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Recirculating Ball

Recirculating ball

Recirculating Ball , also known as recirculating ball and nut or worm and sector, is a steering mechanism, commonly found in older vehicles. Mercedes-Benz was among the last large automobile manufacturers to use this technology. Today, most steering systems use the rack and pinion system. A worm gear on the end of the steering shaft has a spiral groove filled with ball bearings, all encased in an assembly called the ball nut or steering gear nut. The nut has grooves on the inside to accept the bearings. As the steering wheel is turned, the nut moves up and down along the worm gear. A sector gear transmits the motion of the nut to the steering linkage, causing the vehicle's wheels to turn. Category:Automotive steering technologies

Steering

Steering is the term applied to the collection of components, linkages, etc. which allow for a car or other vehicle to follow a course determined by its driver, except in the case of rail transport in which rail tracks combined together with railroad switches provide the steering function. railroad switch

Introduction

The most conventional steering arrangement is to turn the front wheels using a hand–operated steering wheel which is positioned in front of the driver, via the steering column, which may contain universal joints to allow it to deviate somewhat from a straight line. Other arrangements are sometimes found on different types of vehicles, for example, a tiller or rear–wheel steering. Tracked vehicles such as tanks usually employ differential steering—that is, the tracks are made to move at different speeds or even in opposite directions to bring about a change of course.

Rack and pinion, recirculating ball, worm and sector

Tracked vehicle Many modern cars use rack and pinion steering mechanisms, where the steering wheel turns the pinion gear; the pinion moves the rack, which is a sort of linear gear which meshes with the pinion, from side to side. This motion applies steering torque to the kingpins of the steered wheels via tie rods and a short lever arm called the steering arm. Older designs often use the recirculating ball mechanism, which is still found on trucks and utility vehicles. This is a variation on the older worm and sector design; the steering column turns a large screw (the "worm gear") which meshes with a sector of a gear, causing it to rotate about its axis as the worm gear is turned; an arm attached to the axis of the sector moves the pitman arm, which is connected to the steering linkage and thus steers the wheels. The recirculating ball version of this apparatus reduces the considerable friction by placing large ball bearings between the teeth of the worm and those of the screw; at either end of the apparatus the balls exit from between the two pieces into a channel internal to the box which connects them with the other end of the apparatus, thus they are "recirculated". The rack and pinion design has the advantages of a large degree of feedback and direct steering "feel"; it also does not normally have any backlash, or slack. A disadvantage is that it is not adjustable, so that when it does wear and develop lash, the only cure is replacement. The recirculating ball mechanism has the advantage of a much greater mechanical advantage, so that it was found on larger, heavier vehicles while the rack and pinion was originally limited to smaller and lighter ones; due to the almost universal adoption of power steering, however, this is no longer an important advantage, leading to the increasing use of rack and pinion on newer cars. The recirculating ball design also has a perceptible lash, or "dead spot" on center, where a minute turn of the steering wheel in either direction does not move the steering apparatus; this is easily adjustable via a screw on the end of the steering box to account for wear, but it cannot be entirely eliminated or the mechanism begins to wear very rapidly. This design is still in use in trucks and other large vehicles, where rapidity of steering and direct feel are less important than robustness, maintainability, and mechanical advantage. The much smaller degree of feedback with this design can also sometimes be an advantage; drivers of vehicles with rack and pinion steering can have their thumbs broken when a front wheel hits a bump, causing the steering wheel to kick to one side suddenly (leading to driving instructors telling students to keep their thumbs on the front of the steering wheel, rather than wrapping around the inside of the rim). This effect is even stronger with a heavy vehicle like a truck; recirculating ball steering prevents this degree of feedback, just as it prevents desirable feedback under normal circumstances. The steering linkage connecting the steering box and the wheels usually conforms to a variation of Ackermann steering geometry, to account for the fact that in a turn, the inner wheel is actually traveling a path of smaller radius than the outer wheel, so that the degree of toe suitable for driving in a straight path is not suitable for turns.

Four wheel steering

The system

4 wheel steering (or all wheel steering) is a system employed by some vehicles to increase vehicle stability while maneuvering at high speed, or to decrease turning radius at low speed. In most 4-wheel steering systems, the rear wheels are steered by a computer and actuators. The rear wheels generally cannot turn as far as the front wheels. Sports cars sometimes include 4-wheel steering for stability at high speeds. When performing an abrupt lane change at highway speeds, for example, a car with 4-wheel steering will avoid rear suspension loading common in 2-wheel steering cars. Because the rear wheels steer in the same direction as the front wheels, the car is transitioned more gently into turning. Alternatively, several systems (including Delphi's Quadrasteer, and the system in Honda's Prelude line) allow for the rear wheels to be steered in the opposite direction as the front wheels during low speeds. This allows the vehicle to turn in a significantly smaller radius—sometimes critical for large trucks or vehicles with trailers.

Recent application

Recently, four wheel steering has been offered in trucks with four wheel drive used for towing. All four wheels turn at the same time when you steer. There are controls to switch off the rear steer and options to steer only the rear wheel independent of the front wheels. At slow speeds (e.g. parking)the rear wheels turn opposite of the front wheels, reducing the turning radius by up to twenty-five percent, while at higher speeds both front and rear wheels turn alike (electronically controlled), so that the vehicle may change direction with less yaw, enhancing straight-line stability. The "Snaking effect" experienced during motorway drives while towing a caravan is thus largely nullified. Four wheel steering is popular in large farm vehicles and trucks. General Motors offers Delphi's Quadrasteer in their consumer Silverado/Sierra and Suburban/Yukon. However, only 16,500 vehicles have been sold with this system since its introduction in 2002 through 2004. Due to this low demand, GM will not offer the technology on the 2007 update to these vehicles. Previously, Honda had four wheel steering as an option in their 1988-1994 Prelude, and Mazda also offered four wheel steering on the 626 in 1988. Neither system was very popular, in that whatever improvement they brought to these already excellent-handling vehicles was offset by an unavoidable decrease in sensitivity caused by the increased weight and complexity. Some vehicles now offer a form of "passive" four wheel steering, where the bushings by which the rear suspension attaches to the automobile are designed to compress in a precise direction under the forces of steering, thus slightly altering the rear suspension geometry in such a manner as to enhance stability.

