ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Babbitt Bearing Lubrication Types and Systems

Updated on June 25, 2010

Babbitt Bearings

Made from special soft alloys, Babbitt bearings are rotary bearings consisting of a thin layer of Babbitt material, also known as white metal, deposited on a plain bearing housing. While the plain or journal bearing supports the rotating component, the Babbitt alloy layer mainly functions as a wear component that reduces friction between the journal and the bearing. In addition, this layer also helps in cushioning shells from hard rotating shafts. Babbitt materials usually comprise of tin, copper, antimony, or lead, combined in varied proportions, to create an alloy consisting of hard crystals dispersed in a matrix of soft alloys. Some applications of the Babbitt bearing include high-speed rotating equipment such as compressors, chillers, turbines, electric motors, gear drives, locomotives, marine, or pumps. There are several types of Babbitt bearings available, such as self-equalizing, sleeve, thrust, tapered, as well as tilting shoe bearings. Typically, this type of bearing requires a lubricant, such as spindle oil between SAE 10 to 70, supplied by a lubrication system.

Babbitt Bearing Lubrication Systems:

The types of lubrication systems can be categorized into three groups:

  • Bearings that require external application of lubricants
  • Self-lubricating bearings
  • Bearings made of materials that serve as a lubricant

While most of the bearings that require external lubricant application have a plain inner surface, some of them are grooved to help the lubricant enter the space between the bearing and journal. On the other hand, self-lubricating bearings have lubricants that are contained within the bearing walls. Most common sintered metal bearings have porous walls that draw oil by capillary action and the oil is released by pressure or application of heat. The last type of lubrication system consists of a solid one-piece metal bushing with eight-grooved channels, filled with graphite, on the ID.

Lubricant Properties:

The selection of a lubricant is primarily based on its properties. A good lubricant should ensure low friction, adhere to the bearing surface, and reduce wear. In addition, the lubricant must have good thermal stability and durability while removing excessive heat generated by friction. Antifoaming ability, corrosion protection, and a good cleaning effect on the bearing surface are some other desired properties of a good lubricant. Compatibility with seal materials is also desired.

Babbitt Bearing Lubrication Types:

Journal bearings can be lubricated by various methods and common classification of journal bearing lubrication types are:

  • Hydrodynamic or full-film condition
  • Boundary
  • Hydrostatic

Hydrodynamic Lubrication:

Hydrodynamic lubrication, which is also referred to as full film or thick film lubrication, involves the creation of a wedge-shaped zone between the journal bearing and the rotating shaft. The wedge-shaped formation generally occurs at high velocity, and consequently leads to the creation of a lubricant film between the bearing and journal. This film pushes the shaft up and supports its weight, creating a full-film condition that occurs when it carries the shaft load in entirety. The oil film is maintained by the rotation of the journal. As the journal rotates, heat is generated on the bearing surface by the shearing action of the oil film. To prevent thermal damage, cooling is improved by increasing the oil pressure and forcing greater amounts of oil into the bearing. In this type of lubrication, there is no contact between the two moving surfaces. Hydrodynamic lubrication can be performed by using oil or grease.

Boundary Lubrication:

Boundary lubrication is typically used when full-film lubrication is not possible. In boundary or mixed lubrication conditions, the shaft load is partially supported by the bearing, while the oil film between the two carries the remaining load. This type of lubrication occurs when not all the conditions for full-film lubrication are satisfied. The occasional contact between the moving surface results in bearing wear, which can be reduced by the inclusion of additives to the lubricant. In addition, surface treating the bearings also helps reduce wear.

Some of the conditions to be satisfied for both full-film and boundary lubricants include:

  • The condition in which a bearing runs is dependent on operating conditions, load, relative surface speed, clearance within bearing, quality and quantity of lubricant, as well as temperature.
  • If the bearing is not designed to run in the dry or boundary condition, it will wear out resulting in high coefficient of friction.

Hydrostatic Lubrication:

Hydrostatic lubrication is the process of using lubricating oil under pressure to create a separation between the two contact surfaces. This type of lubrication is typically used in applications where heavy loads are to be supported at speeds that are too low to use hydrodynamic lubrication. The bearings are lubricated by an external pump, which always maintains static amount of pressure. While hydrodynamic lubrication can use both grease and oil, this lubrication type can only use oil. An example of hydrostatic bearing is a heavily loaded bearing that is found in automobile engines, which usually feeds oil through a hole in the bearing. Hydrostatic lubrication has low deflections in particular load ranges, making it ideal for high precision machine tools. However, it is comparatively more complex and expensive than hydrodynamic lubrication systems.

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)