Aluminium or aluminum is a chemical element with symbol Al and atomic number 13. It is a silvery-white, soft and ductile metal in the boron group. By mass, aluminium makes up about 8% of the Earth's crust; the chief ore of aluminium is bauxite. Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different minerals. Aluminium is remarkable for its low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium and its alloys are vital to the aerospace industry and important in transportation and building industries, such as building facades and window frames; the oxides and sulfates are the most useful compounds of aluminium. Despite its prevalence in the environment, no known form of life uses aluminium salts metabolically, but aluminium is well tolerated by plants and animals; because of these salts' abundance, the potential for a biological role for them is of continuing interest, studies continue.
Of aluminium isotopes, only 27Al is stable. This is consistent with aluminium having an odd atomic number, it is the only aluminium isotope that has existed on Earth in its current form since the creation of the planet. Nearly all the element on Earth is present as this isotope, which makes aluminium a mononuclidic element and means that its standard atomic weight equates to that of the isotope; the standard atomic weight of aluminium is low in comparison with many other metals, which has consequences for the element's properties. All other isotopes of aluminium are radioactive; the most stable of these is 26Al and therefore could not have survived since the formation of the planet. However, 26Al is produced from argon in the atmosphere by spallation caused by cosmic ray protons; the ratio of 26Al to 10Be has been used for radiodating of geological processes over 105 to 106 year time scales, in particular transport, sediment storage, burial times, erosion. Most meteorite scientists believe that the energy released by the decay of 26Al was responsible for the melting and differentiation of some asteroids after their formation 4.55 billion years ago.
The remaining isotopes of aluminium, with mass numbers ranging from 21 to 43, all have half-lives well under an hour. Three metastable states are known, all with half-lives under a minute. An aluminium atom has 13 electrons, arranged in an electron configuration of 3s23p1, with three electrons beyond a stable noble gas configuration. Accordingly, the combined first three ionization energies of aluminium are far lower than the fourth ionization energy alone. Aluminium can easily surrender its three outermost electrons in many chemical reactions; the electronegativity of aluminium is 1.61. A free aluminium atom has a radius of 143 pm. With the three outermost electrons removed, the radius shrinks to 39 pm for a 4-coordinated atom or 53.5 pm for a 6-coordinated atom. At standard temperature and pressure, aluminium atoms form a face-centered cubic crystal system bound by metallic bonding provided by atoms' outermost electrons; this crystal system is shared by some other metals, such as copper. Aluminium metal, when in quantity, is shiny and resembles silver because it preferentially absorbs far ultraviolet radiation while reflecting all visible light so it does not impart any color to reflected light, unlike the reflectance spectra of copper and gold.
Another important characteristic of aluminium is its low density, 2.70 g/cm3. Aluminium is a soft, lightweight and malleable with appearance ranging from silvery to dull gray, depending on the surface roughness, it is nonmagnetic and does not ignite. A fresh film of aluminium serves as a good reflector of visible light and an excellent reflector of medium and far infrared radiation; the yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has stiffness of steel, it is machined, cast and extruded. Aluminium atoms are arranged in a face-centered cubic structure. Aluminium has a stacking-fault energy of 200 mJ/m2. Aluminium is a good thermal and electrical conductor, having 59% the conductivity of copper, both thermal and electrical, while having only 30% of copper's density. Aluminium is capable of superconductivity, with a superconducting critical temperature of 1.2 kelvin and a critical magnetic field of about 100 gauss.
Aluminium is the most common material for the fabrication of superconducting qubits. Aluminium's corrosion resistance can be excellent due to a thin surface layer of aluminium oxide that forms when the bare metal is exposed to air preventing further oxidation, in a process termed passivation; the strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is reduced by aqueous salts in the presence of dissimilar metals. In acidic solutions, aluminium reacts with water to form hydrogen, in alkaline ones to form aluminates—protective passivation under these conditions is negligible; because it is corroded by dissolved chlorides, such as common sodium chloride, household plumbing is never made from aluminium. However, because
A low-floor bus is a bus or trolleybus that has no steps between the ground and the floor of the bus at one or more entrances, low floor for part or all of the passenger cabin. A bus with a partial low floor may be referred to as a low-entry bus in some locations. Low floor refers to a bus deck, accessible from the sidewalk with only a single step with a small height difference, caused by the difference between the bus deck and sidewalk; this is distinct from high-floor, a bus deck design that requires climbing one or more steps to access the interior floor, placed at a higher height. Being low-floor improves the accessibility of the bus for the public the elderly and people with disabilities, including those using wheelchairs and walkers. All are rear-engine, rear-wheel-drive layout with no drive shaft. Low-floor buses are divided into two major types: low-floor buses with a low floor throughout the length of the bus, low-entry buses with step-free access to only a part of the bus, most between the front door and the middle door.
