1. TOPIC: BEARINGS OBJECTIVE: TO TALK ABOUT THE IMPORTANCE OF BEARINGS WHILE DESCRIBING THE DIFFERENT TYPES OF BEARINGS AND THEIR USES Presenter: SHER AFZAL PARACHA

2. Introduction A bearing is a component used to reduce friction in a machine. Bearings may be classified broadly according to the motions they allow and according to their principle of operation. The concept behind a bearing is very simple: Things roll better than they slide. Bearings reduce friction by providing smooth metal balls or rollers, and a smooth inner and outer metal surface for the balls to roll against. These balls or rollers "bear" the load, allowing the device to spin smoothly. Common motions include linear and rotary. A linear bearing allows motion along a straight line, for example a drawer being pulled out and pushed in. A rotary bearing allows motion about a center, such as a wheel on a shaft or a shaft through a housing. Common kinds of rotary motion include both one-direction rotation and oscillation where the motion only goes through part of a revolution.linearrotary

3. Main Types of Bearings Ball Bearing, which is the most common of all the types. A sphere is used in between two races which results in a very less contact area making it move very smoothly. Used in applications where there is a relatively small radial or thrust load. Roller Bearings, in which cylinders are used instead of spheres, increasing the contact area so that it holds a greater radial load. Ball Thrust Bearings are used for low speed applications and cannot handle much radial load. Roller Thrust Bearings, which can support large thrust loads. Tapered Roller Bearings can support large radial and thrust loads.

4. Ball bearing Cutaway view of a ball bearing

5. Roller Bearing Cutaway view of a Roller Bearing

6. Ball Thrust Bearings

7. Roller Thrust Bearings

8. Tapered Roller Bearings Cutaway view of (left) a spherical roller thrust bearing and (right) a radial tapered roller bearing

9. Some Uses Ball bearings are found in everything from inline skates to hard drives. Roller Bearings are used in applications like Conveyer Belt Rollers. Bars Tools and Lazy Susan Turntables use ball thrust bearings. Roller Thrust Bearings are used to support thrust loads in car transmission between gears, in between housing and the rotating shafts, etc. 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.

10. Conclusion Therefore bearings are used in a lot of different mechanical devices and are very important to make different applications durable, noiseless and efficient. References:  http://science.howstuffworks.com/bearing3.htm http://science.howstuffworks.com/bearing3.htm  en.wikipedia.org/wiki/Bearings en.wikipedia.org/wiki/Bearings