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    bearing

    Types of Bearings
    There are many types of bearings, each used for different purposes. These include ball bearings, roller bearings, ball thrust bearings, roller thrust bearings and tapered roller thrust bearings.
    Ball Bearings
    Ball bearings, as shown below, are probably the most common type of bearing. They are found in everything from inline skates to hard drives. These bearings can handle both radial and thrust loads, and are usually found in applications where the load is relatively small.


    Photo courtesy The Timken Company
    Cutaway view of a ball bearing


    In a ball bearing, the load is transmitted from the outer race to the ball, and from the ball to the inner race. Since the ball is a sphere, it only contacts the inner and outer race at a very small point, which helps it spin very smoothly. But it also means that there is not very much contact area holding that load, so if the bearing is overloaded, the balls can deform or squish, ruining the bearing.

    Roller Bearings
    Roller bearings like the one illustrated below are used in applications like conveyer belt rollers, where they must hold heavy radial loads. In these bearings, the roller is a cylinder, so the contact between the inner and outer race is not a point but a line. This spreads the load out over a larger area, allowing the bearing to handle much greater loads than a ball bearing. However, this type of bearing is not designed to handle much thrust loading.

    A variation of this type of bearing, called a needle bearing, uses cylinders with a very small diameter. This allows the bearing to fit into tight places.


    Photo courtesy The Timken Company
    Cutaway view of a roller bearing


    Ball Thrust Bearing
    Ball thrust bearings like the one shown below are mostly used for low-speed applications and cannot handle much radial load. Barstools and Lazy Susan turntables use this type of bearing.


    Photo courtesy The Timken Company
    Ball thrust bearing


    Roller Thrust Bearing
    Roller thrust bearings like the one illustrated below can support large thrust loads. They are often found in gearsets like car transmissions between gears, and between the housing and the rotating shafts. The helical gears used in most transmissions have angled teeth -- this causes a thrust load that must be supported by a bearing.


    Photo courtesy The Timken Company
    Roller thrust bearing


    Tapered Roller Bearings
    Tapered roller bearings can support large radial and large thrust loads.


    Photo courtesy The Timken Company
    Cutaway view of (left) a spherical roller thrust bearing and (right) a radial tapered roller bearing



    Tapered roller bearings are used in car hubs, where they are usually mounted in pairs facing opposite directions so that they can handle thrust in both directions.


    Some Interesting Uses
    There are several types of bearings, and each has its own interesting uses, including magnetic bearings and giant roller bearings.
    Magnetic Bearings
    Some very high-speed devices, like advanced flywheel energy storage systems, use magnet bearings. These bearings allow the flywheel to float on a magnetic field created by the bearing.

    Some of the flywheels run at speeds in excess of 50,000 revolutions per minute (rpm). Normal bearings with rollers or balls would melt down or explode at these speeds. The magnetic bearing has no moving parts, so it can handle these incredible speeds.

    Giant Roller Bearings
    Probably the first use of a bearing was back when the Egyptians were building the pyramids. They put round logs under the heavy stones so that they could roll them to the building site.

    This method is still used today when large, very heavy objects like the Cape Hatteras lighthouse need to be moved.

    Earthquake-Proof Buildings
    The new San Francisco International Airport uses many advanced building technologies to help it withstand earthquakes. One of these technologies involves giant ball bearings.



    Click on "Earthquake!"
    to see the earthquake bearing support system at work.
    The 267 columns that support the weight of the airport each ride on a 5-foot-diameter (1.5-meter) steel ball bearing. The ball rests in a concave base that is connected to the ground. In the event of an earthquake, the ground can move 20 inches (51 cm) in any direction. The columns that rest on the balls move somewhat less than this as they roll around in their bases, which helps isolate the building from the motion of the ground. When the earthquake is over, gravity pulls the columns back to the center of their bases.

