Stern Tube

 Tumala,  Tumala, John Rey Rey R. BSMar E-III Bravo

August 13, @01 E!"R. "anas

Stern Tube The stern tube of a ship has a peculiar shape and arra arrang ngem emen entt for for carr carryi ying ng the the prop propel elle lerr shaf shaft. t. Streamlined at the aft end, there is very little space to accommod accommodate ate the propelle propellerr shaft shaft arrange arrangemen ment. t. The stern tube is situated at the aft peak of the ship’s hull hull and and the prope propelle llerr shaft shaft arran arrange gemen mentt is also also situated at the same level. The forward end of the stern tube is supported by the aft peak bulk head and the aft end of the stern tube gets its support from the stern frame of the ship. Throughout the length, the shaft is supported by specially designed brackets and narrow floors inside the stern tube. Stern tube bearing The total weight of the propeller shaft inside the stern tube is carried by the bearing known as the stern tube. The weight of the overall stern tube arrangement, along with the bearings is carried by the stern frame and the internal framing of the ship’s hull hull struc structu ture re at the stern stern tube tube for for suppo supporti rting ng the the shaft, located at both the ends. The main function of  stern tube bearing is to allow an unrestricted and smooth rotation of the propeller shaft.

Shaft seal

Shaft seals on pumps, compressors, turbines, and other rotating equipment not only retain the bearing lubr lubric ican ants ts but but also also prot protec ectt them them from from exte extern rnal al contaminants. contaminants. Both contact lip seals and noncontact noncontact bearing isolators can serve this purpose. The best solution for a given application depends largely on service conditions, desired performance, and value, or cost plus delivered performance. !ontact lip seals are available in a variety of materials, si"es, and configurations. #ade of elastomers molded into engineered angles and contours, these seals act as micro

hydrodynamic wedges that raise the lip and recirculate lubricant to form a thin meniscus of oil on which the seal rides. This hydrodynamic action reduces friction between the lip and shaft.

Aft Bearing

 $ft stern tube bearing wear pattern indicated that the bearing was supporting the shaft at the aft and forward ends, and not at all in the middle.

Plummer Blocks %lummer block housings can be used with highcapacity spherical roller bearings or selfaligning ball bearings. They are manufactured from highstrength cast iron as standard but are also available in cast steel or  spheroidal graphite cast iron. The housings have a re lubrication facility and can be used with either oil or lubrication.

grease

Thrust Bearings  $ thrust bearing is a particular type of rotary bearing. &ike other rotary bearings they permit rotation between parts, but they are designed to support a high axial load while doing this 'parallel to the shaft(. )ifferent kinds of thrust bearings are used to support different amounts of  axial load. Thrust ball bearings are used in applications that use little axial load, where a ring supports ball bearings. Spherical roller thrust bearings are used in applications that require high

axial load, and can also support shafts that are out of  alignment. Thrust bearings are used in higher speed applications that require oil lubrication, such as in the automotive and aerospace industries. *enerally, thrust bearings are composed of two washers 'raceways( in which those for ball bearings may be grooved, and the rolling elements.