Bearings
Bearings are mechanical components that enable rotational or linear movement by reducing friction between moving parts. They are used in a wide range of applications, from machinery and vehicles to household appliances and industrial equipment. Bearings come in various types, including ball bearings, roller bearings, and plain bearings, each designed for specific load and speed requirements.
7 Key excerpts on "Bearings"
eBook - ePub- Dick Jeffrey(Author)
- 2013(Publication Date)
- Routledge(Publisher)
...Chapter 6 B EARINGS A bearing is a device which supports a rotating shaft or spindle or guides one component which slides over another. In addition to its supporting function, a bearing is designed to allow relative movement between two separate components to occur with the least possible frictional resistance. Almost all industrial mechanisms contain elements which require relative movement between contacting surfaces and therefore include some sort of bearing. In principle, Bearings fit into two main categories: Plain Bearings in which the surface of one component slides over the surface of another and where the surfaces in contact are specially prepared in order to minimise friction and wear. Rolling element Bearings in which a series of rolling elements, i.e. either balls or rollers of various shapes, are interposed between the two surfaces in order to facilitate movement of one with respect to the other. Rolling element Bearings are sometimes referred to as anti-friction Bearings because the relatively small contact area of the rolling elements helps to reduce, though not eliminate, the resistance to relative motion. Bearings can also be classified according to the type of function they perform: Journal Bearings which support a rotating shaft or spindle and confine radial motion as in Figs. 6-1a and 6-2a. Fig. 6-1 Examples of plain Bearings. Fig. 6-2 Examples of rolling element Bearings. Thrust Bearings which prevent axial motion of a shaft as in Figs. 6-1b and 6-2b. Linear Bearings which guide or support relative motion between components in a straight line as in Figs. 6-1c and 6-2c. The function a bearing performs is largely determined by the type of load that it has to carry. The type of load also determines the particular type of bearing selected...
eBook - ePub- Alan Hendrickson(Author)
- 2012(Publication Date)
- Routledge(Publisher)
...17 Bearings and Wheels DOI: 10.4324/9780080557540-17 Bearings Bearings are basic and essential components of all machinery. There are dozens of bearing types designed for optimum performance under different speeds, loads, environments, etc. Rotational Bearings, the most common type, allow one component to rotate relative to another. These Bearings must resist radial loads, which are forces perpendicular to the shaft’s axis, and thrust loads, which are forces parallel to the shaft’s axis. Thrust Bearings are a subset of rotational Bearings which are designed to take axial (thrust) loads only. Linear Bearings, the other major class of Bearings, are designed to optimize travel along the length of a shaft. All Bearings must offer as little frictional resistance to movement as possible to minimize drive power loss. Bearing nomenclature can be awkward and confusing. The term “bearing” can refer both to the device that allows the shaft to rotate with little friction, and to the whole assembly of that device in a mounting frame. For example, a pillow block can be referred to as a bearing, and it consists of a mounting frame that contains a bearing. In theatre machinery, it is unusual to need an unmounted bearing since most components we use have Bearings already designed in—gear reducers, motors, and pillow blocks, for example. Nonetheless we still need an understanding of Bearings to select an unmounted bearing when needed, or to select products with a bearing appropriate for the application. The loads that a particular bearing can withstand can only be determined from manufacturer’s ratings. Their catalogs usually have extensive engineering sections that present in great detail exactly what a particular bearing can and cannot do. The ratings usually list radial load capacity (in pounds, at a given RPM), appropriate ambient temperature, and hours of life. Thrust loads reduce radial capacity, but again only the manufacturer can state what capacity is allowed...
eBook - ePubManual of Engineering Drawing
British and International Standards
- Colin H. Simmons, Dennis E. Maguire, Neil Phelps(Authors)
- 2020(Publication Date)
- Butterworth-Heinemann(Publisher)
...35 Bearings and applied technology Abstract In a plain bearing, the relative motion is by sliding in contrast with the rolling motion of ball and roller Bearings. When surfaces rotate or slide, the rotational or sliding motion results in friction and heat. Energy is used, the surfaces wear, and this reduces component life and product efficiency. Friction may be reduced by lubrication which keeps the surfaces apart. At the same time, lubricants dissipate heat and maintain clean contact surfaces. Materials are carefully selected with appropriate mechanical and physical properties for Bearings and their housings, to minimize the effects of friction, and particular care is taken with the accuracy of machining, surface finish and maintenance of all component parts associated with Bearings. This chapter covers all types of Bearings from Plain to Ball and Roller to Thrust and includes good advice on bearing selection, materials, alignment, lubrication, loads, rigidity, speeds, mounting and dismounting, seals, application, and finally fits and tolerances. Keywords Bearings; Ball; Roller; Needle; Seals When surfaces rotate or slide, the rotational or sliding motion results in friction and heat. Energy is used, the surfaces wear, and this reduces component life and product efficiency. Friction may be reduced by lubrication which keeps the surfaces apart. At the same time, lubricants dissipate heat and maintain clean contact surfaces...
