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

Introduction Purpose of bearings: Support loads Reduce friction MECH 1200 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.

Plain (Journal) Bearings Antifriction (rolling) Bearings 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

Plain Bearings Other names: journal, friction, or sleeve bearings MECH 1200 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.

Antifriction Bearings 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

Axial and Radial Loads Radial load Radial load Axial load MECH 1200 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

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

Other Antifriction Bearings MECH 1200 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

Questions What other names are plain bearings called? MECH 1200 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.

What type of bearing is shown in the figure below? 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

These bearings shown above are: 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 correct Incorrect Incorrect correct Incorrect

Do the student exercise on page 235 of the text. MECH 1200 Homework Do the student exercise on page 235 of the text. Answer questions 1,2,34,8,10, and 14 on page 236.