Cars with four wheel steering

- GMC Sierra (2002)
- Honda Prelude (1988)
- Mazda 626 (1988)
- Mitsubishi GTO (also sold as the Mitsubishi 3000GT and the Dodge Stealth)
- Nissan 240SX (SE-R models; available as an option)
- Nissan 300ZX (all Twin-Turbo Z32 models)
- Nissan Silvia (option on all S13 models)
- Nissan Skyline GT-R
- Toyota Aristo (1997)
- Toyota Celica (Option on 5th and 6th generation, 1990-1995)

Articulated steering

Toyota Celica Articulated steering is a system by which a four wheel drive vehicle is split into front and rear halves which are connected by a vertical hinge. The front and rear halves are connected with one or more hydraulic cylinders that change the angle between the halves, including the front and rear axles and wheels, thus steering the vehicle. This system does not use steering arms, king pins, tie rods, etc. as does four wheel steering. If the vertical hinge is placed equidistant between the two axles, it also eliminates the need for a central differential, as both front and rear axles will follow the same path, and thus rotate at the same speed.

Power Steering

Power steering aims to make steering less strenuous for the driver. There are two types of power steering systems--hydraulic and electric/electronic. There is also a hydraulic-electric hybrid system possible.

Safety

For safety reasons all modern cars feature a collapsible steering column which will collapse in the event of a heavy frontal impact to avoid excessive injuries to the driver. This safety feature first appeared on cars built by General Motors after an extensive and very public lobbying campaign enacted by Ralph Nader.

Cycles

Steering is crucial to the stability of bicycles and motorcycles (see article on bicycle).

Railroad vehicles

Railroad wheels have fixed axles and tyres with a greater inner than outer radius. Any movement off center automatically corrects itself because the wheel resting on a greater radius travels faster. This effect also allows for cornering. Wheels also have flanges to prevent derailing.

External links

- [http://auto.howstuffworks.com/steering.htm How Car Steering Works (HowStuffWorks.com)] Category:Automotive steering technologies ja:ステアリング

Automobile

An automobile is a wheeled vehicle that carries its own motor. Different types of automobiles include cars, buses, trucks, jeeps, and vans, with cars being the most popular. The term is derived from Greek 'autos' (self) and Latin 'movére' (move), referring to the fact that it 'moves by itself'. Earlier terms for automobile include 'horseless carriage' and 'motor car'. An automobile has seats for the driver and, almost without exception, one or more passengers. It is the main source of transportation across the world. In 2005 there are 500 million cars worldwide (0.07 per capita), of which 220 million are located in the United States (0.75 per capita).

History

:Main article: History of the automobile Steam-powered self-propelled vehicles were devised in the late 18th century. The first self-propelled car was built by Nicolas-Joseph Cugnot in 1769—it could attain speeds of up to 6 km/h. In 1771 he designed another steam-driven engine, which ran so fast that it rammed into a wall, producing the world’s first car accident. In 1807 Francois Isaac de Rivaz designed the first internal combustion engine (sometimes abbreviated "ICE" today). He subsequently used it to develop the world’s first vehicle to run on such an engine, one that used a mixture of hydrogen and oxygen to generate energy. This spawned the birth of a number of designs based on the internal combustion engine in the early nineteenth century with little or no degree of commercial success. In 1860 thereafter, Jean Joseph Etienne Lenoir built the first successful two-stroke gas driven engine. In 1862 he again built an experimental vehicle driven by his gas-engine, which ran at a speed of 3 km/h. These cars became popular and by 1865 could be frequently seen on the roads. The first American automobiles with gasoline-powered internal combustion engines were completed in 1877 by George Baldwin Selden of Rochester, New York, who applied for a patent on the automobile in 1879. Selden received his patent and later sued the Ford Motor company for infringing his patent. Henry Ford was notoriously against the American patent system, and Selden's case against Ford went all the way to the Supreme Court, who ruled that Ford had to pay a penalty to Selden, but could continue manufacturing automobiles, because the technology had changed quite a bit by that time. Later on, in Germany, automobiles were developed almost simultaneously in 1886 by German inventors working independently: Carl Benz on 3 July 1886 in Mannheim, Gottlieb Daimler and Wilhelm Maybach in Stuttgart (also inventors of the first motor bike) and in 1888/89 German - Austrian inventor Siegfried Marcus in Vienna. Meanwhile, notable advances in steam power evolved in Birmingham, England by the Lunar Society. It was here that the term horsepower was first used. It was in Birmingham also that the first British four wheel petrol-driven automobiles were built in 1895 by Frederick William Lanchester who also patented the disc brake in the city. Electric vehicles were produced by a small number of manufacturers.