In North America, both types are called low-floor, as the majority of the vehicle has a low floor, without steps at the doors. The main reason for choosing a low-entry configuration is to allow better placement for the powertrain and other technical equipment in the raised floor section, in addition to allowing a more comfortable ride on rough roads; some manufacturers use the initials LF or L in their model designations for low-floor models, in North America buses that are low-floor are also designated LF. In some countries, LE, short for Low Entry, is used by some manufacturers in their model designations for low-entry buses. Most bus manufacturers achieve a low floor height by making rear-engined rear-wheel drive buses with independent front suspension, so that no axle is needed to pass under the floor of the front part of passenger compartment, or a lowered front axle; some full low-floor buses have a lowered rear axle, while the rear axle is not an issue on a low-entry bus. Many low-floor buses, including the Irisbus Citelis, has the engine in a vertical cabinet at the rear of the bus.
Van Hool have a series of "side-engine mid-drive" buses that puts the engine off to one side of the cabin longitudinally between the first and the second axle, to maximize usable cabin space. The same concept was utilized by Volvo on their B9S articulated chassis. For smaller buses, such as midibuses, the low-floor capability is achieved by placing the front wheels ahead of the entrance. One of the last types of buses to gain low-floor accessibility as standard was the minibus, where a similar front-wheel arrangement allows around 12 seats and a wheelchair space to be accommodated in small low-floor minibuses, such as the Optare Alero and Hino Poncho. Accessibility was achieved in paratransit type applications, which use small vehicles with the fitment of special lifts; the inception of small low-floor buses has allowed the development of several accessible demand-responsive transport schemes using standard'off-the-shelf' buses. A disadvantage of the low floor is accommodating the bus's own wheels.
With the low floor, the wheels protrude into the passenger cabin, need to be contained in wheel pockets of waist height, this occupies space which would otherwise be used for seating. To allow space for technical equipment, many low-floor buses have the seats mounted on podiums, making a small step up from the floor, while others are able to mount the seats directly to the floor, avoiding the step. Seating layout for a low-floor bus therefore requires careful design. Low floor configuration is known to have poor side to side dead load distribution within the chassis due to the asymmetrical off-centre placement of driveline components - engine and transmission; as a result, many of such buses require electronically controlled air suspension to compensate the lopsided configuration. Low-floor buses include an area without seating next to at least one of the doors, where wheelchairs, strollers/prams, where allowed bicycles, can be parked; this is sometimes not the only purpose of this area, though, as many operators employ larger standee areas for high occupancy at peak times.
Despite the space existing, operators may insist that only one or two wheelchairs or pushchairs can be accommodated unfolded, due to space/safety concerns. Low floors can be complemented by a hydraulic or pneumatic'kneeling device', which can be used when the bus is not in motion, tilting it or lowering it at the front axle further down to normal curb height. Depending on how close to the curb the bus is parked and wheelchair design, this can allow wheelchair users to board unaided. Though such technology has been available and in use on high-floor buses since the 1970s, it is of significant utility on low-floor vehicles only where it enables less-mobile passengers to board and leave the vehicle without help from others. Many vehicles are equipped with wheel-chair lifts, or ramps which, when combined with a low floor, can provide a nearly level entry. An interesting implementation of the low floor design exists in Australia, where Custom Coaches makes a "Hybrid" variant of its CB60 bodywork.
These buses combine a smaller low floor area with a small underfloor bin for some luggage. Whilst these buses do not provide a full amount of luggage space, they can be used to house more luggage than what can be held inside the bus itself. Another drawback
A single-decker bus or single-decker is a bus that has a single deck for passengers. The use of the term single-decker refers to a standard two-axled rigid bus, in direct contrast to the use of the term double-decker bus, a bus with two passengers decks and a staircase; these types of single-deckers may feature one or more doors, varying internal combustion engine positions. In regions where double-deckers are not common, the term single-decker may lack common usage, as in one sense, all other main types of bus have a single deck; the term may become synonymous with the name transit bus or related terms, which can be applied to double-deckers too. With the exception of regions of major double deck or articulated bus operation urban areas, the single decker is the standard mode of public transport bus travel with low floor features. With their origins in van chassis, minibuses are not considered single-deckers, although modern minibus designs blur this distinction. Midibuses can be regarded as both included with and separate from standard single-deckers, in terms of full size length and vehicle weights, although again design developments have seen this distinction blurred.
