High Frequency Vibration Monitoring Techniques for Gear/Bearing System Failure Detection

AGMA Technical Paper No. 109.36

Presented at the 1975 AGMA Semiannual Meeting in Montreal, Canada

Authors: Raymond J. Drago, Senior Engineer, Advanced Power Train Technology

David B. Board, Diagnostics Technology Manager, Product Assurance

Boeing Vertol Company

Philadelphia, PA

Introduction

A cooperative effort involving the Advanced Power Train Technology and the Product Assurance departments has been undertaken to investigate the feasibility of applying high frequency vibration monitoring techniques for detecting and monitoring the progression of defects in a gear/bearing system. A series of tests were conducted using gears with both implanted and developed flaws. The results of this testing indicate that the method employed may be used successfully to monitor the internal condition of gearboxes and transmissions on a periodic basis. This method has also been shown to be effective in detecting faults (e.g. cracks) which initially produce no debris. ( Methods such as spectral oil analysis, chip detectors, indicating screens, etc. depend on debris generation for their effectiveness).

The test program was conducted on the Boeing Vertol gear research test stand. The test specimens utilized were 4.55 pitch, 33/58 ratio, spur gears. Pinion speed was maintained at 2,400 rpm at torque levels ranging from 1,500 inch pounds to 35,000 inch pounds on this four-square locked in torque rig.