Niigata Z-Peller 41 and Z-Peller 41-CP

LR-Lloyd's-RegisterLR has issued machinery alert to inform about the modification of the lower vertical Niigata Z-Peller 41 and Z-Peller 41-CP propulsion systems.

Niigata Power Systems Company Limited recently issued Service News regarding Z-Peller 41 and Z-Peller 41-CP propulsion systems in which some wearing down of the collar was found after several years. This might affect the axial clearance of the lower vertical shaft.

To prevent this phenomenon, we recommend the periodical checking of the axial clearance and the modification of the vertical shaft assembly. We have modified some of the spare parts, the additional spacer, the harder spacer and tightening length of the bearing nut to achieve stronger structure.

Please check and modify the lower vertical shaft at next dry-docking overhaul.

  1. Seperate lower gear case from the middle unit after taking out propeller.
  2. Take out the front cover of the lower gear case.
  3. Take out propeller shaft with bearing housing after checking the axial clearance of it.
  4. Take out the strut from lower gear case by using jacking bolts and hydraulic jack.
  5. Take out vertical shaft assembly and replace the bearing housing, collar and spacer.
  6. Adjust the axial clearance of the vertical shaft and propeller shaft.
  7. Adjust backlash and contact pattern of bevel gear.
  8. Put back the strut.

Please note that the periodical checking of the driving shaft axial clearance is recommended at every five(5) years or every 15,000 hours.

Further details and relevant graphs may be found here.

Source: LR