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Stern tube


  • Seal is gripping on to the chrome liner.Chrome liner is bolted on to propeller boss(aft)
  • Fwd chrome liner is fitted on to a clamp ring . Clamp rings are of 2 halves and have holes.
  • Aft  sealing assembly consist of 2 main and 1 aux sealing rings.All sealing rings are spring loaded .Fwd sealing ring prevent oil leakage to sea .Lip seals hold oil within Stern tube and accepts small misalignment
  • Chrome liner act as rubbing surfaces for lip seals .The chrome liner at the aft end protects the steel shaft from seawater and corrosion .Grooving will not happen on the shaft because of liner, so that the chrome liner can be machined or can be shifted axially by putting spacer.If grooving occurs leak will start.
  • As per diagram the space between  #2 and #3 is connected to header tank ,#3s is the spare seal 
  • If water content found on the stern tube that means along with #1 and #2 , then #3 seal is also leaking.Then we have to put #3s seal in use.

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