    For more information on bearings and related topics, check out the links on the next page.


    http://science.howstuffworks.com/bearing5.htm

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    ابوحسن77
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    وسام الشكر

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    السلام عليكم
    جزاك الله خيرآ أخى مجدى
    وهنا بعض الكتب المفيده :
    http://www.arab-eng.org/vb/showthread.php?t=41563

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    { الَّذِينَ آتَيْنَاهُمُ الْكِتَابَ يَعْرِفُونَهُ كَمَا يَعْرِفُونَ أَبْنَاءَهُمُ }

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    ثبت في سنن الترمذي وابن ماجه أن النبي صلى الله عليه وسلم قال :

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    جاري التحميل لانملك لك ان نسال الله ان يجزيك الله خيرا على تميزك المتجدد فى كل يوم ومزيدا من التميز يا محب الله

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    و على تميزك المتجدد فى كل يوم ومزيدا من التميز يا محب الله

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  8. [8]
    wael gamil sayed
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    Bearing Data

    Bearing codes need not be a puzzle
    Here we will try & explain some of the bearing data that could help you have a better understanding of what at first might just look like a bunch of numbers,

    We will start with the most common asked questions,

    Bearing Suffixes:

    Suffixes are used to identify designs or variants which differ in some way from the original design, or which differ from the current standard design, each bearing manufacture have there own suffix & this is where it becomes a little confusing,

    The most commonly used suffixes are listed below,

    Suffix RS, LU, DU, RSR, E
    Bearing with one rubber seal
    Example 6205 LU

    Suffix 2RS, 2RSH, 2RS1, LLU, DDU, 2RSR, EE
    bearing with two rubber seals
    Example 6205 LLU

    Suffix Z, ZR
    bearing with one metal shield
    Example 6205 ZR

    Suffix 2Z, 2ZR, ZZ
    bearing with two metal shields
    Example 6205 2Z

    Suffix NR
    bearing with snap ring groove & snap ring
    Example 6205 NR

    Suffix RSNR
    bearing with one rubber seal & snap ring groove with snap ring
    Example 6205 RSNR





    Suffix 2RSNR, 2RS1NR, 2RSHNR, 2RSRNR, LLUNR, DDUNR, EENR
    bearing with two rubber seals & snap ring groove with snap ring
    Example 6205 2RS1NR

    Suffix 2ZNR, ZZNR, 2ZRNR
    bearing with two metal shields & snap ring groove with snap ring
    Example 6205 2ZNR

    Suffix ZNR
    bearing with one metal shield & snap ring groove with snap ring
    Example 6205 ZNR

    Suffix M, MA, MB, ML, MP, BR
    bearing with brass cage
    Example 6318 MA

    Suffix ETN9, TNH, TN, ETVP2, TN9, ETVP, TVP, ECP, E.G15, ET, ETN, ET2X
    bearing with polymide plastic cage
    Example N205 ETN9

    Suffix C2, F3
    bearing with internal clearance smaller than normal
    Example 6205 C2

    Suffix C3, J30, F4
    bearing with internal clearance greater than normal
    Example 6205 C3

    Suffix C4
    bearing with internal clearance greater than C3
    Example 6205 C4

    Suffix C5
    bearing with internal clearance greater than C4
    Example 6205 C5

    Suffix GJN
    bearing with high temp grease -30 to +150 ºC
    Example 6205 GJN

    Suffix HT
    bearing with high temp grease -40 to +150 ºC
    Example 6205 HT



    Suffix WT
    bearing with high temp grease -40 to +160 ºC
    Example 6205 WT

    Suffix VL0241
    bearing with aluminium oxide coated outside surface of the outer ring for electrical resistance up to 1000 V DC
    Example 6317 MC3VL0241

    Suffix VL2071
    bearing with aluminium oxide coated outside surface of the inner ring for electrical resistance up to 1000 V DC
    Example 6324 C3VL2071

    http://www.bearing-king.co.uk/bearing-data.php

    http://www.myzips.com/result.phtml?keyword=bearing

    http://www.skf.com/portal/skf/home/p...&newlink=1_1_0

    http://www.bearing-king.co.uk/how-to...-a-bearing.php

    http://en.wikipedia.org/wiki/Bearing_(mechanical)

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