Innovation

Electric vehicle from the 1950s]] The first automobile patent in the United States was granted to Oliver Evans in 1789; in 1804 Evans demonstrated his first successful self-propelled vehicle, which not only was the first automobile in the USA but was also the first amphibious vehicle, as his steam-powered vehicle was able to travel on wheels on land and via a paddle wheel in the water. On November 5, 1895, George B. Selden was granted a United States patent for a two-stroke automobile engine (). This patent did more to hinder than encourage development of autos in the USA. A major breakthrough came with the historic drive of Bertha Benz in 1888. Steam, electric, and gasoline powered autos competed for decades, with gasoline internal combustion engines achieving dominance in the 1910s. 1910s] The large scale, production-line manufacturing of affordable automobiles was debuted by Oldsmobile in 1902, then greatly expanded by Henry Ford in the 1910s. Early automobiles were often referred to as 'horseless carriages', and did not stray far from the design of their predecessor. Through the period from 1900 to the mid 1920s, development of automotive technology was rapid, due in part to a huge (hundreds) number of small manufacturers all competing to gain the world's attention. Key developments included electric ignition and the electric self-starter (both by Charles Kettering, for the Cadillac Motor Company in 1910-1911), independent suspension, and four-wheel brakes. By the 1930s, most of the technology used in automobiles had been invented, although it was often re-invented again at a later date and credited to someone else. For example, front-wheel drive was re-introduced by Andre Citroën with the launch of the Traction Avant in 1934, though it appeared several years earlier in road cars made by Alvis and Cord, and in racing cars by Miller (and may have appeared as early as 1897). After 1930, the number of auto manufacturers declined sharply as the industry consolidated and matured. Since 1960, the number of manufacturers has remained virtually constant, and innovation slowed. For the most part, "new" automotive technology was a refinement on earlier work, though these refinements were sometimes so extensive as to render the original work nearly unrecognizable. The chief exception to this was electronic engine management, which entered into wide use in the 1960s, when electronic parts became cheap enough to be mass-produced and rugged enough to handle the harsh environment of an automobile. Developed by Bosch, these electronic systems have enabled automobiles to drastically reduce exhaust emissions while increasing efficiency and power.

Model changeover and design change

exhaust Cars are not merely continually perfected mechanical contrivances; since the 1920s nearly all have been mass-produced to meet a market, so marketing plans and manufacture to meet them have often dominated automobile design. It was Alfred P. Sloan who established the idea of different makes of cars produced by one firm, so that buyers could "move up" as their fortunes improved. The makes shared parts with one another so that the larger production volume resulted in lower costs for each price range. For example, in the 1950s, Chevrolet shared hood, doors, roof, and windows with Pontiac; the LaSalle of the 1930s, sold by Cadillac, used the cheaper mechanical parts made by the Oldsmobile division. He also conceived of the notion of the yearly model change-over, which became a three-year cycle. In the second year of the cycle, the superficial appearance of the cars changed incidentally; for the third, major changes took place, e.g., the fender dies for the 1957 Chevrolet had to be modified to produce thin, pointed fins and squarish headlamp housings. In the next cycle, the doors, roof, trunk, and often the suspension would have to be redesigned. Factories and the yearly work schedule had to be specialized to accommodate these changeovers. Such a patterns became dominant for the Big Three automakers in the US, though European firms neither amalgamated nor could afford the changeover. After the 1400s, when American firms tackled the technical problems of high-compression V8, automatic transmissions, and air conditioners, investment shifted to meeting the market for non-technical matters. This was criticized as "planned obsolescence," although by this it was meant that the car would simply be made to go out of style rather than really being technically surpassed. For example, only those few American cars of the 1960s with front-wheel drive or a rear engine had a fully independent rear suspension because the Hotchkiss drive was cheaper, and people were used to it. Such malinvestment left American firms unprepared for the Oil Crisis of the 1970s and the rise of imported luxury cars in the 1980s.

Regulation

In almost every nation, laws have been enacted governing the operation of motor vehicles. Most of this legislation, including limits on allowable speed and other rules of the road, are designed to ensure the smooth flow of traffic and simultaneously protect the safety of vehicle occupants, cyclists, and pedestrians. In 1965, in the U.S. state of California, state legislation was introduced to regulate exhaust emissions, the first such legislation in the world. Answering this new interest in environmental and public safety issues, the Department of Transportation (DOT) and the Environmental Protection Agency (EPA) both introduced legislation in 1968 which substantially altered the course of automotive development. Since the US market was the largest in the world (and California the largest market in the US), manufacturers worldwide were forced to adapt. For the first time, safety devices were mandatory, as were controls on harmful emissions. Prior to this legislation, even seat belts were considered extra-cost options by many manufacturers. Other countries followed by introducing their own safety and environmental legislation. In time, meeting regulations became the main challenge for the engineers designing new cars. In the decade from 1975 to 1985, the world's manufacturers struggled to meet the new regulations, some producing substandard cars with reduced reliability as a result. However, by the end of this period, everyone had learned how to handle the newly regulated environment. The manufacturers discovered that safety and environmentalism sold cars, and some began introducing environmental and safety advances on their own initiative.

Environmental improvements

The automobile was hailed as an environmental improvement over horses when it was first introduced. Before its introduction, in New York City, over 10,000 tons of manure had to be removed from the streets daily. Among the first environmental advances are the so-called alternative fuels for the internal combustion engine, which have been around for many years. Early in automotive history, before gasoline was widely available at corner pumps, cars ran on many fuels, including kerosene (paraffin) and coal gas. Alcohol fuels were used in racing cars before and just after World War II. Today, methanol and ethanol are used as petrol extenders in some countries, notably in Australia and the United States. In countries with warmer climates, such as Brazil, alcohol derived from sugar cane is often used as a substitute fuel. In many countries, plentiful supplies of natural gas have seen methane sold as compressed natural gas (CNG) and propane sold as liquified petroleum gas (LPG) alongside petrol and diesel fuels since the 1970s. While a standard automotive engine will run on these fuels with very low exhaust emissions, there are some performance differences, notably a loss of power due to the lower energy content of the alternative fuels. The need to equip filling stations and vehicles with pressurized vessels to hold these gaseous fuels and more stringent safety inspections, means that they are only economical when used for a long distance, or if there are installation incentives. They are most economical where petrol has high taxes and the alternative fuels do not.

