Question

Reason For Making Gear Teeth Harder
Why are gear teeth made harder? (a) To avoid wear. (b) To avoid pitting. (c) To avoid abrasion. (d) To avoid tensile strength.

Answer 1

A toothed machine part, for example, a wheel or barrel, that cross sections with another toothed part to transmit movement or to alter speed or direction.

The answer to this question is to avoid pitting because it is a surface fatigue failure of the gear tooth and the reason for this is that it is loaded repeatedly and because of this the contact stress exceeds the surface fatigue strength.

The material used in the fatigue region gets removed by doing it repeatedly and there the pit is formed instead.

Answer 2

To avoid wear, the gear teeth are made harder:
Reason:

* Since gears are used to transmit power in mechanical parts there will  be considerable amount of load on gears while in contact with each other.
* The point of contact will be at the tooth of the gears, where the load is concentrated.
* So, it is necessary that the tooth is hard enough to avoid wear and tear.

Conclusion:
so correct option is (A) --- To avoid wear