INTERSHAFT BEARING RECONDITION AND LOAD TEST

1. Problem Description

      In June 2025, MTB Engineering Service Co., Ltd was called upon to address a critical failure of an intershaft bearing on a commercial vessel. The issue had resulted in abnormal vibrations, elevated bearing temperatures… within the main engine shaft system.

      Upon preliminary inspection by MTB technicians, a slight misalignment between the inner and outer shafts was confirmed. The journal surfaces displayed signs of scoring and heat damage, indicating prolonged friction and thermal stress. Additionally, the bearing material showed severe wear and partial delamination, suggesting compromised structural integrity. The lubricating oil was found to be degraded, likely due to overheating and the accumulation of impurities, further contributing to the bearing's poor performance.

      2. Repair Process

     After dismantling the intershaft bearing unit, MTB carried out essential reconditioning steps, including journal polishing, dimensional checks, re-metalizing at shore workshop, and precise reassembly with alignment verification. The unit was reinstalled with new seals and fresh lubricating oil, following OEM and class requirements

      3. Outcome

      Post-repair testing yielded excellent results:

• No more vibration or overheating at the intershaft bearing
• Temperature readings returned to normal operating range
• No abnormal noise during sea trial or load tests
• Shaft alignment was within acceptable tolerances
• Lubricating oil condition remained stable and clean after operation

     4. Customer Feedback

      The client expressed satisfaction with the professional and timely service provided by MTB. After returning the vessel to full operation, no recurring issues were reported related to the intershaft bearing area.