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Bearings

Bearings. Types of bearings: Rolling contact or anti-friction bearing Journal or sleeve bearings(sliding contact bearing). Bearings are used for carrying loads while allowing relative motion(rotation) with minimum friction. Bearings.

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Bearings

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  1. Bearings • Types of bearings: • Rolling contact or anti-friction bearing • Journal or sleeve bearings(sliding contact bearing) Bearings are used for carrying loads while allowing relative motion(rotation) with minimum friction Mechanical Engineering Dept.

  2. Bearings Rolling Contact Bearings– load is transferred through rolling elements such as balls, straight and tapered cylinders and spherical rollers. Mechanical Engineering Dept.

  3. Journal (sleeve) Bearings– load is transferred through a thin film of lubricant (oil). Mechanical Engineering Dept.

  4. Bearings Journal (Sleeve) Bearings Load is transferred through a lubricant in sliding contact Mechanical Engineering Dept.

  5. Bearing load – radial, thrust (axial) or both Thrust load Radial load Radial load Design Considerations Bearings are selected from catalogs, before referring to catalogs you should know the followings: • Bearing life and reliability • Bearing speed (rpm) • Space limitation • Accuracy Mechanical Engineering Dept.

  6. Roller bearings • Cylindrical bearings(straight roller bearing) • Needle bearings • Tapered bearings • Spherical bearings Rolling Contact Bearings • Ball bearings • Deep groove ball bearing • Angular contact bearings (AC) • Self alignment ball bearing In general, ball bearings are capable of higher speeds and roller bearings can carry greater loads • Thrust bearings Mechanical Engineering Dept.

  7. Comparison of rolling contact and journal bearings • Rolling contact bearings have low starting friction and are used for applications with high starting loads(coefficient of friction between 0.001 and 0.002) • Journal bearings with hydrodynamic lubrication are suited for high rotating speeds with impact loads(the higher the rotating speed, the more effective the hydrodynamic pumping action • Rolling contact bearings take up more radial space around the shaft, but journal bearings usually require greater axial space • Rolling contact bearings produce more noise • Journal bearings are less expensive than ball or roller bearing for simple applications Mechanical Engineering Dept.

  8. Types of Ball bearings Mechanical Engineering Dept.

  9. Ball Bearings Deep groove (Conrad) bearing • Load capacity is limited by the number of balls • Primarily designed to support radial loads, the thrust capacity is about 70% of radial load capacity Mechanical Engineering Dept.

  10. Ball Bearings Angular contact bearings (AC) The centerline of contact between the balls and the raceway is at an angle to the plane perpendicular to the axis of rotation. Extra support in the back Direction of thrust • Used for high radial and thrust load applications Mechanical Engineering Dept.

  11. Self alignment bearing Mechanical Engineering Dept.

  12. Roller Bearings Roller bearings have higher load capacity than ball bearings, load is transmitted through line contact instead of point contact. Mechanical Engineering Dept.

  13. Cylindrical bearing Mechanical Engineering Dept.

  14. Needle bearing Mechanical Engineering Dept.

  15. Roller Bearings Tapered bearings Designed to withstand high radial loads, high thrust loads, and combined loads at moderate to high speeds. They can also withstand repeated shock loads. Mechanical Engineering Dept.

  16. Car wheel bearings Mechanical Engineering Dept.

  17. aa = effective bearing spread Measure of the rigidity of the bearing mounting Tapered Bearings Indirect and Direct mounting Indirect mounting provides greater rigidity when pair of bearings is closely spaced: front wheel of a car, drums, sheaves,.. Indirect mounting Direct mounting provides greater rigidity when pair of bearings is not closely spaced: transmission, speed reducers, rollers,.. Direct mounting Mechanical Engineering Dept.

  18. Roller Bearings Bearing design uses barrel shaped rollers. Spherical roller bearings combine very high radial load capacity with modest thrust load capacity and excellent tolerance to misalignment. Mechanical Engineering Dept.

  19. Tapered Thrust Bearings Roller Thrust Bearings Spherical Thrust Bearings Cylindrical Thrust Bearings Mechanical Engineering Dept.

  20. Ball thrust bearing Mechanical Engineering Dept.

  21. Flange Alternative method, inner ring is press fitted onto the shaft. Common mounting, inner ring held in position by nuts threaded onto the shaft. Two-bearing mounting Mounting Bearings Pillow Block Mechanical Engineering Dept.

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