How do you measure stern tube bearing clearance?
How to check Stern tube wear down? ( Lignum Vitae, water cooled stern tube)
- Measurement can be taken by Wedge Gauge or Feeler.
- If Wedge Gauge is used, the side of the Wedge contacting the bearing is chalked and inserted into the clearance space between top of the screw shaft and bearing.
How many end seals are required on an oil filled stern tube?
Oil lubricated sterntube requires two types of seals, one water/oil seal for the external arrangement (aft seal) and one oil seal for the inboard end (forward seal).
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.
What is the purpose of lubrication of stern tube?
A stern tube oil is necessary to provide lubrication to stern tube bearings and propeller shaft seals, deliver excellent hydrolytic stability and maintain oil integrity should water ingress occur.
What is oil clearance?
A difference between the bearing and the journal diameters allows the journal to shift from the concentric position and form a wedge. Thus the wedge parameters are determined by the difference between the diameters. This is called oil clearance (or bearing clearance).
Which is the best material for stern tube seal?
Materials such as fibrous rope, oakum, carbon and graphite based materials have been used for as long as there have been rotating shafts driving ships through the world’s oceans.
Why are seals provided in the stern tube?
Stern tube seals for inland and seagoing vessels The aft seal prevents seawater from contaminating the stern tube oil, which may possibly jeopardise the lubrication properties of the oil, leading to extensive bearing wear. The aft seal also prevents oil leaking into the marine environment.
Which of the following statements best describes an oil lubricated stern tube bearing installation?
Which of the following statements best describes an oil lubricated stern tube bearing installation? It receives its oil supply from a branch line of the main lube oil system. No shaft liner is needed in the area of the babbitted bearing surface.
Which bearing is used in stern tube?
The bearing allows the propeller shaft to rotate with as less friction as possible. Stern tube bearings are of the slide bearing type (also referred to as journal bearings or plain bearings).
How many bearings A stern tube consist of?
The amount of bearings used in a stern tube varies, but a set-up of one aft bearing and a forward bearing is a common solution. A stern tube is a precisely machined weldment consisting of several tubes, the bearings are press-fitted into the stern tube.
What is the bearing oil clearance?
The typical rule that most engine builders follow is that bearing clearance establishes the viscosity of the oil to use within a given oil temperature range. Generally, the tighter the bearing clearance, the lower the viscosity the engine can use while wider clearances require thicker oil.
How do you measure oil clearance?
With both bolts stretched, we then place the dial bore gauge to read the vertical oil clearance directly in line with the rod. It’s important to always measure oil clearance in the true vertical plane as all bearings are designed with an eccentricity to produce additional clearance at the bearing parting line.
What is lip seal in stern tube?
Lip seal is a type of sealing arrangement used on ships at the stern tube arrangement. The lip seal forms a part of stern tube bearing and sealing arrangement and is the most commonly used sealing arrangements on ships today.
What are the types of stern tube?
Different Types of Stern Tube Seals
- labyrinth Seals.
- Mechanical Face Seals.
- Packing Type.
What is poker gauge?
This poker gauge is used to measure the propeller shaft drop. Additional, make sure to turn the blade to one position refer to the marking. Normally, we take top measurement and bottom measurement. All measurements will be taken according to IACS standards.
What is the bearing clearance of a stern tube?
Figures of 3.8 mm for a shaft of 300 mm diameter to 7.4 mm for a 900mm diameter shaft have been quoted, with bearing clearances of 0.51-0.63 mm and 1.53-1.89 mm respectively. The forward part of the stern tube is fabricated and welded direct to the extension of the stern frame boss and into the aft peak bulkhead.
What is an oil-lubricated stern bearing?
Oil-lubricated stern bearings use either lip or radial face seals or a combination of the two. Lip seals are shaped rings of material with a projecting lip or edge which is held in contact with a shaft to prevent oil leakage or water entry.
What is an oil lubricated stern tube?
Oil-lubricated stern tubes Progress from sea-water to early oil-lubricated stern tubes involved an exchange of the wooden bearing in its bronze sleeve for a white metal lined cast iron (or sometimes bronze) bush. Oil retention and exclusion of sea water necessitated the fitting of an external face type seal.
What are the benefits of seawater lubricated stern tube bearings?
Thordon seawater lubricated stern tube bearings Research presented at a recent RINA (Royal Institute of Naval Architects) conference noted the benefits of seawater lubricated propeller shaft bearings: “Traditionally, the shaft line is oil lubricated, and located inside the tube case with a diameter larger than the shaft itself.