Some coach style buses that do not have underfloor luggage space can be termed as single-deckers, with some sharing standard bus chassis designs, such as the Volvo B10M, with a different body style applied. Alexander Dennis Enviro300 Alexander Dennis Enviro350H DAF SB220 Dennis Falcon Dennis Lance/Lance SLF Irisbus Agoraline MAN NL262 MAN NLxx3F Mercedes-Benz Citaro Mercedes-Benz O305 Mercedes-Benz O405 Mercedes-Benz O500M/U Mercedes-Benz OC 500 LE Mercedes-Benz OF-OH Optare Excel Optare Tempo Scania Citywide Scania K UB Scania L113 Scania L94UB Scania N UB Scania N113 Scania N94UB Scania OmniCity VDL SB200 VDL SB250 Volvo B7RLE Volvo B10B Volvo B10BLE Volvo B10M Volvo B12BLE Tram Bus rapid transit List of buses
The Volvo B9R is a rear-engined coach chassis built by Volvo. It can be built with a maximum gross weight of 19,000 kg; the B9R is equipped with a rear-mounted Volvo 9.0-litre 6-cylinder diesel engine under the floor, producing 380 bhp and torque of 1,700 N⋅m. The Plaxton Panther provides 53 seats; the Sunsundegui bodywork provides a 55-seat arrangement. List of buses Volvo Buses B9R official website
A transit bus is a type of bus used on shorter-distance public transport bus services. Several configurations are used, including low-floor buses, high-floor buses, double-decker buses, articulated buses and midibuses; these are distinct from all-seated coaches used for longer distance journeys and smaller minibuses, for more flexible services. A transit bus will have: large and sometimes multiple doors for ease of boarding and exiting minimal or no luggage space bench or bucket seats, with no coachlike head-rests destination blinds / displays such as headsigns or rollsigns or electronic dot matrix/LED signs legal standing-passenger capacity fare taking/verification equipment pull cord or bus stop request buttonModern transit buses are increasingly being equipped with passenger information systems, multimedia, WiFi, USB charging points, entertainment/advertising, passenger comforts such as heating and air-conditioning; some industry members and commentators promote the idea of making the interior of a transit bus as inviting as a private car, recognising the chief competitor to the transit bus in most markets.
As they are used in a public transport role, transit buses can be operated by publicly run transit authorities or municipal bus companies, as well as private transport companies on a public contract or independent basis. Due to the local authority use, transit buses are built to a third-party specification put to the manufacturer by the authority. Early examples of such specification include the Greater Manchester Leyland Atlantean, DMS-class London Daimler Fleetline. New transit buses may be purchased each time a route/area is contracted, such as in the London Buses tendering system; the operating area of a transit bus may be defined as a geographic metropolitan area, with the buses used outside of this area being more varied with buses purchased with other factors in mind. Some regional-size operators for capital cost reasons may use transit buses interchangeably on short urban routes as well as longer rural routes, sometimes up to 2 or 3 hours. Transit bus operators have a selection of'dual-purpose' fitted buses, standard transit buses fitted with coach-type seating, for longer-distance routes.
Sometimes transit buses may be used as express buses on a limited-stopping or non-stop service at peak times, but over the same distance as the regular route. Fare payment is done via Smart card single or multi-ride coupon/ticket cash and is done upon Pre-payment, done at ticket machines located at the bus stops or at other locations, before getting on the bus. Boarding departing both, e.g. after crossing fare zone boundaries in transit, via an attendant or bus conductor Depending on payment systems in different municipalities, there are different rules with regard to which door, front or rear, one must use when boarding/exiting. For rear doors, most buses have doors opened by patron. Most doors on buses use air-assist technology, the driver controlled doors, use air pressure to force them open, patron-operated doors, can push them open, the doors are heavy, so the touch-to-open or push bar mechanism, sends pressurized air to open the doors. Most doors will signify that they are unlocked and open with lights, this gives guide to those who are going up or down the door steps to not trip and fall.
