Early Detection of Failure of Spiral Bevel Gears Used in Differential Gearbox

Abstract

Spiral bevel gears are critical machine components used in almost all automotive differential gear boxes and main rotor drive systems for rotorcrafts. In this paper, noise and vibration approach is described for condition monitoring of spiral bevel gears. A fatigue test rig is developed to test the differential gearbox of an automobile using NVH approach. Experimental tests are conducted on test spiral bevel crown wheel and pinion used in differential gear box to study the noise and vibration characteristics of the gears during operation and also to determine the fatigue life of given spiral bevel gears pair. The test gears are loaded with rated torque with a factor of safety of two, until the pinion fails. Correspondingly the data are logged to record the noise and vibration of the gear pair. The vibration and noise signals are acquired experimentally on time response, and then, these are plotted on frequency response for three different cases viz new gear pair, used gear pair and gear pair after breaking of one tooth of the crown pinion. By studying the characteristics of noise and vibration spectrum condition monitoring and fault diagnosis of the given differential gearbox is possible. By onboard measurement of noise and vibration, early detection of failure of spiral bevel gears pair during operation is accomplished.