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Rolling Element Bearings Tapered Roller Bearings prepared by Wayne Book

Rolling Element Bearings Outline. Bearing types and nomenclatureLoads, life and failure modesBall bearing selection criteriaTapered bearingsInduced thrust loadSelectionApplication and maintenance. Roller Bearing Nomenclature (from Shigley). . . Induced thrust. Applied radial force. . Induced thrust is also transmitted to cone and hence to shaft.

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Rolling Element Bearings Tapered Roller Bearings prepared by Wayne Book

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    1. Rolling Element Bearings Tapered Roller Bearings prepared by Wayne Book ME3180 Based on Shigley and Mischke Design of Mechanical Elements

    3. Roller Bearing Nomenclature (from Shigley)

    4. Calculating Tapered Bearing Loads

    5. Effective Radial Loads For sizing bearing the effective radial load will be used. If the effective radial load is less than the actual radial load, use the actual load Bearing A induces thrust on B and vice versa

    6. Example Table for Bearing Selection

    7. Steps in Tapered Roller Bearing Selection Given required bearing life L10 and load arrangment Determine applied radial Fex and thrust Tex loads Distribute radial loads to bearings: FrA and FrB using estimated a value to locate load center Estimate Bearing K factors for induced thrust Calculate equivalent radial loads FeA and FeB using estimated K factor Calculate rated load using actual load and desired life Select bearing from those available (in table) Check bearing loads using actual K factor and a values

    8. Example Selection Problem Gear transmission as shown with small gear being helical which generates thrust of 0.3 x tangential force Obtain radial loads assuming static equilibrium Use estimates of a=0 and K=1.5 to begin problem Seek life of 50,000 hours at 1000 rpm Nominal shaft diameter = 1 in. Force angles on gear at 25 degrees Use identical tapered roller bearings

    9. Example Solution

    10. Common mounting alternatives

    11. Mounting Bearings with Thrust Loading Ideally the constraints are not redundant Consider the case where thrust can reverse Arrows show load transfer for either direction Thrust in either direction carried by left bearing

    12. Alternative Mounting with Thrust Thrust load carried by one or the other bearing Dimensional inaccuracies or temperature variations causes unplanned preload

    13. Preload Arranged at One End of Shaft Controlled amounts of preload is useful to eliminate clearance if improved accuracy is needed.

    14. Misalignment Can Be Devastating Roller bearings limited to 0.001 rad Deep-groove ball bearings < 0.0047 rad Other spherical ball bearings < 0.0087 rad Estimates of life reduction in Fig. 11-18 for roller bearings (line contact bearings).

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