Cylindrical Roller Bearings: Types (N, NU, NJ) & Cages

The main difference between cylindrical roller bearing types lies in the arrangement of the flanges (ribs) on the inner and outer rings. This structure determines whether the bearing can carry axial loads (thrust) in addition to radial loads.

NU Series (No Inner Ribs):
Features double ribs on the outer ring and no ribs on the inner ring. The inner ring can be removed, allowing for easy mounting and dismounting. Ideal for carrying heavy radial loads where thermal expansion of the shaft is expected (non-locating bearing).
N Series (No Outer Ribs):
Features double ribs on the inner ring and no ribs on the outer ring. Like the NU series, it permits axial displacement between the shaft and housing, making it a perfect floating bearing choice.
NJ Series (Single Direction Axial Load):
Has double ribs on the outer ring and a single rib on the inner ring. This design allows the bearing to support heavy radial loads and carry axial loads in one direction, guiding the shaft axially.
NUP Series (Locating Bearing):
Features double ribs on the outer ring, one fixed rib on the inner ring, and a separate loose rib washer. This allows the bearing to carry axial loads in both directions, functioning as a locating bearing to fix the shaft position.

Series Type	Configuration (Ribs)	Axial Load Capacity	Typical Application
NU Series	2 Outer / 0 Inner	None (Allows expansion)	Floating bearing end
N Series	0 Outer / 2 Inner	None (Allows expansion)	Floating bearing end
NJ Series	2 Outer / 1 Inner	One Direction	Shaft guidance (1-way)
NUP Series	2 Outer / 1 Inner + Ring	Both Directions	Locating bearing (Fixed)

The N, NU, and NJ series have critical differences in installation and axial load handling. If you are selecting a bearing for a specific motor or gearbox, check out our detailed engineering guide: 【Difference Between N, NU, NJ & NUP Series】

Cylindrical Roller Bearing: What Is It?

Defining Cylindrical Roller Bearings and How They Work

Bearings are essential parts of equipment because they guarantee smooth relative motion and lower friction between moving parts. Because of their dependability and versatility, rolling bearings are the most widely used type of bearing. The cylindrical roller bearing is a particular type of rolling bearing that is notable for its capacity to support heavy radial loads. The cylindrical rolling components of cylindrical roller bearings are their defining feature. The load-bearing capability of these bearings is increased by using line contact between the rollers and the raceways. Although they are not the best at handling axial stresses, their special design allows them to successfully handle large radial loads. Cylindrical roller bearings have larger contact surface areas than ball bearings, which results in increased load capacity, enhanced stiffness, and superior shock resistance.

Key parts of cylindrical roller bearings explained, including out ring, inner ring, rollers, and cage. — Key-parts-of-cylindrical-roller-bearings-explained

Differences from other types of bearings

Cylindrical roller bearings are superior to ball bearings at managing heavy loads and high-speed operations, which makes them perfect for heavy-duty equipment. Ball bearings, on the other hand, work well under light loads and when exact placement is needed. The needle roller bearing is another significant member of the roller bearing family. The rollers in these bearings resemble needles and have a smaller diameter than cylindrical rollers. They are ideal for usage in small areas due to their low cross-sectional height, which helps to make machinery lighter and more compact. Tapered roller bearings are the recommended option for applications requiring the simultaneous handling of axial and radial loads. Conical rollers, which are used in these bearings, effectively control both axial and radial loads in a single direction. Spherical roller bearings are the best at handling misalignment and large loads. These bearings, which include barrel-shaped rollers, enable the cage, rolling elements, and inner ring to rotate at an angle to the outer ring. Because of this feature, spherical roller bearings are essential for machines that are subject to shaft deflection or heavy loads.

How Do Cylindrical Roller Bearings Operate?

Interaction Between Racetracks and Rollers

The unique feature of cylindrical roller bearings is their line contact design, which happens as the rollers travel down the raceways. Compared to point contact, this kind of contact produces a wider contact area because it involves the interaction of a flat surface with a cylindrical surface. With our high-end cylindrical roller bearings, we aim to provide a solution tailored to your industry’s needs. Savor unparalleled brilliance and performance. Because of these characteristics, cylindrical roller bearings with line contact are ideal for demanding applications like high-speed operations or extended use under difficult circumstances. They are a fantastic option for sectors looking for the best performance in high-stress situations because of their dependability and durability.

