Machinery Lubrication

Machinery Lubrication May-June 2021

Machinery Lubrication magazine published by Noria Corporation

Issue link: https://www.e-digitaleditions.com/i/1378657

Contents of this Issue

Navigation

Page 50 of 56

48 | May - June 2021 | www . machinerylubrication.com WEAR DEBRIS damaged bearing due to a small clearance between the races. No other damage was evident, and planet bearing damage was a known failure mode for this type of gearbox. Initially, this failure mode was thought to fall in the "run to failure" mode. To mitigate risks while a gearbox replacement plan was being formulated, a Poseidon wear debris sensor was sourced to monitor the debris generation within the gearbox. Low levels of debris generation were immediately evident. Debris generation was proportional to higher wind events and remained quite low during the summer seasons. Given the ability to continuously monitor the gearbox and the high-quality data recorded from the wear debris monitor, it was decided to continue to run the defect to capture the failure "signa- ture." is could then be used to gauge the degree of damage progression in other gear- boxes with the same failure mode. During the monitoring of this gearbox, another gearbox was diagnosed in the extreme early stages of the same failure with a few particles on the oil filter. The Cost-Saving Solution A repair on the early-stage gearbox in which the planet bearings were successfully exchanged while the gearbox remained in the tower was made. A much smaller crane was used, and the repair cost was 25% of the cost of complete gearbox replacement. is cheaper repair made early detection of the failure mode a critical component of proper maintenance. is method was even more economical when the work could be grouped to utilize the same crane and traveling crew on several repairs in succession. e wear debris monitors allow operators to scan for a rapid increase in debris generation, signaling a significant change in machine condition has occurred. is continuous window into the machine condition reassures the operator that continued safe operation of the machine is possible until a step change in debris generation is observed. Even when a step change in particle generation is noticed, the blade pitch schedules can be altered on the turbine to effectively lower the stresses on the gearbox, reducing particle liber- ation. Particle generation feedback was used to find the optimum pitch schedule to maximize production while minimizing bearing damage. Once particle generation becomes severe, the unit can be secured to prevent the gearbox from seizing. Measurable Results e "run to failure" unit, as shown in the graph below, was run for 2.5 years before particle generation reached extreme levels. e wear debris monitor showed increasing levels of wear debris generation each year before exhibiting a step change, presumably when the bearing race experienced a through crack. Although the unit was slated to receive a complete gearbox exchange, the planet bearings were exchanged using the "uptower" method at a significant savings. Once disassembly was complete, it could be seen that 2 of the 6 planet bearing races exhibited massive spalling and through cracks. Since bearing replacement, this unit has run an additional 3.5 years on the replacement bearings. e Poseidon units have helped manage 9 additional bearing replace- ments and become a valuable tool in mitigation of this failure mode. ML

Articles in this issue

Links on this page

Archives of this issue

view archives of Machinery Lubrication - Machinery Lubrication May-June 2021