When you research ball bearings in depth, you quickly find out: A) that SKF is one of the top names in the field, and B) that the SKF Bearing Cross Reference is helpful to track down just the bearing you need. Whether it’s to be used in an automotive context or you’re looking for an SKF bearing puller, the cross reference makes finding the right thing faster and easier.
Using The SKF Bearing Cross Reference
The SKF Bearing Cross Reference is created to provide designers and engineers with comprehensive data, information, and details regarding ball bearings. In the cross reference there is page after page after page of technical information on bearings, plus tables of everything available. It is, in essence, a bearing selector that helps you find the right bearing for each application. In the resource, bearing part numbering systems are all cross-referenced between many different manufacturers. This allows you to see how an SKF part will correspond with those of other manufacturers, for example Ina bearings or Mcgill needle bearings.
The information contained in the SKF Bearing Cross Reference is both technical and essential. Drive ring and bearing designs can often both be totally and completely customized. From the simplest of flanges and intricate lubrication graves to O-ring housings to brand new designs and materials, exact information is needed to get the exact right part.
- As an example, if an extreme fit is unsuitable, then you can use another grouping of coded bores that are similarly graded in their housing and shaft diameters. This is a more economical approach than reducing diameter tolerance.
- Ball bearings are normally made to standard precision-grades and with set tolerances for geometric accuracy and size.
- The standards are called ABEC classes and are established by, of course, ABEC (the Annular Bearing Engineers Committee.)
- The standards are also accepted by ANSI (the American National Standards Institute) as well as by the International Organization of Standards.
- These standards serve as a core part of the Bearing Cross Reference.
Aside from the standard ABEC tolerance that describes most ball bearing attributes, the outer ring’s outer diameter and the bore of the inner ring may be coded to specific requirements. This helps keep a consistent line-to-line fit. Miniature ball bearings and instrument ball bearings outer and inner diameters can further be calibrated to quite specific ranges by setting their appropriate dimensional codes.
The SKF Bearing Cross Reference primarily includes three parts:
- Ball Bearing references
- Roller Bearing references
- Thrust references
To see how this works, let’s consider the Thrust National Bearing Cross References. In it would be found this information:
- Cylinder Thrust Roller Bearings, i.e., thrust bearings which contain cylinder-shaped rollers. They’ll only sustain axial loads; however, they’re ideal for larger and heavier loads. They have a higher axial rigidity and have cages that are made of brass.
- Tapered thrust bearings. These thrust bearings contain tapered rollers (as the name suggests). Located on the outside of the housing washer of the TT-bearings is a very important “rib.” This rib directs the shaft accurately in the right direction. A TTF bearing, on the other hand, does not have a rib and are able to tolerate a lot of eccentric quirks while operating.
- Thrust ball bearings are specifically made to carry thrust loads as they operate at high velocity. You can order these with a washer and seat that are properly aligned if deflection or misalignment can’t be avoided.
- A spherical thrust bearing is made to handle quite heavy and large thrust loads, carrying them in a single direction as they operate at a low or moderately low speed. Their design allows for some limited radial load. The sphere-like shape of their outside ring raceway makes them ideal for correcting misalignment.
That last paragraph is just one example of the type of information that is available via the SKF Bearing Cross Reference. Along with a catalog of bearings, it really is quite indispensable for matching up the right SKF bearings for precisely the right task.
Ball Bearing Interchange
The ball bearing interchange involves the selection and use of dimensionally equivalent ball bearings. To select bearings, you will need to consult an interchange table. But to make the best use of this guide, you’ll first need to know something about the different kinds of bearings themselves. There are several different kinds used, each with advantages and disadvantages. Each is used for different reasons and in different contexts.
- Ball Bearing – The first type we call simply a ball bearing. As the name suggests, it uses a ball to move and rotate the load. Ball bearings are not as expensive as other bearings like cylinders. They also have a higher accuracy. Ball bearings generally don’t have as much friction when moving lighter loads. They support both axial and radial loads (An axial load is parallel to the shift, while a radial load is perpendicular).
- Roller Bearing – A roller bearing uses cylinders rather than balls, and usually has a larger diameter. Roller bearings are good for supporting higher-capacity loads, but they also often have more friction with axial loads. Most commonly, roller bearings are used in machinery and rotary appliances.
- Thrust Ball Bearing – Thrust ball bearings consist of two steel washers and balls that are positioned within them. They’re typically used in low-speed appliances. Usually they can’t handle heavy loads. A couple of examples: you can find thrust ball bearings used in turn tables and swivel bar stools.
- Tapered Roller Bearing – A tapered roller bearing is used to support bigger radial and thrust loads. This bearing consists of a series of conical or tapered rollers held in a cage in between the outer and inner bearing tracks. They’re often used in car hubs. A major disadvantage to taper roller bearings is the high cost–and the fact that they tend to add more friction than with a regular ball bearing.
- Needle Bearing – A needle bearing is similar to a roller bearing except the cylinders are skinnier and longer (hence the name “needle”). These are frequently used when a reduced friction of the rotating surface is needed. Some specific applications include engines and engine parts, like needle bearings for tractors, as well as auto transmissions. In addition, there are eight or more needle bearings in a rear-wheel drive car’s drive shaft.
The Bearing Interchange Table
The bearing interchange table will allow you to select the part number, dimension, or bearing type you are using. You will then select the exact series and manufacture for a compatible bearing. Further details include internal clearances and tolerances for selected bearings.
For the majority of applications, you will be selecting from standard bearing choices. Standard bearings are produced in large volume and generally used worldwide. This will basically guarantee the availability of a compatible bearing for your project.
However, as you study the international bearing interchange or the sealed roller bearing interchange, keep in mind that different bearing types reach into the millions. You will want to take the time to make sure you understand how to use the interchange table correctly. In some cases, there are brief tutorials available that offer instructions and tips, and this will be worth the time if you are a first time user or you don’t have an engineering background.
The bearing interchange is ultimately just a tool to help you get the best bearings for your purpose. You’ll still need to make right choices, such buying only from respected manufacturers like Timken or Fafnir bearings. Even the best tool, after all, is limited to the common sense of the user.