20*37*30 Needle roller bearing NK6904

Needle roller bearing NA6904

Dimension:20*37*30

Once ordered, please inform me which type you need? .... thanks.

Needle bearing is a roller bearing with cylindrical roller, the roller is thin and long relative to its diameter. This type of roller is called a needle roller. Despite the small cross-section, the bearing still has a high load bearing capacity. The needle roller bearing is equipped with thin and long rollers (roller diameter D≤5mm, L / D≥2.5, L is the roller length) The radial structure is compact. When the inner diameter and load capacity are the same as other types of bearings, the outer diameter is the smallest. It is especially suitable for the support structure with limited radial installation size.

According to the different occasions, the bearing or needle roller and cage assembly without inner ring can be selected. At this time, the surface of the journal matching the bearing and the surface of the housing hole are directly used as the inner and outer rolling surfaces of the bearing to ensure the load capacity and running performance. The same as the bearing with ring, the hardness of the surface of the raceway of the shaft or the housing hole, the machining accuracy and the surface quality should be similar to the raceway of the bearing ring. This type of bearing can only bear radial load.

Type

In addition to the bearings listed in the catalog, it can be used for general engineering bearings, such as: open drawn outer ring needle roller bearings (1), closed drawn outer ring needle roller bearings (2), inner ring needle roller bearings (3) and Needle roller bearings with inner ring / Needle roller bearings without inner ring (4), full needle roller bearings with and without cage (5) Our company can also supply various types of needle roller bearings, 1. Needle cage assembly; 2. Needle roller bearings without ribs; 3. Self-aligning; 4. Combined needle roller / ball bearings 5. Combined needle roller / thrust ball bearings 6. Combined needle roller / cylindrical roller thrust bearings.

Compared

1. The friction coefficient of rolling bearings is smaller than that of sliding bearings, and the transmission efficiency is high. The friction coefficient of general sliding bearings is 0.08-0.12, while the friction coefficient of rolling bearings is only 0.001-0.005;

2. Rolling bearings have been standardized, serialized and generalized, suitable for mass production and supply, and are very convenient to use and maintain;

3. Rolling bearings are made of bearing steel and have undergone heat treatment. Therefore, rolling bearings not only have high mechanical properties and long service life, but also save expensive nonferrous metals used in the manufacture of sliding bearings;

4. The internal clearance of the rolling bearing is small, and the machining accuracy of each part is high, therefore, the running accuracy is high. At the same time, the rigidity of the bearing can be increased by preloading. This is very important for precision machinery;

5. Some rolling bearings can bear radial load and axial load at the same time, therefore, the structure of the bearing support can be simplified;

6. Due to the high efficiency of the rolling bearing transmission and less heat generation, the consumption of lubricating oil can be reduced, and lubrication and maintenance are relatively simple

7. Rolling bearings can be easily applied to shafts in any orientation in space.

Precautions

The needle bearing has a large load-bearing capacity and is suitable for supporting structures with limited installation dimensions.

The surface of the journal is hardened as a rolling surface, and the bearing is inserted into the seat hole by press-fitting. There is no need to axially position it. Bearings should be filled with a proper amount of grease before installation. Normally, after assembly, there is no need to relubricate. BK type bearings are used for the support of the journal without the protruding end. The end face is closed to seal and can withstand small axial movement.

The needle roller bearing is equipped with thin and long rollers (the length of the roller is 3 to 10 times the diameter, and the diameter is generally not more than 5mm), so the radial structure is compact, and its inner diameter size and load capacity are the same as other types of bearings. The smallest diameter, especially suitable for the support structure with limited radial installation size. Needle roller bearings should be combined with bearing rings and applications depending on the application occasions, machining accuracy and surface quality. The needle roller bearing is a bearing unit composed of a radial needle roller bearing and a thrust bearing component.