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A Bearing is an item that allows constrained relative motion for two or more parts, usually rotation or linear in motion. Bearings are sometimes classified by the motions they allow, the principal of operation or the direction of loads they can tolerate.

Types of Bearings

There are several types of bearings, each used for specific purposes. We will be looking at Bearings that are used in Motorsports. These include ball bearings, roller bearings, roller thrust bearings and tapered roller thrust bearings.  These are primarily used in the drivetrain (transmission, rear axle, etc.) and wheels.  The engine primarily uses journal bearings, but some small engines (like motorcycles) use roller  bearings in the engine.

Ball Bearings

Ball Bearing
Ball Bearing - Image courtesy of bearingreviews-online.info
Ball Bearings are commonly used in the vehicle. They are found in everything from the Alternator to the Rear End. This type of bearing can handle both radial and thrust loads and are typically found in situations where the load is relatively small.

A ball bearing uses spheres that are in between the outer race and the inner race. These spheres only contact the inner and outer races at very small points which helps them spin very smoothly. But this also means that the spheres have a very small contact area holding the load and therefore overloading the bearings can deform or squish the balls, ruining the bearings.

Roller Bearings

Roller Bearing
Roller Bearing - Image courtesy of bearing-manufacturers.com
Roller Bearings use cylinders instead of balls to increase the load area to a line instead of a point. By doing this, these bearings can handle greater loads than ball bearings but cannot handle as much thrust loads.

There is also a variation of this type of bearing known as a needle bearing. The cylinders of these types of bearings have a very small diameter and therefore fit into tight places.

Roller Thrust Bearing

Roller Bearing
Roller Thrust Bearing - Image courtesy of bearing-manufacturers.com
Roller Thrust Bearings are mostly used in the Transmission between the gears. The gears used in the Transmission are helical with aligned teeth and this causes a thrust load that must be supported by a bearing.

Throw Out Bearing
Throw Out Bearing - Image courtesy of streettunedmotorsports.com
This type of bearing is also used in the bell housing between the engine and transmission. They are called Throw Out Bearings.

Tapered Roller Bearings

Tapered Roller Bearing
Tapered Roller Bearing - Image courtesy of sz-wholesale.com
Tapered roller bearings are used in car and truck hubs because they can support large radial and large thrust loads. They are usually mounted in pairs facing opposite directions so that they can handle thrust in both directions.

Journal Bearings

Journal Bearing
Journal Bearing - Image courtesy of steelwater.ca
Journal Bearings, sometimes called friction bearings are simple bearings in which the crankshaft (Journal) rotates in the bearing with a layer of oil separating the two parts. These bearings are usually used inside engines, and are surprisingly efficient when the engine is at operating RPM with good oil pressure. These bearings do not work well at very low RPM.  Low RPM conditions include the very short time that it takes the engine to start, or if you lug the engine at a very low RPM. Some engines (usually motorcycle engines) use ball bearings instead of Journal bearings.

Note on Bearings

Like with most things, bearings are designed with trade offs in mind.  Large bearings are durable, but cost more and have higher drag.  To gain fuel economy, the automobile manufacturers have been reducing the size of all bearings.  However, reduce them too much and now you have durability problems.  The same is true in racing, smaller bearings do not absorb as much HP, but are less durable. 


Programs that take Bearings into account:

Our Engine Analyzer Pro v3.9 program can take the drag of bearings into account to give you a more accurate simulation of what your engines output will be. Our Engine Analyzer v3.2, Engine Analyzer Plus v3.2 only take Accessory Loads into account.

And our Engine Log Book will catalog the sizes and part numbers of the bearings that you use inside your engine.

Plus our Drag Race Analyzer, Drag Race Analyzer Pro and Fuel Economy Calculator don't directly take bearings into account but you can change the driveline efficiency which does take friction and drag into account.

Our Circle Track Analyzer allows you to select the Transmission type and Rear Axle type that you are using in your vehicle. By changing the type of these it will change the drive line efficiency. This determines that the smaller the bearings the less friction (but smaller bearings are less durable) and the bigger the bearings the more drag and friction in the driveline.