eBook - ePubManual of Engineering Drawing
Technical Product Specification and Documentation to British and International Standards
- Colin H. Simmons, Dennis E. Maguire(Authors)
- 2012(Publication Date)
- Butterworth-Heinemann(Publisher)
...Chapter 35 Bearings and Applied Technology When surfaces rotate or slide, the rotational or sliding motion results in friction and heat. Energy is used, the surfaces wear, and this reduces component life and product efficiency. Friction may be reduced by lubrication which keeps the surfaces apart. At the same time, lubricants dissipate heat and maintain clean contact surfaces. Materials are carefully selected with appropriate mechanical and physical properties for Bearings and their housings, to minimize the effects of friction, and particular care is taken with the accuracy of machining, surface finish and maintenance of all component parts associated with Bearings. In a plain bearing, the relative motion is by sliding in contrast with the rolling motion of ball and roller Bearings. Plain Bearings Plain Bearings may be classified as follows : The bearing metal should have a low coefficient of sliding friction, be able to conduct heat generated away from the bearing surfaces, resist wear in use and be tough enough to withstand shock loading in service. In the event of breakdown due to lack of lubrication, it may be desirable when overheating occurs for the bearing material to run, preventing seizure and possible severe damage to associated mechanical parts. Direct-lined Housings These housings are lined directly with bearing materials and the choice of material is limited by the practicality of keying or bonding the bearing material to the housing surface. The dimensions of the housings, casting temperatures and bonding characteristics of the bearing materials will determine whether metallurgical bonding is possible without unacceptable distortion of the housing. Generally this technique is limited to ferrous housings with low-melting point whitemetal bearing surfaces...
eBook - ePubManual of Engineering Drawing
Technical Product Specification and Documentation to British and International Standards
- Colin H. Simmons, Dennis E. Maguire(Authors)
- 2009(Publication Date)
- Butterworth-Heinemann(Publisher)
...Chapter 32. Bearings and applied technology When surfaces rotate or slide, the rotational or sliding motion results in friction and heat. Energy is used, the surfaces wear, and this reduces component life and product efficiency. Friction may be reduced by lubrication which keeps the surfaces apart. At the same time, lubricants dissipate heat and maintain clean contact surfaces. Materials are carefully selected with appropriate mechanical and physical properties for Bearings and their housings, to minimize the effects of friction, and particular care is taken with the accuracy of machining, surface finish and maintenance of all component parts associated with Bearings. In a plain bearing, the relative motion is by sliding in contrast with the rolling motion of ball and roller Bearings. Plain Bearings Plain Bearings may be classified as follows : The bearing metal should have a low coefficient of sliding friction, be able to conduct heat generated away from the bearing surfaces, resist wear in use and be tough enough to withstand shock loading in service. In the event of breakdown due to lack of lubrication, it may be desirable when overheating occurs for the bearing material to run, preventing seizure and possible severe damage to associated mechanical parts. Direct-lined housings These housings are lined directly with bearing materials and the choice of material is limited by the practicality of keying or bonding the bearing material to the housing surface. The dimensions of the housings, casting temperatures and bonding characteristics of the bearing materials will determine whether metallurgical bonding is possible without unacceptable distortion of the housing. Generally this technique is limited to ferrous housings with low-melting point whitemetal bearing surfaces...
eBook - ePubMechanical Engineering Design
Third Edition
- Ansel C. Ugural(Author)
- 2020(Publication Date)
- CRC Press(Publisher)
...10 Bearings and Lubrication 10.1 Introduction The goal of a bearing is to provide relative positioning and rotational freedom while transmitting a load between two parts, commonly a shaft and its housing. The object of lubrication is to reduce the friction, wear, and heating between two surfaces moving relative to each other. This is done by inserting a substance, called a lubricant, between the moving surfaces. The study of lubrication and the design of Bearings are concerned mainly with phenomena related to the oil film between the moving parts. Note that tribology may be defined as the study of the lubrication, friction, and wear of moving or stationary parts. The literature on this complex subject is voluminous. Much is collected in the CRC Handbook of Lubrication, sponsored by the American Society of Lubrication Engineers [ 1 ]. Also see [ 2 ]. The website www.machinedesign.com includes general information on Bearings and lubrication. There are two parts in this chapter. In Part A, the fundamentals of lubrication with particular emphasis on the design of journal (the so-called sleeve or sliding) Bearings is discussed. The basic forms of journal Bearings are simple. In Part B, the concern is with rolling Bearings, also known as rolling-element Bearings, and anti-friction Bearings. We describe the most common types of rolling Bearings, bearing dimensions, bearing load, and bearing life. There is also a brief discussion on materials, mounting, and lubricants of rolling Bearings. Rolling-element Bearings are employed to transfer the main load through elements in rolling contact, and they have been brought to their present state of perfection only after a long period of development. Either ball Bearings or roller Bearings, they are made by all major bearing manufacturers worldwide. Part A: Lubrication and Journal Bearings Journal Bearings support loads perpendicular to the shaft axis by pressure developed in the liquid...
- Barbara Renner(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
...The smooth surface is designed to reduce the amount of friction between the rotating objects. The bearing also provides an area where a lubricant can be applied, further reducing friction and increasing the life of the rotating elements. Figure 4.2. A vertically mounted centifugal pump 4.11 A bearing also distributes the load from the shaft to the bearing housing and support structure. The distribution of the load depends on the type of bearing used. For example, plain style Bearings (bronze or sleeve type) support the load at only one point. Antifriction Bearings, on the other hand, have a number of balls or roller contact points that distribute the load within the bottom part of the housing at approximately a 120° angle (Figure 4.3). 4.12 Another bearing function is to keep the rotating elements in place. This is especially important for speed reducers and other gear-driven applications where the machined teeth must be kept at a proper distance and in line to provide a smooth transfer of motion and energy. It is just as important for alignment of any chain-driven components, even though the tolerances might not be thought of as critical. BEARING CATEGORIES 4.13 Bearings can be classified into two main categories—plain and antifriction. Grouping the Bearings in these two categories classifies them by construction rather than by any other means of identification. Antifriction Bearings may further be subdivided into construction categories of ball, roller, and needle. 4.14 All Bearings, plain or antifriction, can be further subdivided into the major categories of journal Bearings—those that support rotating shafts; thrust Bearings—those that restrain axial movement and take horizontal loads; and guide or slipper Bearings—those used to support sliding components. In some applications, journal and thrust Bearings will be combined into a single unit. This will be further discussed as the Bearings are described in more detail...