Alternative fuels and batteries

With heavy taxes on fuel, particularly in Europe and tightening environmental laws, particularly in California, and the possibility of further restrictions on greenhouse gas emissions, work on alternative power systems for vehicles continues. Diesel-powered cars can run with little or no modification on 100% pure biodiesel, a fuel that can be made from vegetable oils. Many cars that currently use gasoline can run on ethanol, a fuel made from plant sugars. Most cars that are designed to run on gasoline are capable of running with 15% ethanol mixed in, and with a small amout of redesign, gasoline-powered vehicles can run on ethanol concentrations as high as 85%. All petrol fueled cars can run on LPG. There has been some concern that the ethanol-gasoline mixtures prematurely wear down seals and gaskets. Further, the use of higher levels of alcohol require that the automobile carry/use twice as much. Therefore, if your vehicle is capable of 300 miles on a 15-gallon tank, the efficiency is reduced to approximately 150 miles. Of course, certain measures are available to increase this efficiency, such as different camshaft configurations, altering the timing/spark output of the ignition, or simply, using a larger fuel tank. In the United States, alcohol fuel was produced in corn-alcohol stills until Prohibition criminalized the production of alcohol in 1919. Brazil is the only country which produces ethanol-running cars, since the late 1970s. Attempts at building viable battery-powered electric vehicles continued throughout the 1990s (notably General Motors with the EV1), but cost, speed and inadequate driving range made them uneconomical. Battery powered cars have used lead-acid batteries which are greatly damaged in their recharge capacity if discharged beyond 75% on a regular basis and NiMH batteries. Current research and development is centered on "hybrid" vehicles that use both electric power and internal combustion. The first hybrid vehicle available for sale in the USA was the Honda Insight. As of 2005, The car is still in production and achieves around 60 mpg. Other R&D efforts in alternative forms of power focus on developing fuel cells, alternative forms of combustion such as GDI and HCCI, and even the stored energy of compressed air (see Air Engine).

Safety

Automobiles were a significant improvement in safety on a per passenger mile basis, over the horse based travel that they replaced. Millions have been able to reach medical care much more quickly when transported by ambulance. Accidents seem as old as automobile vehicles themselves. Joseph Cugnot crashed his steam-powered "Fardier" against a wall in 1770. The first recorded automobile fatality was Bridget Driscoll on August 17, 1896 in London and the first in the United States was Henry Bliss on September 13, 1899 in New York City. Worldwide, every year more than a million people are killed and about 50 million people are wounded in collisions (according to WHO estimates). Cars also cause innumerable injuries and deaths among millions of animals (see roadkill). Major factors in accidents include the use of alcohol or other drugs, inattentiveness, the use of handheld mobile phones, tiredness, road hazards such as snow, potholes, and animals, and recklessness. Special safety features have been built into cars for years, some for the safety of car's occupants only, some for the safety of others. Cars have two basic safety problems: They have human drivers who make mistakes, and the wheels lose traction near a half gravity of deceleration. Automated control has been seriously proposed and successfully prototyped. Shoulder-belted passengers could tolerate a 32G emergency stop (reducing the safe intervehicle gap 64-fold) if high-speed roads incorporated a steel rail for emergency braking. Both safety modifications of the roadway are thought to be too expensive by most funding authorities, although these modifications could dramatically increase the number of vehicles that could safely use a high-speed highway. Early safety research focused on increasing the reliability of brakes and reducing the flammability of fuel systems. For example, modern engine compartments are open at the bottom so that fuel vapors, which are heavier than air, vent to the open air. Brakes are hydraulic so that failures are slow leaks, rather than abrupt cable breaks. Systematic research on crash safety started in 1958 at Ford Motor Company. Since then, most research has focused on absorbing external crash energy with crushable panels and reducing the motion of human bodies in the passenger compartment. There are standard tests for safety in new automobiles, like the EuroNCAP and the [http://www.nhtsa.dot.gov/cars/testing/ncap/ US NCAP] tests. There are also tests run by organizations such as [http://www.hwysafety.org/ IIHS] and backed by the insurance industry. Despite technological advances, there is still significant loss of life from car accidents: About 40,000 people die every year in the US, with similar trends in Europe. This figure increases annually in step with rising population and increasing travel, but the rate per capita and per mile travelled decreases steadily. The death toll is expected to nearly double worldwide by 2020. A much higher number of accidents result in injury or permanent disability.

Future of the car

There will always be a strong demand for the door-to-door, on-demand service but there are likely to be radical changes in the cars of the future.

