GENERAL INFORMATION OF BEARINGS
Hundred of years ago, when man lacked strength and endurance to carry loads, such heavy loads to be transported were put on simple skids and dragged to the place of destination. The dragging heavy load on dry ground requires considerable force. These forces can be reduced by using lubricants between the sledge runners and the ground. This lubricant-probably water – was poured to reduce the friction and thereby reducing the volume of force. As the time passed on, these forces were further reduced when man learnt to insert wooden rollers between the ground and the object. THUS SLIDING MOTION WAS CONVERTED INTO ROLLING MOTION, which is the basic principle of bearing. However, things were not much changed for years, till the concept of BALL was conceived, as the application of rollers was not practical everywhere.
In 17th century, stone balls were produced and were in use for variety of applications to minimize the friction. Since the stone balls were not suitable for many applications, cast iron balls were also produced, but that was also not suitable. In 19th century, the concept of steel balls was conceived and steel balls were produced. During this era, on lathe machines, balls of remarkable accuracy were cut off from a steel rod and the ends were machined to form a sphere. At the end of 19th century, balls manufactured by this method in England were within the tolerance of 0.025 to 0.050 mm. In the year 1883, Friedric Fischer, instrument maker in Scheweinfurt – W. Germany, after numerous experiments, developed a method of grinding wheel balls, turned between the centers on the centre less principle. For this purpose, he designed ball grinding machine called “BALL MILL”. In 1898 taper roller bearing unit developed in USA by H. Timken. During 1913-1914 Roller bearings were put on use.
The choice of a bearing depends on many factors that need to be examined in order to obtain the most successful results at the lowest cost. In most cases the selection should be made when the overall design of the machine has been decided. Dimensional limits are then known, as well as the speeds and loads. At this stage the choice can be made from the many types of bearings offered from the Galaxy Bearing Ltd. standard ranges and the notes given in this section will generally permit selection of the most suitable bearing for each application. When calculating the cost of the assembly, not only should the price of the bearing be considered, but also cost for heat treatment, machining and handling and fitting of ancillary items (snap rings, locking devices, tools etc.) and the eventual quantities required. Large economies can be made on these items if the correct bearings are selected. Something it is more advantageous to choose a bearing of slightly higher cost, which will however, when all criteria are taken into consideration, provide the most economic solution. The result obtained from bearings depends to a large extent on the design and method of assembly, loading, and alignment between inner and outer rings. The introduction of 'Anti-friction' or 'Rolling Contact Bearing' proved far superior to plain Bearings because of their classic advantages, Such as
- Low friction - particularly low starting friction.
- Their ability to support both radial and thrust load and speed.
- Accurate performance under changing load and speed.
- High load carrying capacity.
- Operating ability under extreme conditions of speed and temperature.
These bearings vary in size, from 'tiny pin-head' to 'giant sized' Bearings for Cement/Rolling Mills/Radars etc.
Bearings are so widely used that today, we find their application in objects like the charkha, chairs, doors, filling-cabinets, children's toys, as well as in the most sensitive instruments like computers, data processing machines, rockets and aerospace instruments.
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