Double row cylindrical roller bearing

Cylindrical roller bearings have line contact between the rollers and raceways. They have a high load capacity and primarily bear radial loads. Friction between the rolling elements and the raceway flanges is low, making them suitable for high-speed rotation. Depending on whether the raceways have flanges, they can be classified as single-row cylindrical roller bearings (NU, NJ, NUP, N, NF, etc.) and double-row cylindrical roller bearings (NNU, NN, etc.). This type of bearing has a separable inner and outer ring.

Cylindrical roller bearings with no flanges on either the inner or outer ring allow axial relative movement between the inner and outer rings, making them usable as free-end bearings. Cylindrical roller bearings with double flanges on one side of the inner and outer rings and a single flange on the other side can withstand a certain degree of axial load in one direction. They generally use stamped steel cages or machined solid copper alloy cages. However, some also use molded polyamide cages.

Features:

1. The rollers and raceways have line contact or modified line contact, resulting in a high radial load capacity, suitable for heavy and impact loads.

2. Low coefficient of friction, suitable for high speeds, with a limiting speed close to that of deep groove ball bearings.

3. N-type and NU-type bearings allow axial movement, accommodating changes in the relative position of the shaft and housing due to thermal expansion or installation errors, and can be used as free-end supports.

4. Requires high precision in shaft or housing machining; the relative misalignment of the outer ring axis after bearing installation must be strictly controlled to prevent stress concentration.

5. The inner or outer ring can be separable for easy installation and disassembly.

Product Features: Cylindrical rollers make line contact with the raceway, resulting in high radial load capacity. Suitable for heavy and impact loads, as well as high-speed rotation.

The raceway and rolling elements of cylindrical roller bearings have a specific geometric shape. Improved design results in higher load-bearing capacity. The novel structural design of the flanges and roller end faces not only enhances the axial load capacity but also improves lubrication conditions in the contact area between the roller end faces and flanges, thus improving bearing performance.

NN and NNU Types

NN type bearings have no flanges on the outer ring, but flanges on both sides and a central flange on the inner ring. This allows for axial displacement in both directions relative to the bearing housing.

NNU type bearings have flanges on both sides and a central flange on the outer ring, but no flanges on the inner ring. This also allows for axial displacement in both directions relative to the bearing housing. Therefore, this type of structure is suitable for use as a floating end bearing. The cage of this type of bearing is usually a machined solid cage.

NF Type
NNF type bearings are double-row full complement cylindrical roller bearings. The bearing consists of an outer ring with a central flange and two inner rings with double flanges. The rollers are guided by the flanges of the inner rings, and the two inner rings are fixed together with retaining rings. This structure can withstand large radial and axial loads, as well as overturning moments; therefore, it is commonly used as a fixed end bearing.

NF type bearings use contact seals on both sides. The bearing is filled with grease, which has an operating temperature range of -50℃ to +110℃. However, due to limitations imposed by the sealing material, the bearing’s operating temperature is limited to between -40℃ and +80℃. Under favorable operating conditions, sealed NNF bearings require no maintenance. If the bearing is exposed to moisture or contaminated environments for extended periods and operates at medium to high speeds, lubrication can be replenished through the lubrication grooves and holes on the outer ring.