Major possible subsystems

- engine
- carburetor or fuel injection
- fuel pump
- engine configuration: Wankel or reciprocating (V, inline, flat).
- engine management systems
- exhaust system
- ignition system
- self starter
- emissions control devices
- turbochargers and superchargers
- front engine
- rear engine
- mid engine
- Ancillary power - mechanical, electrical, hydraulic, vacuum, air
- drivetrain
- transmission (gearbox)
- manual transmission
- semi-automatic transmission
- fully-automatic transmission
- Layout
- FF layout
- FR layout
- MR layout
- RR layout
- Drive Wheels
- 2 wheel drive
- 4 wheel drive
- Front wheel drive
- Rear wheel drive
- All wheel drive
- differential
- limited slip differential
- axle
- Live axle
- brakes
- disc brakes
- drum brakes
- anti-lock braking systems (ABS)
- wheels and tires
- custom wheels
- steering
- rack and pinion
- Ackermann steering geometry
- Caster angle
- Camber angle
- Kingpin
- suspension
- MacPherson strut
- wishbone
- double wishbone
- multi-link
- torsion beam
- semi-trailing arm
- axle
- body
- crumple zones
- monocoque (or unibody) construction
- suicide doors
- spoiler
- interior equipment
- passive safety
- seat belts
- airbags
- child safety locks
- dashboard
- shifter for selecting gear ratios
- ancillary equipment such as stereos, air conditioning, cruise control, car phones, positioning systems, cup holders, etc.
- exterior equipment
- windows
- Power window
- windshield
- Daytime running lamps

External links

- [http://www.dmv.org/ Department of Motor Vehicles]
- [http://www.automotivehistory.net/ A brief history of the automotive form]
- [http://www.autoweek.com/ Autoweek.com]
- [http://www.detnews.com/autosinsider/index.htm Auto Insider]
- [http://www.edmunds.com/ Edmunds.com]
- [http://www.kbb.com/ Kelley Blue Book]
- [http://www.hwysafety.org/ Insurance Institute for Highway Safety]
- [http://nhtsa.gov/ NHTSA.gov]
- [http://www.naftc.wvu.edu/ Alternative Fuel Vehicle Training]
- [http://supercarnews.com/ Car Images and Info]
- [http://www.netcarshow.com/ NetCarShow.com] - Archive of car pictures
- ko:자동차 ms:Kereta ja:自動車 simple:Car th:รถยนต์

Rack and pinion

A rack and pinion is a pair of gears which convert rotational motion into linear motion. The circular pinion engages teeth on a flat bar - the rack. Rotational motion applied to the pinion will cause the rack to move to the side, up to the limit of its travel. The rack and pinion arrangement is commonly found in the steering mechanisms of cars or other wheeled, steered vehicles. This arrangement provides a lesser mechanical advantage than other mechanisms such as recirculating ball, but much less backlash and greater feedback, or steering "feel". For rack and pinion railways see Cog railway. Category:Automotive steering technologies Category:Auto parts Category:Gears

Shaft

A shaft can be
- an aggressive remark directed at a person like a missile and intended to have a telling effect; "his parting shot was `drop dead'"; "she threw shafts of sarcasm"; "she takes a dig at me every chance she gets"
- slang, meaning to receive unfair treatment; "Bill got shafted"
- a hole in the earth typically used for mineral extraction, such as mining. Mineshafts will normally be vertical, man-made structures. (See also pitch (vertical space)).
- a long cylindrical piece of metal, typically found in motors, machines etc.; axles or driveshafts, for example.
- the long cylindrical section of an architectural column between the base and the capital.
- a vertical space inside a building used to conduct pipes, conduits, or cables between floors. Elevators also travel in shafts; see Elevator shaft. See also Shafting.
- a modern vulgarism meaning penis.
- a weapon in the Quake video game series.
- a term that refers to the height of a boot.
- Shaft can also refer to
- a 1971 film; see Shaft
- and its 2000 remake, Shaft
- a superhero character in Youngblood comics created by Rob Liefeld
- an anime production company; see SHAFT

Ball bearing

plated steel balls]] A ball bearing is a common type of rolling-element bearing, a kind of bearing. The term ball bearing sometimes means a bearing assembly which uses spherical bearings as the rolling elements. It also means an individual ball for a bearing assembly. The remainder of this entry uses the term ball for the individual component and ball bearing or just 'bearing' for the assembly. Ball bearings typically support both axial and radial loads and can tolerate some misalignment of the inner and outer races. Also, balls are relatively easy to make cheaply compared to other kinds of rolling elements. Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings.

