Product Introduction

N Type Cylindrical Roller Bearings is the most basic model among single-row Cylindrical Roller Bearings. Its defining characteristic is that the inner ring features integral flanges on both sides, while the outer ring has no flanges. The bearing consists of an inner ring, cylindrical rollers, a cage, and an outer ring; the inner ring retains the rollers and cage via its flanges, forming a separable inner ring assembly, whereas the outer ring is a smooth, unflanged ring.

This configuration makes the N-type bearing a typical "floating bearing." Because the outer ring lacks retaining flanges, the inner ring assembly can move freely in the axial direction relative to the outer ring; consequently, N-type bearings can accommodate radial loads but cannot support axial loads. In shaft system design, they are typically positioned at one end of the shaft to serve as the floating end, compensating for thermal expansion caused by temperature increases during operation.

Structural Features

During operation, the cylindrical rollers undergo pure rolling motion between the inner and outer ring raceways, converting sliding friction between the shaft and the housing into rolling friction. The contact between the rollers and raceways is linear—unlike the point contact found in deep-groove Ball Bearings. This linear contact distributes the load evenly along the length of the rollers; therefore, for a given size, the radial load-carrying capacity of an N-type bearing is significantly higher than that of a ball bearing—typically 1.5 to 3 times that of a deep-groove ball bearing of the same dimensions.

The flanges on both sides of the inner ring serve two purposes: first, they guide the roller ends to prevent tilting during operation; second, they retain the rollers and cage on the inner ring, allowing the inner ring assembly to be handled as a single unit. The absence of flanges on the outer ring means there is no axial constraint between the inner and outer rings; when the shaft expands due to heat, the inner ring (along with the rollers) can slide relative to the outer ring without generating additional axial forces within the shaft system.

Common Model Designations

The designation for an N-type bearing consists of a type code, a dimension series code, and a bore diameter code, following the format: N + Dimension Series + Bore Diameter Code. N: Designates an N-type single-row cylindrical roller bearing.

Bore code: 00=10mm, 01=12mm, 02=15mm, 03=17mm; for codes 04 and above, multiply by 5 to obtain the bore diameter in millimeters.

For example, N310 denotes an N-type, 3-series single-row cylindrical roller bearing with a 50mm bore. Suffixes can further specify parameters such as cage material (M = brass cage, J = pressed steel cage), precision class (P6/P5/P4), and internal clearance (C1 to C5).

Series Applications

Common series include the 2 series (light/narrow), 3 series (medium/narrow), 4 series (heavy/narrow), and 10 series (extra-light/wide).

N2 Series: Moderate loads and relatively high speeds; widely used in electric motors, pumps, and compressors.

N3 Series: Higher load-carrying capacity; suitable for gearboxes, internal combustion engines, and speed reducers.

N4 Series: Heavy loads and medium-to-low speeds; used in mining machinery and metallurgical equipment.

N10 Series: Small outer diameter and large width; suitable for machine tool spindles and precision equipment.

Key Advantages

The advantages of N-type bearings are primarily reflected in four areas:

High radial load capacity: The line-contact structure provides a large load distribution area, making it suitable for heavy loads and shock loads.

High limiting speed: Pure rolling motion between rollers and raceways results in low friction and minimal heat generation, offering high-speed performance comparable to ball bearings.

Separable mounting: The inner ring assembly and outer ring can be mounted separately; this is particularly advantageous for applications requiring an interference fit for the inner ring and a clearance fit for the outer ring, facilitating easy installation and maintenance.

Thermal expansion compensation: Acting as a floating-end bearing, it accommodates the shaft's thermal expansion, preventing the generation of additional axial forces within the shaft system due to temperature rises. 

Limitations

Cannot withstand axial loads; unsuitable for use as the locating end of a shaft system;

Requires high installation coaxiality; excessive misalignment between the inner and outer rings causes stress concentration at the roller edges, shortening service life;

The rib and roller end faces require adequate lubrication; poor lubrication leads to heat generation and wear.

Application Scenarios

N-type bearings are widely used in industrial sectors; typical applications include:

Small and medium-sized electric motors: Positioned at the non-drive end as the floating end, paired with a ball bearing at the drive end to compensate for rotor thermal expansion;

Pumps and compressors: Rotor support for centrifugal pumps, vacuum pumps, and screw compressors, utilizing their high-speed and floating capabilities;

Gearboxes and speed reducers: Floating end for high-speed and intermediate shafts, bearing radial forces generated by gear meshing;

Internal combustion engines: Support for the free end of the crankshaft, bearing radial loads transmitted by the piston connecting rod;

Metallurgical and papermaking equipment: Auxiliary support for long shaft systems such as conveyor rollers and drying cylinders.

