Gear Failure

Failure in gears occur due to mainly these two reasons:

1. Failure due to breakage.

2. Surface failue.

Breakage failure:

Breakage of tooth normally occurs at the root of tooth around the fillet which is under tension because this is the area which is highly stressed. Breakage may occur due to high stress or fatigue. In failure due to high stress, tooth breaks down when the loading exceeds the ultimate tensile stress of the material. This type of failure is not very common and may occur due to load reaching accidentally high value, for example , due to drive getting jammed. Breakage failure is mainly due to:

i. Incorrect assessment of load.

ii. Impact loads.

iii. Misalignment of the axes of mating gears.

iv. Errors in gear teeth.

Surface failure:

Most common observed surface failures are:

i. Failure due to pitting.

ii. Failure due to plastic flow.

iii. Failure due to scoring or scuffing.