Stave bearing

A stave bearing is a simple journal bearing where a shaft rotates in a bearing housing. Rather than the usual arrangement where the fixed part of the bearing surrounds most of the circumference of the shaft in one or two pieces, a stave bearing uses a large number of axial staves to support the shaft. A large housing is made with grooves running along the shaft, these grooves being filled with strips of suitable material, originally wood.

Uses

Stave bearings have long been associated with ships and their propeller shafts. The bearing is suitable for slow speeds and high loads. When used on ships, the bearing is designed to run immersed in water, allowing its use outboard of the stern gland or stuffing box.

Stave bearings are also well suited to applications such as rudder shafts, where rotation is intermittent and reciprocating, rather than continuous and unidirectional. Other bearing types, such as some ball bearings, don't perform well under this type of use and may fail prematurely.

Materials

The staves must resist the forces in the bearing and offer adequate lubrication from this water alone. They must also survive long-term immersion without rotting, softening or swelling. The historical material for this was the tropical hardwood timber, lignum vitae. In modern practice, Tufnol is often used.^[1] Recent developments in composites have seen polyester resin and phenolic resin composites such as Maritex and Orkot being used.

Nitrile rubber and UHMW-polyethylene have also been used.^[2][3] The tradename "Cutless" is used for these rubber bearings and this name has also, along with its mis-spelling 'Cutlass', become a generic term for them.^[4]

Where used on small boats, the bearing is often moulded in one cylindrical piece of rubber, although the inner surface is grooved so that it still functions as a stave bearing. Although small, these rubber bearings are still capable of handling a high power, even a 2,350 hp record-breaker like Bluebird K4.^[5]

The use of non-metallic bearing materials may also simplify problems with electrolytic corrosion between shaft and housing.

Cooling

Although immersion alone is often sufficient to lubricate the bearing, additional cooling and also flushing away of any gritty particles that could damage may be achieved on large ships by a pumped flow of water to the inboard end of the bearing. This flow passes along grooves in the bearing surface, leading outboard. A low pressure of around 5 psi is adequate.^[1]

References

1. ^ ^{a b} "Stave type bearings for marine applications". Tufnol. http://www.tufnol.com/tufnol/default.asp?id=99. 
2. ^ "Water-Lubricated Bearings and Shaft Sealing Systems". Duramax Marine. http://www.naval-technology.com/contractors/bearings/duramax/. 
3. ^ US 4149761 
4. ^ "Propeller Shaft Bearings: MarineEngineDigest.com". http://www.marineenginedigest.com/specialreports/cutless-bearings.htm. Retrieved 2011-10-25. 
5. ^ Tremayne, David (2005). Donald Campbell: The Man Behind the Mask. Bantam Books. ISBN 0553815113. 

This article about a mechanical engineering topic is a stub. You can help Wikipedia by expanding it.v · Categories: Bearings Marine propulsion Mechanical engineering stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем сделать НИР Seo Deok-Kyu I'm So Paid Look at other dictionaries: Stave — can refer to:*Staff (music), a set of five horizontal lines and four spaces used in musical notation *Stave church, a Medieval wooden church with post and beam construction prevalent in Norway *The individual wood strips that form the sides of a… …   Wikipedia Stave church — A stave church is a medieval wooden church with a post and beam construction related to timber framing. The wall frames are filled with vertical planks. The load bearing posts ( stafr in Old Norse) have lent their name to the building technique.… …   Wikipedia Flesberg stave church — (Flesberg stavkirke) is a stave church located in Flesberg, Numedal in Norway. It was probably built around 1200 A.D. The first written reference to the church is from 1359. The church was originally a single nave church ( type B ) with four free …   Wikipedia Cutlass (disambiguation) — Cutlass may refer to: Cutlass (short film) short film from 2007 directed by Kate Hudson Cutlass a type of sword Machete in some Caribbean countries. the Oldsmobile Cutlass, a car built by Oldsmobile Kutless, a band the USS Cutlass (SS 478), a… …   Wikipedia Thrust block — A thrust block is a specialised form of thrust bearing used in ships, to resist the thrust of the propellor shaft and transmit it to the hull. Early thrust boxes Early screw propelled steamships used a thrust block or thrust box composed of… …   Wikipedia Architecture of Norway — Storage …   Wikipedia building construction — Techniques and industry involved in the assembly and erection of structures. Early humans built primarily for shelter, using simple methods. Building materials came from the land, and fabrication was dictated by the limits of the materials and… …   Universalium Post church — A post church is a church building which predates the stave churches and differ in that the corner posts do not reside on a sill but instead have posts dug into the earth. Posts are the vertical, roof bearing timbers that were placed in the… …   Wikipedia Palisade church — A palisade church is a church building which is built with palisade walls , standing split logs of timber, rammed into the ground, set in gravel or resting on a sill. The palisade walls forms an integral part of the load bearing… …   Wikipedia Glossary of nautical terms — This is a glossary of nautical terms; some remain current, many date from the 17th 19th century. See also Wiktionary s nautical terms, Category:Nautical terms, and Nautical metaphors in English. Contents: A B C D E F G H I J K L M N O P Q R …   Wikipedia 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”