LYC’s double-row cylindrical roller bearings are divided into bearings with cylindrical inner bore and tapered inner bore (added K behind bearing type). This type of bearing has these advantages, such as compact structure, good rigidity, heavy load carrying capacity, and little distortion under loads. Consequently, it’s applicable for the machine tool spindle. Tapered inner bore could fine adjust clearance, simplify positioning fixture and be convenient to mount and dismount. Type NN, NNU Bearings of type NN have two integral flanges on the inner ring, a flangeless outer ring and a centre flange in the middle. This type of bearing permits axial displacement in double directions of the housing relative to the shaft. The bearings of type NNU have two integral flanges on the outer ring, a non-contacting inner ring and a centre flange in the middle. This type of bearing permits axial displacement in double directions of the housing relative to the shaft. Therefore, this type of bearing is suitable to be used as non-locating bearings. Type NNF Bearings of type NNF are one kind of double-row cylindrical roller bearings full of rollers, which consist of the outer ring with a center flange, two inner rings with double flanges. Rollers are guided by flanges on inner ring, and two inner rings are fixed up by a fastening ring. This structure can carry not only considerable radial load and axial load, but also tilting moment. Therefore, they are suitable to be used as non-locating bearings. Bearings of type NNF have contact seals at two sides. And they are filled with grease lubricant, whose working temperature would be -50℃~+110℃.However, after considering the seal material, available working temperature shall be -40℃~+80℃. Under appropriate conditions, sealed NNF bearing require little maintenance and can be kept for long periods in water vapor or polluted environment. When at mid or high speed, bearing can get make-up lubricating through lubrication groove and bore.