At MIT, we understand the unique challenges faced by the commercial fishing industry and are dedicated to providing reliable and efficient drivetrain solutions to keep fishing vessels operational and productive. This case study showcases our expertise in servicing and maintaining marine gears, ensuring our clients in the Irish, Scottish and English fishing industry experience minimal downtime.
Project Overview
A MGX5136A marine gear was received at our Queenborough site for a comprehensive strip, survey, and report. The unit required several replacements and repairs to restore its functionality. This case study details the inspection, findings, and repairs carried out by our skilled engineers.
Initial Inspection and Findings
Upon initial inspection, it was discovered that the input and output shafts turned together, indicating a drag in the clutches. The residual oil drained from the gearbox was relatively clean but had a burnt smell. The oil strainer and spacer were full of metal filings and debris, and the oil pump appeared to have been split previously.
Dismantling and Detailed Inspection
During the dismantling process, the filters on the proportional valves were cleaned, and oil was present in the PTO Adapter. The output coupling was easily lifted off by hand, and the splines were checked with no defects found. However, the output carrier ‘O’ Ring was found to be brittle. Further inspection revealed scoring in the bushing for the primary and secondary shafts, indicating that the shafts had been running off-centre. Once the housing was split, it was observed that the secondary clutch drum was sitting slightly higher than the primary clutch drum. Additionally, the secondary shaft pinion gears showed signs of hardening coming away, with chips present on the pinion gear teeth, and the clutch group had swelled. The output gears also exhibited wear.
Primary Shaft Inspection
The primary shaft inspection revealed an uneven workload on the top bearing, indicated by uneven discolouration and wear of the bearing. The clutch piston travel exceeded its tolerance, indicating wear on the clutch plates. Dismantling the shaft clutch pack revealed stepping in 6 of the 9 steel plates. The middle ‘O’ ring of the clutch piston was found to be brittle.
Secondary Shaft Inspection
The secondary shaft inspection found the top thrust washer to be broken. The clutch pack had swelled significantly, requiring pressing down to remove the retaining ring. The pinion gear hard facing had started to peel, and the bottom of the pinion gear had been running on top of the clutch piston. The clutch plates were domed, and the clutch piston was seized in the open position. Removal of the clutch piston required drilling and tapping. The piston ring was stuck, with wear present on the side of the piston. The middle seal was brittle, and the inner seal had heat damage but remained flexible.
Repairs and Replacements
To restore the MGX5136A Marine Gear to optimal condition, the following repairs and replacements were carried out:
- The cooler was returned, and the input coupling, R&D coupling, and drainpipe were swapped with new components.
- The output coupling was reinstalled after checking the splines.
- The brittle ‘O’ rings were replaced.
- The scored bushings were addressed to ensure proper alignment of the shafts.
- The damaged pinion gears and clutch group were replaced.
- The worn bearings and clutch plates were replaced.
- The broken thrust washer on the secondary shaft was replaced.
- The seized clutch piston was repaired, and the damaged seals were replaced.
Debris in strainer
Brittle ‘O’ ring
Uneven wear on bearing
Wear on pinion gear
MIT Ltd’s expertise in marine gear maintenance and repair ensures that the Irish fishing industry can rely on us for their drivetrain needs. Our thorough inspection and meticulous repair process guarantee that fishing vessels remain operational, reducing downtime and enhancing productivity. By providing high-quality service and support, we help our clients navigate the challenges of the fishing industry with confidence.
