The double-row cylindrical roller bearing belongs to the floating bearing, and its separability makes it easy to install and disassemble. Both ferrules can be tight fit. The inclined angle of double-row cylindrical roller bearing is almost not allowed.

Double-row cylindrical roller bearing has two structures: cylindrical inner hole and conical inner hole (bearing post code plus K). This type of bearing has the advantages of compact structure, large rigidity, large bearing capacity, small deformation after loading, and is especially suitable for machine tool spindle support. The conical inner hole can also play the role of slightly adjusting the clearance, and can simplify the structure of the positioning device and facilitate installation and disassembly. Commonly used double-row cylindrical roller bearings have the following forms:

NN, NNU type
The outer ring of NN type bearing has no ribs, and the inner ring has ribs on both sides and middle ribs in the middle. It is allowed to produce axial displacement in two directions between the shaft and the bearing pedestal.

The outer ring of NNU type bearing has a rib on both sides and a middle rib in the middle, while the inner ring has no rib. It is allowed to produce axial displacement in two directions between the shaft and the bearing pedestal. Therefore, this type of structure is suitable for bearing at the moving end. The cages of this type of bearing are mostly made of solid cages.

NNF type
NNF type bearing is a double-row fully loaded cylindrical roller bearing. The bearing consists of one outer ring with middle rib and two inner rings with double rib. The roller is guided by the rib of the inner ring, and the two inner rings are fixed together with fastening rings. This structure can not only bear large radial load and axial load, but also bear overturning moment. Therefore, it is often used as fixed end bearing.

Both sides of NNF type bearing adopt contact seal. The bearing is filled with lubricating grease, and the working temperature of the lubricating grease is - 50 ℃ to+110 ℃. However, due to the limitation of the sealing material, the working temperature of the bearing is limited to - 40 ℃ to+80 ℃. NNF bearing with seal does not need maintenance under good service conditions. If the bearing is in water vapor or polluted environment for a long time, and is in medium and high speed operation, the bearing can be supplemented with lubrication through the lubricating oil groove and lubricating oil hole on the outer ring.