Common Designs

There are several common designs of ball bearings, each offering various tradeoffs.
- A radial ball bearing uses inner and outer races that are shaped so a radial load passes radially through the bearing. Most radial designs also support modest axial loads.
- An angular contact ball bearing uses offset races. An angular load passes in a straight line through the bearing, whereas a radial load takes an oblique path that tends to separate the races axially. So the angle of contact on the inner race is the same as that on the outer race. Angular contact bearings allow 'combined loads' (loading in both the radial and axial direcetions) and the contact angle of the bearing should be matched to the relative porportions of each. The larger the contact angle, the higher the axial load supported, but the lower the radial load. In high speed applications, such as turbines, jet engines, dentistry equipment, the centrifugal forces generated by the balls will change the contact angle at the inner and outer race. Ceramics such as silicon nitride are now regularly used in such applications due to its low density (40% of steel - and so significantly reduced centrifugal force), its ability to function is high temperature environments, and the fact that it tends to wear in a similar way to bearing steel (rather than cracking or shattering like glass or porcelain).
- An axial ball bearing uses side-by-side races. An axial load is transmitted directly through the bearing, while a radial load is poorly-supported, tends to separate the races, and anything other than a small radial load is likely to damage the bearing.
- A deep-groove radial bearing is one in which the race dimensions are close to the dimensions of the balls that run in it. Deep-groove bearings have higher load ratings for their size than shallow-groove bearings, but are also less tolerant of misalignment of the inner and outer races. A misaligned shallow-groove bearing may support a larger load than a similar deep-groove bearing with similar misalignment.
- A slot fill radial bearing is one in which the inner and outer races are notched so that when they are aligned, balls can be slipped in the slot in order to fill the bearing. A slot-fill bearing has the advantage that the entire groove is filled with balls, called a full complement. A slot-fill bearing has the disadvantages that it handles axial loads poorly, and the notches weaken the races. Note that an angular contact bearing can be disassembled axially and so can easily be filled with a full complement.
- A Conrad bearing is assembled by placing the inner and outer races radially offset, so the races touch at one point and have a large gap on the radially opposite side. The bearing is then filled by placing balls in to the large gap, then distributing them around the bearing assembly. The act of distributing the balls causes the inner and outer races to become concentric. If the balls were left free, the balls could resume their offset locations and the bearing could disassemble itself. Thus, a cage is inserted to hold the balls in their distributed positions. The cage supports no bearing load; it serves to keep the balls located. Conrad bearings have the advantage that they take both radial and axial loads, but the disadvantage they cannot be filled to a full complement and thus have reduced load-carrying capacity compared to a full-complement bearing. The Conrad bearing is named for its inventor, Robert Conrad, who got British patent 12,206 in 1903 and U.S. patent 822,723 in 1906.
- The outer race may be split axially or radially, or a hole drilled in it for filling. These approaches allow a full complement to be used, but also limit the orientation of loads or the amount of misalignment the bearing can tolerate. Thus, these designs find much less use.
- Most ball bearings are single row designs. Some double row designs are available but they need better alignment than single-row bearings. Probably the most familiar industrial ball bearing is the deep-groove Conrad style. Most bicycles use angular-contact bearings in the headsets because the forces on these bearings are in both the radial and axial direction. The angular-contact bearing is able to withstand such a combined load, as well as small misalignments which often occurs, due to the flexibility of the front fork. Caged bearings typically have fewer balls than a full complement, and thus have reduced load capacity. However, cages keep balls from scuffing directly against each other and so can reduce the drag of a loaded bearing. Category:bearings

