AGMA 912-A04 pdf free download.Mechanisms of Gear Tooth Failures.
3.3 How to analyze gear failures
3.3.1 Failure conditions
When gears fail, there may be Incentive to quickly repair or replace failed components and return the gear system to service. However, because gear failures provide valuable data that may help prevent future failures, a systematic inspection procedure should be followed before repair or replacement begsL
The failure investigation should be carefuly planned to preserve evidence. The specific approach can vary depending on when and where the inspection is made, the nature of the failure, and tiie constraWts.
3.3.1.1 When and where
ldeaIlç the site visit and failed components should be inspected as soon after failure as possible. If an early rnspection is not poss1e, someone at the site must preserve the evidence based on specific rnstniction
3.3.1.2 Nature of failure
The failure conditions can determine when and how toconductananalysis. ltisbesttoshutdown alailing gear unit as soon as possible to lnet damage. To preserve evidence, carefully plan the failure Inves tigatlon including shutdown, in-situ inspections, gear unit removal, transport, storage, and disassembly. However, If the gears are damaged but still functional, the company may decide to continue operation and monitor damage progression. In this case, the gear system should be monitored under experienced supervision. For critical applications, examine the gears with magnetic particle or dye penetrant inspection to ensure there are no cracks before operation is continued. In all applications, check for damage by visual inspection and by meas&aing temperature, sound, and vibration. Collect samples of lubricant for analysis, drain and flush the reservoir, and replace the lubricant Examine the oil filter for wear debris and contaminants, and Inspect magnetic plugs for wear debris.
3.3.1.3 Time constraints
In some situations, the high cost of shutdown limits time avaable for inspection. Such cases cal for careful planning. For example, dividing tasks between two or more analysts reduces time required.
3.3.2 Prepare for Inspection
Before visiting the failure site, interview on-site personnel and explain what is needed to mspect the gear unit including personnel, equipment, and working conditions.
Request a skilled technician to disassemble the equipment However, make si.we that no work Is done on the gear unit until It can be observed. This means no disassembly, cleaning, or draining of the oIL Otherwise, a well-meaning technician could inadvertently destroy evidence. Emphasize that failure Investigation is cfltterent from a gear unit rebuild, and the disassembly must be carefuly controlled.
Verify that gear unit drawings, disassembly tools, and adequate facilities are available. Inform the site supervisor that privacy is requied to conduct the investigation and access Is needed to al available information.
Obtain as much background information as possible, including manufacturers specifications, service history, load data, and lubricantanalyses Send a questionnaire to the site personnel to help expedite information gathering.AGMA 912 pdf download.