gears are machine elements which used to transmit motion and power by the successful engagement of teeth. Two gears engaged with each other, the "gear" is having the larger number of teeth and the "pinion" is having the smaller number of teeth. It is said to be failed when any component is unable to perform one or more of its functions well before its expected service life. Bevel gears are widely used to transmit motion and power at shaft angle of 90° or else and it is widely used in gearbox. If it fails it is a major problem considering criticalness as it will fail to transmit motion and power and the whole assembly will fail to work.