The Black Crowes

The Black Crowes é uma banda de rock americana de Atlanta, Georgia. O grupo começou em 1985 e vendeu até hoje mais de 15 milhões de álbuns. A banda ocupa a posição #92 na lista dos 100 Maiores Artistas de Hard Rock da VH1. A banda é uma das mais eficazes máquinas no campo das guitarrices e psicodelias em geral. O grupo mostra nos seis discos lançados e ao vivo que é muito mais do que uma cópia de The Rolling Stones ou The Faces - a quem são freqüentemente associados. Com integrantes não muito mais velhos que suas próprias tendências, a banda tem a aparência tipicamente roqueira: cabelos longos, roupas aveludadas, coletes e físicos impossivelmente fracos. Além disso, aquele tradicional som "blueseiro" e alcoólatra. O vocalista Chris Robinson é um dos mais intrigantes showmen do rock atual. Com voz de Rod Stewart, trejeitos de Mick Jagger e visual glam inspirado em David Bowie, ele faz a linha de frente do Black Crowes com seu irmão Rich Robinson, que fundiu em sua guitarra a magreza de Keith Richards e a sensação rítmica suja de Ron Wood. Stan, o pai dos irmãos Robinson, foi cantor e teve até uma música pop famosa chamada "Boom-a-Dip-Dip". Ele sempre desencorajou os filhos a se tornarem músicos profissionais, mas por volta de 1984 eles já estavam formando a banda Mr. Crowe’s Garden (nome do conto de fadas preferido dos Robinson), que logo passou a se chamar simplesmente Black Crowes e culminou com Chris abandonando a faculdade. Black Crowes pode ser definido como a fusão de Rolling Stones com Lynryd Skynyrd, misturando um blues pesado com rock básico. Com essa mescla convocaram o baixista Johnny Colt, o guitarrista Jeff Cease e o baterista Steve Gorman para gravarem o primeiro disco. Lançado em 1990, Shake Your Moneymaker é uma forte investida na mistura rock/blues e a estréia é surpreendente. O disco vendeu mais de 4 milhões de cópias e com ele a banda foi eleita revelação do ano pelos críticos americanos. "Twice As Hard", "Jealous Again" e "Hard To Handle", de Otis Redding são algumas das pérolas do álbum, sem contar a lindíssima balada "She Talks To Angels", que sozinha vale o disco. Em março de 1991, os Black Crowes foram convidados para abrir shows do ZZ Top. Durante a tour, Chris Robinson fez algumas observações sarcásticas sobre comercialismo e foram expulsos após expressarem suas opiniões sobre manter bandas de rock livres da incorporação de patrocinadores, já que a marca de cerveja que estava realizando a excursão, obviamente, não gostou nem um pouco da idéia. Dois meses depois a banda sairia em turnê própria, abrindo seus shows com um ato da ópera Maggie’s Dream. Como se pode perceber, Chris Robinson não é uma pessoa fácil, e na mesma época foi preso por agressão e por perturbar a paz depois de discutir com uma cliente de uma loja de conveniência em Denver. Passou três meses brigando na Justiça, onde conseguiu o direito de cumprir 6 meses de trabalho comunitário em liberdade após desembolsar 530 dólares de multa. Chris desmoronou em desnutrição e esgotamento durante a passagem da banda pelo Reino Unido, onde estava sendo altamente requisitada. Mal se recuperou dos problemas de saúde e o vocalista levou sua banda ao Monsters Of Rock em Moscou, na Rússia. Jeff Cease é então substituído pelo guitarrista Marc Ford, vindo da banda Burning Tree, de Los Angeles. O Crowes apoia a retórica a favor da maconha, tocando no Great Atlanta Pot Festival, organizado pela National Organization to Reform Marijuana Laws, algo como Organização Nacional Para Reforma das Leis da Maconha. No segundo trimestre de 1992 é lançado o segundo álbum, chamado The Southern Harmony And Musical Companion. O sucesso permite experimentações e a banda mergulha no psicodelismo. Músicas como "Remedy", "Thorn In My Pride", "Sometimes Salvation" e a inspiradíssima versão de "Time Will Tell", de Bob Marley, levam o álbum ao topo da parada americana e ao segundo lugar da parada inglesa. Com o sucesso, a banda se estabeleceu como uma atração obrigatória nos concertos populares de verão nos EUA. Ainda em 1992 a banda adicionou o tecladista Eddie Hersch ao grupo como um integrante permanente. Em fevereiro de 1993, um show com entrada gratuita em Houston ocasionou uma verdadeira invasão ao local da apresentação, fazendo com que a segurança da própria banda estivesse ameaçada. Porém, o êxtase dos fãs e o bom trabalho da polícia fizeram do show um fato marcante na história da banda. Em março do mesmo ano a banda encerraria um show em Louisville, Kentucky, após tocar apenas uma música, devido a problemas no backstage entre os roadies e oficiais da divisão de narcóticos do estado. Neste mesmo dia, o chefe de segurança e o supervisor comercial da banda foram presos após agredirem os policiais. A fórmula dos álbuns anteriores é levada às últimas conseqüências no terceiro disco Amorica, lançado em 1994. Eles carregam no experimental em "Gone” e “A Conspiracy", na melodia em "Wiser Time" e no groove em "P.25 London". Amorica chega ao top 10 da parada americana, mas a marca principal do disco foi a capa, que mostra o close de uma mulher de biquíni, que tem parte de seus pêlos púbicos expostos. A ilustração do biquíni possui desenhos que remetem a bandeira americana, por isso algumas tiragens tiveram sua capa alterada devido a atritos com autoridades governamentais. "Eu sei que isso é o que nós queremos ser e onde queremos viver, por isso estamos presos na América", explica Chris Robinson sobre a inspiração do título de Amorica. Durante a turnê deste disco, a banda vai ao Brasil e faz um show com longas jam sessions. Em julho de 1996 sai o quarto álbum da banda, Three Snakes And One Charm, com Eddie Harsch tocando teclados. Problemas de relacionamento pessoal e musical entre os irmãos Robinson quase decretam o fim. Muita loucura e a falta de uma direção musical resultam em um trabalho irregular. Destaques para "Blackberry", "Good Friday" e "Evil Eye". Em agosto de 1997, Marc Ford é despedido depois de cinco anos como guitarrista da banda. Poucos meses depois, o baixista Johnny Colt também sai, entrando em seu lugar Sven Pipien, ex-Mary My Hope. Após assinarem contrato com a Columbia Records, é lançado em 1998 o quinto álbum, By Your Side. Produzido por Kevin Shirley, um dos colaboradores do Aerosmith, o disco é uma espécie de retorno às origens. Musicalmente, os irmãos Robinson nunca estiveram tão entrosados. O rockão "Go Faster", o já sucesso "Kickin'My Heart Around" e a porrada "HorseHead" fazem deste um álbum coeso. Saem em turnê durante seis semanas, a qual foi chamada de "Sho' Nuff" e no mesmo ano lançam uma box set com os cinco discos da banda remasterizados chamada SHO'NUFF - The Complete Black Crowes, cada um com músicas inéditas ou versões alternativas, mais um CD extra gravado ao vivo durante a tour. No mesmo ano a banda une-se a Jimmy Page para uma série de apresentações nos EUA e Inglaterra. Em 2000 lançam o álbum Jimmy Page and the Black Crowes Live at the Greek, que consiste principalmente nos padrões Led Zeppelin de se fazer música. Versões de clássicos zeppelianos com o toque especial dos irmãos Robinson fazem deste um disco empolgante do começo ao fim, com destaque para a alucinante versão de "Ten Years Gone". Esse álbum arrepiou alguns conservadores no mundo da indústria fonográfica, por sua distribuição inicial ter sido feita online. O excelente guitarrista Audley Freed, ex-Cry Of Love, também fez parte da formação da banda que acompanhou a turnê com Jimmy Page. Em 8 de Maio de de 2001 a banda lança seu sexto álbum de estúdio Lions,, que inclue músicas como "Miracle To Me", "Losing My Mind", "Soul Singin", "Cosmic Man" e etc. Mas em 2002 o Black Crowes anunciam um "hiato por tempo indeterminado". Muitos decretaram que esse era o fim da banda, ocasionado por problemas de relacionamento entre os membros e principalmente devido ao casamento de Chris Robinson com a atriz Kate Hudson . Durante este período, Chris lançou dois discos solo: New Earth Mud (2003) e This Magnificent Distance (2004). Seu irmão, Rich Robinson, também lança um disco próprio: Paper (2004). Após mais de 3 anos, em 2005, o Black Crowes, retornou aos palcos num clima eufórico e intimista. O primeiro show, no dia 14 de Março de 2005, ocorreu no pequeno bar “Staircase”, na cidade de Pittson-PA. O curioso é que nesses shows em bares, os Black Crowes estavam com outro nome. Mr.Crowe’s Garden, que era o nome da banda antes do estrelato, foi o codinome do grupo para despistar a grande imprensa. Sendo assim, somente os verdadeiros fãs atentos iriam aos concertos. Esses shows, que também serviram para aquecer as turbinas da banda, duraram uma semana. O tão aguardado show oficial de retorno dos Black Crowes se deu no dia 22 de Março de 2005, em Nova York, no Hammerstein Ballroom. Ingressos esgotados e uma noite com graneds clássicos da banda. Com exceção do baterista Steve Gorman, que anda parado com a música, os Black Crowes voltaram com Chris Robinson (vocal), Rich Robinson (guitarra e voz), Sven Pipien (baixo), Ed Harsch (teclado), Bill Dobrow (bateria), além do grande guitarrista Marc Ford, que após a saída dos Crowes em 1997, andou tocando com Gov’t Mule e Ben Harper. Steve Gorman retornou a banda na segunda metade de 2005 e atualmente os Black Crowes estão em turnê com Tom Petty and the Heartbreakers.

