Topics

1. MECH 1200 Chapter 9 Bearings Topics • Introduction to bearings • Types of bearings • Plain bearings • Antifriction bearings • Axial and Radial Loads • Questions

2. MECH 1200 Introduction Purpose of bearings: • Support loads • Reduce friction The PV factor: • PV factor refers to the Pressure and Velocity ratings of the bearing. • Pressure is the load on the bearing in pounds divided by the projected area in square inches. • Velocity is the surface velocity of the shaft.

3. MECH 1200 Some types of Bearings Plain (Journal) Bearings Antifriction (rolling) Bearings Solid Deep Groove Ball Bearing Split Angular Contact Ball Bearings Self Aligning Ball Bearing Pure Thrust Ball Bearing Cylindrical Roller Bearing Spherical Roller Bearing Tapered Roller Bearing Needle Roller Bearing

4. MECH 1200 Plain Bearings • Other names: journal, friction, or sleeve bearings • They work by sliding action in contrast to rolling action of the antifriction bearings. • Types: Solid and split types • Advantages: • Can handle high loads • Quite operation: because no rolling elements exist. • Require less space than antifriction bearings. • Low cost • Disadvantages: • Limited to low speed applications • Require precise alignment • Lubrication is essential for their performance.

5. MECH 1200 Antifriction Bearings • Parts: inner ring, outer ring, rolling element, and retainer. • They work by rolling action. • Advantages: • Higher efficiency than plain bearings • Can handle high speeds • Can tolerate misalignment better than journal bearings • Bearing Types by rolling elements: • Ball bearings • Cylindrical Roller Bearings • Taper Roller Bearings • Spherical Roller Bearings • Point contact vs line contact: Ball bearings make a point contact with the race, but cylindrical bearings make line contact, therefore ball bearings are more efficient, but cylindrical roller bearings can handle higher loads. Spherical roller Taper roller • Ball Cylindrical roller

6. MECH 1200 Axial and Radial Loads Radial Load

7. MECH 1200 Axial and Radial Loads Some bearings are designed to handle only radial loads, others are designed to handle axial loads, others are designed to handle a combination of both. Radial load Radial load Axial load Axial (thrust) load

8. MECH 1200 Light radial load Ball Bearings Moderate radial load Light axial load Light axial (thrust) load Deep groove ball bearing Self-aligning double row ball bearing Light radial load Moderate radial load Angular contact ball bearing High axial load High axial load Single acting thrust ball bearing

9. MECH 1200 Other Antifriction Bearings High radial load High radial load Low axial load Moderate axial load Cylindrical roller bearing Spherical roller bearing Tapered roller bearing High radial load High axial load Needle roller bearing

10. MECH 1200 Questions • What other names are plain bearings called? Other names are journal, friction, or sleeve bearing • Why cylindrical roller bearings can handle more radial load than ball bearings can? Because the cylindrical roller element makes a line contact with the rings, but the ball bearing makes a point contact, therefore a higher pressure is exerted on the ball element from the load. • Which of the two bearings mentioned above is more efficient? Ball bearings because of the less contact area, and less friction.

11. MECH 1200 • What type of bearing is shown in the figure below? • Journal bearing • Double row deep groove ball bearing • Spherical roller bearing • Self aligning double row ball bearing • Tapered roller bearing • The bearing is designed to carry: • High radial loads • High axial loads • Moderate radial but high axial loads • High radial and axial loads • It only can carry light loads

12. MECH 1200 • Determine if each of the following bearings is loaded correctly or not: • These bearings shown above are: • Friction bearings • Journal bearings • Plain bearings • Antifriction bearings Incorrect Incorrect correct Incorrect correct