A Simple Guide to Roller Bearings

● What Are Roller Bearings?

● Why Use Roller Bearings?

● How Do Roller-Element Bearings Work?

What Are Roller Bearings?

Also known as roller-element bearings, roller bearings work under the same principle as ball bearings and serve one primary function: carrying loads with minimum friction. The difference between ball and roller bearings is shape and construction. The former use balls, while the latter use cylinders.

Roller-element bearings contain single or double rows of rollers. For instance, double-row roller bearings significantly improve radial load-carrying. Besides, the utility of these bearings in various shapes and sizes allow for transmissions of both radial and axial loads with reduced friction.

Why Use Roller Bearings?

The primary reason for using roller bearings is to reduce friction for effortless applications. As a result, they produce less heat during operation and alleviate the need for repetitive lubrication. Other advantages of using roller-element bearings include:

● Reduces maintenance and servicing costs

● Separable design, enabling for straightforward mounting and dismounting

● Interchangeable procedure – users can easily exchange the inner ring

● Bearings can facilitate change in direction without technical modifications

● Allows for axial displacement

How Do Roller-Element Bearings Work?

To appreciate how roller-element bearings function, first, it would be best to understand their design. A bearing may contain balls, ball rollers,

tapered rollers, or needle rollers. They feature an inner and outer ring with raceways for the caged parts. They also include a lubricant to reduce friction and seals to prevent the entry of particles that might contaminate the oil.

The pockets within the cages separate the rolling elements and maintain constant spacing as the apparatuses roll in the race tracks. As aforementioned, roller bearings come in different configurations, including single- and double-row elements.

The cylinders between the inner and outer races enable the caged elements to roll in the raceways along a single axis. The rolling elements would slide out of position under operation without the cages, causing bearing failure. The cages don't handle any loads, and their purpose is to hold the rollers in place. There are also cage-free bearings called full complementary bearings (FCB). Usually, FCBs have more rolling elements, handling heavier loads. Another upside is that they can withstand sudden shock loads as the rollers evenly distribute the load throughout the raceway.

There's also a need to lubricate roller bearings. Whether or not to grease depends on the product you buy. Sealed roller bearings typically come pre-lubricated, and no additional greasing is required. Non-sealed ones need a lubrication plan called elastohydrodynamic lubrication and must adhere to the manufacturer's specifications.

In this greasing regimen, a lubricant, usually less than one micron, is applied with pressure levels reaching up to 500,000 pounds per square inch. The grease partially solidifies and elastically deforms the rolling elements and the contact surface. Any contamination of the oil can lead to significant degradation of the mating surface and can result in the build-up of more wear particles.

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