Oil lubricated sterntube bearing, sterntube seals & shafting arrangement. It consists of a cast-iron or casted steel cylinder fitted with bearing surface within which the propeller shaft, enclosed in a sleeve, rotates. The sterntube is installed from aft and bolted to the stern frame boss.
How does the stern tube bearing being lubricated?
Sterntube Bearing They are lubricated by the bath of lubricant that they are submerged in and operate hydrodynamically when the shaft is rotating. Two main types of Sterntube bearings exist, which are: Oil lubricated white metal bearings – fitted to most ships and filled with oil to provide lubrication and cooling.
How frequently is stern tube oil send for analysis?
The IACS (International Asssociation of Classification Societies) in UR Z21 states that Stern Tube lubricating oil analysis is to be carried out at regular intervals not exceeding six (6) months, taking into account IACS Rec.
What is the stern tube arrangement?
The stern tube is a hollow tube passing at the lower stern part of the ship carrying tail shaft and connecting it to the propeller out at sea, bearing for the tail shaft, lubrication arrangement and most importantly the sealing arrangements.
What is stern tube seals?
A housing with series of seal rings clamped into position on the bush. Sterntube seals have to perform two separate functions, one is to ensure that water does not enter the engine room, the second one to allow the propeller shaft to rotate as smoothly and freely as possible.
How many bearings A stern tube consist of?
Oil-lubricated white metal bearing usually consists of two bushes pressed into a stern-tube. Water lubricated bearings use only seawater for lubrication, thereby they eliminate any risk of oil pollution from the sterntube.
What is crackle test?
The crackle test is a standard laboratory test to detect the presence of water in lubricating oil. A drop of oil is placed on a hotplate that has been heated to approximately 400° F. The sample then bubbles, spits, crackles or pops when moisture is present.
How many bearings does a stern tube have?
Why lip seal is used in stern tube?
The first two lip seals form a barrier against water ingress and the third one prevents oil leakage from the stern tube into the surrounding water.
What is stern tube?
The stern tube is a hollow tube which accommodates the bearings, the seal boxes and the propeller shaft. The stern tube is filled with oil, grease or water and forms a barrier between the water outside and the engine room inside the vessel.
How do you check stern tube bearing clearance?
Stern Bearing Wear-down Measurement:
- Use Poker Gauge or Wear down Gauge or Vernier Caliper.
- Remove Rope Guard.
- Take out Check Plug and Drain Plug.
- Turn Tailshaft until ‘0’ marks on periphery of aft chrome steel liner flange and mating marks on Simplex seal and Sterntube are in line.