Discografia

- Shake Your Money Maker (1990)
- The Southern Harmony and Musical Companion (1992)
- Amorica (1994)
- Three Snakes & One Charm (1996)
- Sho' Nuff Box set com faixas bônus (1998)
- By Your Side (1999)
- Greatest Hits 1990-1999: A Tribute to a Work in Progress (2000)
- Live at the Greek (2000) (comJimmy Page)
- Lions (2001)
- Live (2002)

Discografia Comentada

- Shake Your Money Maker (1990) Esse primeiro álbum é uma forte investida na mistura rock/blues e a estréia é surpreendente. O disco vendeu mais de 4 milhões de cópias e com ele a banda foi eleita revelação do ano pelos críticos americanos. "Twice As Hard", "Jealous Again", "She Talks To Angels" e "Hard To Handle", de Otis Redding são alguns dos sucessos do disco.
- The Southern Harmony and Musical Companion (1992) No segundo trimestre de 1992 é lançado o segundo álbum, chamado The Southern Harmony And Musical Companion. O sucesso permite experimentações e a banda mergulha no psicodelismo. Músicas como "Remedy", "Thorn In My Pride", "Sometimes Salvation" e a inspiradíssima versão de "Time Will Tell", de Bob Marley, levam o álbum ao topo da parada americana e ao segundo lugar da parada inglesa.
- Amorica (1994) A fórmula dos álbuns anteriores é levada às últimas conseqüências no terceiro disco Amorica, lançado em 1994. Eles carregam no experimental em "Gone” e “A Conspiracy", na melodia em "Wiser Time" e no groove em "P.25 London". Amorica chega ao top 10 da parada americana, mas a marca principal do disco foi a capa, que mostra o close de uma mulher de biquíni, que tem parte de seus pêlos púbicos expostos. A ilustração do biquíni possui desenhos que remetem a bandeira americana, por isso algumas tiragens tiveram sua capa alterada devido a atritos com autoridades governamentais.
- Three Snakes & One Charm (1996) Em julho de 1996 sai o quarto álbum da banda, Three Snakes And One Charm, com Eddie Harsch tocando teclados. Problemas de relacionamento pessoal e musical entre os irmãos Robinson quase decretam o fim. Muita loucura e a falta de uma direção musical resultam em um trabalho irregular. Destaques para "Blackberry", "Good Friday" e "Evil Eye".
- Sho' Nuff Box set com faixas bônus (1998) Box set com os quatro discos da banda remasterizados recebe o título da tour de mesmo nome: SHO'NUFF - The Complete Black Crowes, cada um com músicas inéditas ou versões alternativas. Como bônus um quinto CD extra gravado ao vivo durante a tour.
- By Your Side (1999) Após assinarem contrato com a Columbia Records, é lançado em 1998 o quinto álbum, By Your Side. Produzido por Kevin Shirley, um dos colaboradores do Aerosmith, o disco é uma espécie de retorno às origens. Musicalmente, os irmãos Robinson nunca estiveram tão entrosados. O rockão "Go Faster", o já sucesso "Kickin'My Heart Around" e a porrada "HorseHead" fazem deste um álbum coeso.
- Greatest Hits 1990-1999: A Tribute to a Work in Progress (2000) Coletanêa contendo 16 sucessos da banda. Cada disco tem pelo menos 2 músicas incluídas nessa coleção. Essencial para quem não conhece nada de Black Crowes.
- Live at the Greek (2000) (comJimmy Page) Em 2000 lançam o álbum Jimmy Page and the Black Crowes Live at the Greek, que consiste principalmente nos padrões Led Zeppelin de se fazer música. Versões de clássicos zeppelianos com o toque especial dos irmãos Robinson fazem deste um disco empolgante do começo ao fim, com destaque para a alucinante versão de "Ten Years Gone". Esse álbum arrepiou alguns conservadores no mundo da indústria fonográfica, por sua distribuição inicial ter sido feita online
- Lions (2001) Sexto albúm de estúdio.
- Live (2002) Disco duplo ao vivo.

Integrantes (desde 1989)

- Chris Robinson - vocals, harmonica (1989-present)
- Rich Robinson - guitar (1989-present)
- Jeff Cease - guitar (1989-1992)
- Johnny Colt - bass (1989-1999)
- Steve Gorman - drums (1989-2002; 2005-present)
- Marc Ford - guitar (1992-1999; 2005-present)
- Eddie Harsch - keyboards (1992-present)
- Audley Freed - guitar (1999-2002)
- Sven Pipien - bass (1999-2001; 2005-present)
- Greg Rzab - bass (2001-2002)
- Andy Hess - bass (2002)
- Bill Dobrow - drums (2005)

Links Externos

- [http://www.blackcrowes.net/ Black Crowes.net]
- [http://www.blackcrowes.com/ Site oficial] Black Crowes, The

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