Cylindrical Roller Bearings Working Mechanism — how-cylindrical-roller-bearings-work

Roles of the Inner and Outer Rings

The outer ring of a cylindrical roller bearing is usually fixed to the housing, whereas the inner ring is usually attached to the spinning shaft. These two parts work together to give the bearing its functionality. It is essential to align the inner and outer races with the shaft and housing before fitting the bearing into its housing; this will decrease friction and prevent the bearing from wearing out too quickly. Because of this balanced state formed by the harmonious interaction, complicated equipment can work perfectly even when things go wrong. In order to work reliably and efficiently, this architecture is mostly used in big industrial machines and power transmission networks.

Design Principles for Efficient Support

Optimizing load distribution, minimizing frictional energy loss, and increasing stiffness are the primary objectives of cylindrical roller bearing design. The ratio of roller length to raceway width is carefully determined to keep these factors in balance. This makes sure that the bearings work perfectly even when they are under a lot of stress. A lot of the time, these bearings come with lubricating holes and seals that make them work even better. Over time, these features keep the performance stable and help heat escape.

Cylindrical Roller Bearings’ Advantages

Cylindrical roller bearings are real workhorses in the world of machinery. They stand out because of their ability to handle heavy loads, their durability, and their adaptability across different industries. Let’s break down their key advantages into an easy-to-read table:

Advantage	Description
High Load Capacity	Thanks to their line contact design, cylindrical rollers can handle large radial loads with ease. This makes them perfect for heavy machinery like gearboxes, wind turbines, and pressure-intensive applications.
Sturdiness and Lifespan	The line contact distributes radial loads evenly, reducing stress and fatigue damage. This ensures better durability and longer lifespan compared to point contact designs.
Versatile Applications	Whether it’s electric motors, rail systems, or vehicle transmissions, cylindrical roller bearings excel. They can also handle heat, vibrations, and work well in both lubricated and dry conditions, making them incredibly adaptable.

Applications of Cylindrical Roller Bearings

Cylindrical roller bearings come in various types designed for specific applications. Whether it’s industrial machinery, automotive components, or heavy load equipment, the right bearing type ensures maximum performance and reliability. Here’s a detailed table that includes commonly used bearing types for each application:

Application Area	Description
Industrial Machinery	Ideal for large or fast-spinning shafts in conveyor systems, pumps, and compressors. Commonly used types include NU and N designs for high-speed applications and NJ types for axial load support in energy, paper, and steel industries.
Automotive Components	Found in wheel axles and differentials, ensuring smooth rotation and torque management. Frequently used models include NUP designs for axial positioning and RN series for compact designs that handle high stress.
Heavy Load Equipment	Essential for heavy-duty machines like cranes and mining equipment. NN and NNU series are often used due to their high radial load capacity and ability to handle impact and vibration in harsh environments like lifting systems.

Cylindrical Roller Bearings’ Salient Characteristics

Extremely Accurate

Because of their remarkable accuracy tolerances, cylindrical roller bearings are essential for use in robotics, aeronautical engineering, and precision manufacturing. The rolling elements and raceways are consistently aligned, which minimizes operational variations and lowers noise and vibration. In processes like metalworking and semiconductor fabrication, this high degree of precision immediately improves the machinery’s overall accuracy and raises the quality of outputs. They are perfect for applications needing both great rotational accuracy and stability because of their exact manufacture, which also allows for smooth operation at high speeds.

Minimal Friction

Additionally, because they produce less heat and friction, cylindrical roller bearings are designed for maximum efficiency. When the cylindrical rollers are properly lubricated, their rolling action reduces friction while in use. In addition to lowering heat production, this friction reduction increases the bearing’s longevity. Reduced heat production also means less energy loss, which raises the machinery’s total efficiency. Additionally, reduced friction results in quieter operation, which makes it possible for the bearings to run more smoothly and silently—a critical feature in areas where noise is a concern.

