Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1356397
14 | March - April 2021 | www . machinerylubrication.com 14 | March - April 2021 | www . machinerylubrication.com ered surface deterioration on two of the four gears on the compound gear train. Damage included pitted surfaces, inden- tions, feathered edges, and uneven surfaces. Additionally, all the deterioration was on one side of the gears, indicating that the damage was occurring when the winch was pulling. is type of damage typically indicates either a lack of lubrication, high pressure gear loading or an issue with the gear material used. We were confident that the lubricant and loading were within specifications, so we focused on the gear material and decided to have them tested. We purchased a rebound hardness tester and conducted three readings on every tooth. All the gears were supposed to have a hardness above 35 Rockwell C, however two of the four gears came back below this limit. It was no surprise to us that these were the same gears that were damaged. We found the root cause. EARLY ALERT SAVED THE DAY By now, many more of the CMP's were showing signs of wear debris. Knowing this as well as the fact that many of the winch gears were not to specification, we decided to have all suspicious gears in all the twenty-two winches replaced. e cost of having just one winch fail in the middle of the job was too great. e gears had to be manufactured and there were no spares that could be pulled off a shelf. At minimum, it would have taken at least four weeks to fabricate, harden, air freight from Europe, move through customs and install. e winches were a vital part of the operation. If one of the winches failed, the rock mound operation would have stopped, and this would have delayed the building of the caisson wall, which would have ultimately slowed construction of the whole project. If the project was delayed by just one week, let alone four, because of unexpected failure of the rock mound winches, the cost to the overall project would have been unimaginable. Fortunately, the CMP alerted us to the problem well ahead of machine failure, giving us enough time to contact the supplier and have new gears manufactured and shipped. ere was also time to make the gear exchange during previously planned maintenance. Had it not been for our condition monitoring procedures, we would never have discovered the high metal content. And had it not been for the Condition Monitoring Pod, we would not have realized the extent of the problem in time to identify the root cause and prevent a very costly failure. Offshore construction projects are all about specialized equipment, and during the building of the world's largest container terminal, a specialized Pod kept our specialized vessel running so it could do a very special job. In the end, condition monitoring saved the day, and we finished constructing all of the rock mounds without any machine failures or delays. In fact, the project was so successful that we finished ahead of schedule. ML Figure 3 – After only 58 hours, large amount of ferrous wear debris can be seen on the CMP's visible magnet. Notice that the steel corrosion indi- cator has also become magnetized and has also collected debris. Figure 4 – Visible damage on two of the four gears in the winch's compound gear train. Damage included: 1) Feathered edges, 2) Uneven surface finishes, 3) Indentions, and 4) Pitting "HAD IT NOT BEEN FOR THE CMP'S WE WOULD NOT HAVE REALIZED THE EXTENT OF THE PROBLEM." COVER STORY