In these applications, axial positioning of the shaft system is typically handled by an angular contact ball bearing, Tapered Roller Bearing, or thrust bearing at one end, while the N-type bearing is placed at the other end as the floating bearing; together, they form a complete support solution.

Differences from Other Models

Single-row Cylindrical Roller Bearings come in five basic models—N, NU, NJ, NF, and NUP—based on their rib configurations. While their rolling elements and cage structures are essentially identical, the core differences lie in the position and number of ribs, which determine their respective axial positioning capabilities.

N-type vs. NU-type: Both are floating bearings with identical functionality, capable of bearing only radial loads. The difference lies in which ring features the ribs: the N-type has two ribs on the inner ring and none on the outer ring (allowing the inner ring assembly to be removed as a unit), whereas the NU-type has two ribs on the outer ring and none on the inner ring (allowing the outer ring assembly to be removed as a unit). Selection depends largely on installation and maintenance preferences: the N-type is more convenient if the inner ring needs frequent removal from the shaft while the outer ring remains in the housing bore; conversely, the NU-type is preferred if the reverse is true. Both types are extensively used in the electric motor and internal combustion engine industries. N-type vs. NJ-type: The NJ-type features two ribs on the outer ring and one rib on the inner ring; the single rib on the inner ring allows it to support axial loads in one direction, making it a unidirectional locating bearing. In contrast, the N-type has no axial load-carrying capacity. The NJ-type is suitable for applications requiring some axial location, such as gearboxes and railway axle boxes; it is often used in conjunction with an L-shaped thrust collar (angle ring) to enhance axial locating capability.

N-type vs. NF-type: The NF-type features two ribs on the inner ring and one rib on the outer ring—the reverse of the NJ-type configuration—and is also a unidirectional locating bearing. The single rib on the outer ring supports axial forces. NF-type bearings are less common and are primarily found in specific applications like transmissions.

N-type vs. NUP-type: The NUP-type builds upon the configuration of two outer-ring ribs and one inner-ring rib by adding a detachable flat thrust collar to the side of the inner ring that lacks a rib, thereby achieving bidirectional axial location. The NUP-type can support axial loads in both directions; however, the load-carrying capacity of the flat thrust collar is limited, making it suitable for applications requiring bidirectional location but involving only moderate axial loads. By comparison, the N-type offers no axial locating capability but features a simpler structure and lower cost.

Summary: N-type and NU-type bearings are purely non-locating (floating) bearings; NJ-type and NF-type are unidirectional locating bearings; and NUP-type are bidirectional locating bearings. When selecting a bearing, first determine whether the shaft system requires axial location, then choose the specific model based on installation practices and the direction of the load.

Installation and Maintenance

When installing N-type bearings, the inner ring typically has an interference fit with the shaft; small bearings are pressed on using a press, while medium and large bearings are heated to 80–100°C using an induction heater for hot mounting. The outer ring usually has a transition or clearance fit with the housing bore and can be pressed in directly. Since the bearing is separable, it is recommended to mount the inner ring onto the shaft and the outer ring into the housing bore separately before assembling them together; this prevents the rollers from being subjected to impact forces.

During disassembly, the inner ring is removed using a hydraulic puller or by heating it (removing it while hot), while the outer ring is pressed out of the housing bore. Do not strike the bearing directly with a steel hammer, and do not transmit force through the rolling elements.

Regarding maintenance, grease lubrication is used for low-to-medium speeds, with a fill volume of one-third to one-half of the bearing cavity; oil lubrication is used for high speeds. Monitor temperature (generally not exceeding 80°C), vibration, and noise regularly during operation, and disassemble for inspection promptly if any abnormalities are detected. For high-temperature or heavy-interference fit applications, select bearings with C3 or C4 clearance classes to compensate for the reduction in clearance caused by the fit and temperature rise.

Summary

N Type Cylindrical Roller Bearings is a single-row bearing featuring an inner ring with two ribs and an outer ring without ribs. Classified as a fully floating bearing, it supports only radial loads and is primarily used at the floating end of a shaft system to accommodate thermal expansion. It offers advantages such as high radial load capacity, high limiting speeds, and separable components for easy installation, making it widely used in equipment such as electric motors, pumps, gearboxes, and internal combustion engines. While it shares the same functionality as the NU type, the rib configuration differs; the key distinction from NJ, NF, and NUP types lies in the presence and direction of axial locating capability. When selecting a bearing, first determine whether axial location is required for the shaft system, then choose the appropriate model based on load conditions and installation or maintenance practices.