CBSE Class 12 Engineering Bearings. Students can download the specific chapters from the CBSE and NCERT text books from studiestoday.com. Please refer to the attached file to access the chapters. The books and specific chapters have been collected by the tutors on studiestoday for the benefit of CBSE students. They can access these chapters anywhere and use them for their studies.
All of you have seen a bicycle and most of you may know how to ride it. With the help of paddles you may have driven it. It needs very little effort to run a bicycle. Do you know why a bicycle runs so smoothly and easily? The reason is that friction is greatly reduced by using bearings in the moving parts and you must have oiled/ greased these bearings from time to time.
In the industry also the bearings are used to help in smooth running of the shafts. As we all know that the friction is a necessary evil. The friction generates heat and opposes the free movement of the moving parts. We can not eliminate the friction together but we can reduce it to a large extent by using some suitable lubricant.
The meaning of bearing as given in the Dictionary is a part of a machine which support another part that turns round a wheel' or it can be defined as the support and guide for a rotating ,oscillating or sliding shaft, pivot or wheel' .
Bearings are used as a mechanical component to a certain part and this is done by utilizing the small frictional force of the bearings, which makes them rotate easily, all the while with the force and load acting against them.
There are two types of bearings according to the type of motion:
1. Plain bearings and
2. Anti-Friction bearings or Rolling Bearings
We will learn that plain bearings are such that they primarily support sliding, radial and thrust loads and linear motions also.
1. Plain Journal Bearings: These support radial loads at right angles to the shaft axis.
2. Spherical Bearings: These are used where the loads are not aligned and are radial.
3. Thrust Bearings: These bearings support axial and radial loads.
4. Linear Bearings: These bearings only help in linear motion.
5. Pivot Bearings or Foot Step Bearings: These bearings are used where the thrust is only axial.
CLASSIFICATION OF BEARINGS
Plain bearings may further be classified as:
ANTI-FRICTION OR ROLLER BEARINGS
These bearings can be:
1. Needle Bearings.
2. Ball Bearings and
3. Roller Bearings.
The bearings mentioned above can be rearranged according to the loading conditions as:
1. Journal Bearings: In this bearing the bearing pressure is perpendicular to the axis of the shaft.
2. Thrust Bearing or Collar Bearing: In this bearing the pressure is parallel to the axis of the shaft.
3. Pivot Bearing: In this bearing the bearing pressure is parallel to the axis of the shaft and the end of the shaft, rests on the bearing surface.
4. Linear Bearings
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