Resistance to Temperature

One of the best things about cylindrical roller bearings is that they can handle big changes in temperature. Therefore, they excel in high-temperature applications such as turbines, industrial furnaces, and metallurgy. Heat-resistant materials, sophisticated coatings, and precisely mixed lubricants are used to accomplish this heat resistance, which guarantees stability and less wear even in extremely hot environments. These bearings maintain their accuracy and structural integrity in spite of the difficulties caused by temperature expansion and contraction, guaranteeing dependable and constant performance.

Cylindrical Roller Bearing Cages: Brass vs. Steel vs. Polyamide

Selecting the right cage (separator) material is just as important as choosing the bearing type. The cage guides the rollers and determines the bearing’s suitability for speed, vibration, and temperature limits. Here are the three most common materials and their specific codes:

Pressed Steel (Suffix J)

This is the standard cage for most general-purpose applications. Pressed steel cages are lightweight and provide plenty of space for lubricant to circulate. They are cost-effective and suitable for normal operating temperatures and moderate speeds. However, they are less resistant to shock loads compared to brass.

Machined Brass (Suffix M/EM)

For heavy-duty applications, machined brass is the gold standard. Brass cages are exceptionally robust and can withstand high vibration, heavy acceleration, and shock loads that would destroy a steel cage. They are commonly found in large-sized bearings used in mining, crushing, and vibrating screens. While more expensive, they offer the highest reliability in harsh environments.

Polyamide / Nylon (Suffix TVP/ET)

Polyamide 66 (fiberglass reinforced) cages are becoming increasingly popular for small to medium-sized bearings. They are extremely lightweight, offering the lowest friction and quietest operation, making them ideal for high-speed motors. However, they have a temperature limit (usually up to 120°C/250°F). They should not be used in vacuum environments or with certain synthetic lubricants that can degrade the plastic.

Conclusion

Cylindrical roller bearings are the backbone of heavy-duty machinery, offering unmatched radial load capacity. However, long-term performance depends on selecting the right configuration (NU, N, NJ, or NUP) and the correct cage material for your operating temperature.

At TFL Bearing, we don’t just sell parts; we help you engineer solutions. Whether you need a high-speed polyamide cage or a vibration-resistant brass design, our engineers are ready to assist. [View Our Full Cylindrical Roller Bearing Catalog] or [Contact Us] for a custom quote today.

Frequently Asked Questions

What is the purpose of cylindrical roller bearings?

In order to provide smooth, effective operation in a variety of industries, cylindrical roller bearings are mostly employed to handle heavy machinery and large radial loads. They are frequently used in heavy-duty machinery, pumps, conveyor systems, automobile transmissions, and other applications where their robustness and large load capacity are crucial.

Can cylindrical roller bearings handle axial (thrust) loads?

Standard types like NU and N series cannot handle any axial load; they only support radial loads and allow for thermal expansion. However, NJ and NUP types are designed with flanges (ribs) that can manage limited axial loads in one or both directions. For heavy axial loads, Tapered Roller Bearings are usually a better choice.

What distinguishes ball bearings from roller bearings?

The type of rolling element utilized is the primary distinction between ball and roller bearings. Cylindrical rollers, used in roller bearings, have a greater contact surface and are perfect for supporting huge radial loads. Ball bearings, on the other hand, are more appropriate for lesser weights and faster speeds. They use spherical balls that can withstand both axial and radial loads.

Are cylindrical roller bearings interchangeable?

Generally, the inner and outer rings of separable cylindrical roller bearings (like NU and N series) are interchangeable if they share the same ISO dimension series and tolerance class. However, mixing components from different manufacturers is not recommended due to subtle differences in internal clearances and roller profiles, which can lead to reduced lifespan.

What causes cylindrical roller bearings to fail prematurely?

The most common causes include improper lubrication, contamination, and misalignment. specifically for cylindrical rollers, “skidding” (sliding of rollers instead of rolling) can occur if the bearing is too lightly loaded at high speeds. Ensuring the minimum load requirement is met is crucial to prevent this unique failure mode.

Cylindrical Roller Bearing: What Is It?

Quick Guide: Types of Cylindrical Roller Bearings (N, NU, NJ, NUP)

Cylindrical Roller Bearing: What Is It?