Gears are defined as toothed wheels or multi-lobed cams, which transmit power and motion from one shaft to another by means of successive engagement of teeth. Gear drives offer the following advantages compared with chain or belt drives:

  1. It is a positive drive and the velocity ratio remains constant.
  2. The centre distance between the shafts is relatively small, which results in compact construction.
  3. It can transmit very large power, which is beyond the range of belt or chain drives.
  4. It can transmit motion at very low velocity, which is not possible with the belt drives.
  5. The efficiency of gear drives is very high, even up to 99 per cent in case of spur gears.
  6. A provision can be made in the gearbox for gear shifting, thus changing the velocity ratio over a wide range.

Gear drives are, however, costly and their maintenance cost is also higher. The manufacturing processes for gears are complicated and highly specialised. Gear drives require careful attention for lubrication and cleanliness. They also require precise alignment of the shafts.

How to generate the involute of base circle

An Example of a Geartrain 


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