contains spring-loaded check valves and orifices to control

1056-414: The design and first appeared in 1954s. Because the design was patented, no other manufacturer could use it until 1971 when the patent expired. Spool valve dampers are characterized by the use of hollow cylindrical sleeves with machined-in oil passages as opposed to traditional conventional flexible discs or shims. Spool valving can be applied with monotube, twin-tube, or position-sensitive packaging, and

1100-419: The dissipated energy can be stored and used later. In general terms, shock absorbers help cushion vehicles on uneven roads and keep wheels in contact with the ground. In a vehicle, shock absorbers reduce the effect of traveling over rough ground, leading to improved ride quality and vehicle handling . While shock absorbers serve the purpose of limiting excessive suspension movement, their intended main purpose

1144-550: The final cost was €839 million. The bridge was inaugurated on 7 August 2004, a week before the opening of the 2004 Summer Olympics in Athens . Olympic torchbearers were the first to officially cross it. One of them was Otto Rehhagel , the German football coach who won the Euro 2004 Championships for Greece . Another was Costas Laliotis, the former Minister of Public Works during whose term

1188-442: The flow of oil through an internal piston (see below). One design consideration, when designing or choosing a shock absorber, is where that energy will go. In most shock absorbers, energy is converted to heat inside the viscous fluid. In hydraulic cylinders , the hydraulic fluid heats up, while in air cylinders , the hot air is usually exhausted to the atmosphere. In other types of shock absorbers, such as electromagnetic types,

1232-524: The hydraulic fluid through small holes, creating resistance and dissipating energy in the form of heat. This dampens oscillations, reducing further bouncing or wobble of the car. Shock construction requires a balance of features such as piston design, fluid viscosity, and overall size of the unit to ensure performance. As technology developed, other types of shock absorbers emerged, including gas and electric shock absorbers, that provided improved control and flexibility. The design and manufacture of shock absorbers

1276-430: The hydraulic piston that absorbs and dissipates vibration. Now, composite suspension systems are used mainly in 2 wheelers and also leaf springs are made up of composite material in 4 wheelers. Shock absorbers are an important part of car suspension designed to increase comfort, stability and overall safety. The shock absorber, produced with precision and engineering skills, has many important features. The most common type

1320-419: The oil damped in the rebound direction. The Telesco unit was fitted at the rear end of the leaf spring, in place of the rear spring to chassis mount, so that it formed part of the springing system, albeit a hydraulically damped part. This layout was presumably selected as it was easy to apply to existing vehicles, but it meant the hydraulic damping was not applied to the action of the main leaf spring, but only to

1364-409: The piers can move laterally on the sea floor with the gravel bed absorbing the energy. The bridge decking is connected to the pylons using jacks and dampers to absorb movement; too rigid a connection would cause the bridge structure to fail in the event of an earthquake and too much lateral leeway would damage the piers. There is also provision for the gradual widening of the strait over the lifetime of

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1408-414: The piston and via the valve, converting the "shock" energy into heat which must then be dissipated. Variously known as a "gas cell two-tube" or similarly named design, this variation represented a significant advancement over the basic twin-tube form. Its overall structure is very similar to the twin-tube, but a low-pressure charge of nitrogen gas is added to the reserve tube. The result of this alteration

1452-465: The piston starts to occur with greater intensity (i.e., on bumpy sections of roads— the stiffening gives the driver greater control of movement over the vehicle so its range on either side of the comfort zone is called the "control zone"). This advance allowed car designers to make a shock absorber tailored to specific makes and models of vehicles and to take into account a given vehicle's size and weight, its maneuverability, its horsepower, etc. in creating

1496-455: The pressure tube in response to changes in road smoothness. The two pistons also completely separate the shock's fluid and gas components. The mono-tube shock absorber is consistently a much longer overall design than the twin-tubes, making it difficult to mount in passenger cars designed for twin-tube shocks. However, unlike the twin-tubes, the mono-tube shock can be mounted either way— it does not have any directionality. It also does not have

