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Feb
Water lubrication was first challenged by oil systems in 1886 and by the 1940s oil lubrication became the standard. There are three types of stern tube bearing arrangements that are used to accomplish these goals.
The small differential pressure ensures that water is excluded.
Types of stern tube lubrication system. Figure 815 Oil lubricated stern tube Simplex type The static lubrication system for vessels with moderate changes in draught have header tanks placed 23 m above the maximum load waterline. The small differential pressure ensures that water is excluded. The cooling of simple stern tubes necessitates keeping the aft peak water level at least 1 rrt above the stern tube.
Lubricant manufacturers produce a variety of different lubricants for stern tube bearings. Until Vickers produced the first bio-degradable oil in 2002 all of the lubricants for metal bearings were mineral oil-based as are most available today. The most commonly used oils are of the SAE 30 or SAE 40 types.
Seawater is the oldest lubrication for propeller shaft stern tube systems and has been a core part of the marine industry for over a hundred years. Water lubrication was first challenged by oil systems in 1886 and by the 1940s oil lubrication became the standard. The stern tube bearing consists of sealing arrangement to prevent ingress of water and to avoid the lubricating oil to escape into the sea.
Sealing arrangement The lubrication system for ships with variable draught due to loading and unloading of cargo consists of header tanks located at around 2 to 3 meters above the water line so that the differential pressure ensures no water ingress. Sterntube lubricating oil systems. In principle the sterntube aft seals can function without a lubrication system.
However the aft sealing functions better and has a longer life if it is fitted like the forward sealing with a lubrication system. Although dated permanent oil. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy Safety How YouTube works Test new features Press Copyright Contact us Creators.
Water lubricated stern tube The traditional stern bearing is water-lubricated and consists of a number of lignum vitae staves held by bronze retaining strips in a gunmetal bush. Lignum vitae is a hardwood with good wear characteristics and is. Typical Vessel Stern Tube Arrangement.
There are a few types of major stern tube seals on the market today all with one job to keep the ship moving through the water and the water out of the ship. There are three types of stern tube bearing arrangements that are used to accomplish these goals. Stuffing boxes which uses packing material to seal the area 2.
Conventional Stern Gear. These consist of a Stuffing box central tube also called the centre bearing are used around the propeller shaft at the point where the boats hull is underwater. Rings of soft packing material are placed in the stuffing box around the shaft.
Oil-lubricated stern tube systems are the most common and occasionally ship owners require a water-lubricated or grease-lubricated stern tube system. Factor 2 Second depending on the ship design the stern tube can be supported with struts or can be positioned within the ships hull. In Power propulsion and turbochargers.
With some 90 percent of the worlds shipping fleet using oil as a propeller shaft lubricant it might be hard to make the case that water lubrication is a better option. Nevertheless in todays operating climate water lubricated stern tube solutions are emerging as the sensible way to go. The stern tube is a sensitive part of the ship where the sea water can easily seep inside.
The stern glands thus seal the area between the stern tube and the propeller shaft. The glands are attached at the forward end of the stern tube and prevent the passing of sea water into the ship. The glands also prevent the leaking of oil from the stern bearings into the sea.
Seawater Lubricated Stern Tube. There are three types of stern tube bearing arrangements that are used to accomplish these goals. Stuffing boxes which uses packing material to seal the area 2.
Oil lubricated stern tube bearing system is applied. There are various kinds of seal systems used such as lip type or mechanical type for oil lubricated stern tubes. The basic function is to prevent oil leakage from and seawater penetration into the stern tube.
The most popular oil lubricated seal is a lip type seal and an example is shown in Fig.