Unlocked or open doors, will trigger a brake locking mechanism on the bus to prevent it from moving while someone could be entering or exiting the bus, when the door is closed, the lock will release, this is implemented on rear doors, not on front doors, since the driver will be paying attention to the front door. Transit buses can be double-decker, rigid or articulated. Selection of type has traditionally been made on a regional as well as operational basis. Depending on local policies, transit buses will usually have two, three or four doors to facilitate rapid boarding and alighting. In cases of low-demand routes, or to navigate small local streets, some models of minibus and small midibuses have been used as transit type buses; the development of the midibus has given many operators a low-cost way of operating a transit bus service, with some midibuses such as the Plaxton SPD Super Pointer Dart resembling full size transit type vehicles. Due to their public transport role, transit buses were the first type of bus to benefit from low-floor technology, in response to a demand for equal access public service provision.
Transit buses are now subject to various disability discrimination acts in several jurisdictions which dictate various design features applied to other vehicles in some cases. Due to the high number of high-profile urban operations, transit buses are at the forefront of bus electrification, with hybrid electric bus, all-electric bus and fuel cell bus development and testing aimed at reducing fuel usage, shift to green electricity and decreasing environmental impact. Developments of the transit bus towards higher capacity bus transport include tram-like vehicles such as guided buses, longer bi-articulated buses and tram-like buses such as the Wright StreetCar as part of Bus Rapid Transit schemes. Fare collection is seeing a shift to off-bus payment, with either the driver or an inspector verifying fare payments. A commuter or express bus service is a fixed-route bus characterized by service predominantly in on
The Volvo 8500 was an aluminium body single-deck city/intercity bus manufactured by Volvo between 2001 and 2011. It was available with medium floor as two-axle, tri-axle and the articulated 8500A; as the low-entry Volvo 8700LE as two-axle, tri-axle and the articulate 8500LEA. From 2005 it was available as the low floor Volvo 7500, which came in a bi-articulated version. In the early years, the 8500LE was available with CNG on the B10BLE chassis. CNG was only available on the 7500. In May 2010 the models received a facelift, the front of its 2011-successor, the 8900; the 7500 found its successor in the 7900. The main markets were Denmark and Sweden, but some were sold in the other Nordic countries; some found their way to Estonia's capital Tallinn. The 7500 never found any buyers outside Sweden if the bi-artics were tested in several cities outside Sweden up through the years. Media related to Volvo 8500 at Wikimedia Commons Media related to Volvo 7500 at Wikimedia Commons
The Volvo B7R is a coach chassis available with a range of bodies. It is promoted as a rear engined lightweight coach chassis, it is intended for tourist and long-distance duties. B7R is manufactured in China, Hungary and Iran for use in regional transport services. B7R is powered by Volvo D7E six-cylinder diesel engine with intercooler; the D7E engine produces 290 hp with 1200 Nm of torque between 1650 r/min. It comes with a retarder incorporated into the gearbox; the retarder slows down the engine. Once the engine slows down, disk brakes take over and bring the vehicle to complete stop in an instant, its frame is a robust steel construction with a flat upper face. A flat upper face simplifies building bus body, it could be built with a maximum length of about 12.5 metres. The B7R is available as complete buses - the Volvo 7350, Volvo 9400 and Volvo 8700; the B7R is the most used deluxe long distance bus in India and is employed by not only the state-owned transport corporations of the state of Karnataka, Rajasthan and Andhra Pradesh but by private operators.
Volvo developed a low-floor variant of B7R, known as the Volvo B7RLE, for intercity and city operations. In Brazil, B7R is produced in Curitiba since 1998; the first B7R in the country was imported from Sweden and operated in Curitiba's public transportation as a Direct Line Bus. In 2012, B7R was renamed to B290R, is used in BRS and BRT applications. In the Philippines, B7R is the basis for the GDW6127HKC and DMMW DM16 manufactured by Autodelta Coach Builders Inc and Del Monte Motor Works, it is similar to the low-end version the B7RLE. Meanwhile in Indonesia, the Volvo B7R only presented from 2003 to 2004, but there are many bus company that use the Volvo B7R, such as PO. Harapan Jaya, PO. Nusantara, etc. In the operation, this bus sometimes sometimes used as a tourist bus. Using the Volvo D7E, this bus has large horsepower, compared with standard Indonesian bus in the Rear Engined Bus, such as Hino RK8JSKA, Hino RG1JS/JN, Mercedes Benz OH 1521, Mercedes Benz OH 1525, but due to the its large power, the maintenance very high, that's why many company that were use the B7R sell the bus into another company and evenly some company change the D7E engine into a Mitsubishi Fuso 6D16 engine or Nissan Diesel FE6B and Hino J08E to reducing operational and maintenance cost.
List of buses Product description in Volvo website