1540-523: The probability of tsunamis , and the expansion of the Gulf of Corinth due to plate tectonics . Charilaos Trikoupis was a 19th-century prime minister of Greece who suggested building a bridge in the current location, but Greece's finances at the time didn't permit its construction. The bridge was planned in the mid-1990s and was built by a French-Greek consortium led by the French group Vinci SA which includes

1584-456: The project had begun. Due to the peculiar conditions of the straits, several unique engineering problems needed to be considered and overcome. The water depth reaches 65 m, the seabed is mostly of loose sediment, the seismic activity and possibility of tectonic movement is significant, and the Gulf of Corinth is expanding at a rate of about 30 mm a year. In addition, the hills on either side create

1628-529: The rotary friction dampers tended to stick and then offer the same resistance regardless of speed of movement. There appears to have been little progress on commercialising the lever arm shock absorbers until after World War I , after which they came into widespread use, for example as standard equipment on the 1927 Ford Model A and manufactured by Houde Engineering Corporation of Buffalo, NY. Most vehicular shock absorbers are either twin-tube or mono-tube types with some variations on these themes. Also known as

1672-526: The spring and vehicle combination bounced with a characteristic frequency, these auxiliary springs were designed with a different period, but were not a solution to the problem that the spring rebound after striking a bump could throw you out of your seat. What was called for was damping that operated on the rebound. Although C.L. Horock came up with a design in 1901 that had hydraulic damping, it worked in one direction only. It does not seem to have gone into production right away, whereas mechanical dampers such as

1716-400: The system is the ability to detect and specifically treat earthquake events. Photography by both professional and amateur photographers or cinematographers is allowed and encouraged by the bridge management without the need for a permit, with the bridge's management often organizing special events inviting professional and amateur photographers and cinematographers to photograph the bridge and

1760-617: The traffic decks. Steel fabrication was undertaken by Cleveland Bridge & Engineering Company . On 21 May 2004 the main stage of construction was completed; only equipment (sidewalks, railings, etc.) and waterproofing remained to be installed. The total cost of the bridge was about €630 million, funded by Greek state funds, the consortium, and loans by the European Investment Bank . It was finished ahead of its original schedule, which had foreseen completion between September and November 2004, and within budget. Other sources suggest

1804-452: The twin-tube form has been the mono-tube shock absorber which was considered a revolutionary advancement when it appeared in the 1950s. As its name implies, the mono-tube shock, which is also a gas-pressurized shock and also comes in a coilover format, consists of only one tube, the pressure tube, though it has two pistons. These pistons are called the working piston and the dividing or floating piston, and they move in relative synchrony inside

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1848-443: Was also fitted to many cars. One of the problems with motor cars was the large variation in sprung weight between lightly loaded and fully loaded, especially for the rear springs. When heavily loaded the springs could bottom out, and apart from fitting rubber 'bump stops', there were attempts to use heavy main springs with auxiliary springs to smooth the ride when lightly loaded, which were often called 'shock absorbers'. Realizing that

1892-443: Was immediately halted. The investigation found that a fire had broken out on the top of the M1 pylon after a lightning strike to one of the cables. The cable was immediately restored and the bridge reopened. A structural health monitoring system was installed during construction on the bridge. Still operating, it provides a 24/7 surveillance of the structure. The system has more than 100 sensors, including: One specific element of

1936-533: Was the reason it was "impossible" to use them as main springs. However the amount of damping provided by leaf spring friction was limited and variable according to the conditions of the springs, and whether wet or dry. It also operated in both directions. Motorcycle front suspension adopted coil sprung Druid forks from about 1906, and similar designs later added Friction disk shock absorber rotary friction dampers, which damped both ways - but they were adjustable (e.g. 1924 Webb forks). These friction disk shock absorber s

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