What is the difference between cylindrical bearings and needle bearings?

Needle roller bearings are equipped with thin and long rollers (roller diameter D ≤ 5mm, L / D ≥ 2.5, L is the roller length), so the radial structure is compact, the inner diameter size and load capacity are the same as other types of bearings The smallest outer diameter is especially suitable for support results with limited radial mounting dimensions. Depending on the application, bearings or needle roller and cage assemblies without inner ring can be used. The journal surface and the housing hole surface that match the bearing directly serve as the inner and outer rolling surfaces of the bearing to ensure load capacity and running performance. As with ferrule bearings, the hardness of the raceway surface of the shaft or housing bore, the machining accuracy and surface quality should be similar to the raceway of the bearing ring. This type of bearing can only withstand radial loads.

First, from the shape point of view, there are two different criteria for the difference between the needle roller and the roller: the first is the ratio of 2.5 is the boundary point. The second standard is based on a ratio of 4.

Second, from the perspective of force, the needle roller does not bear axial force at all (the end face of the needle roller is not ground, if it is in contact with the shoulder, the friction is very large), and the roller, if the raceway has a shoulder If you can withstand a certain axial force, of course not too big, the principle is not more than 1/10 of the radial force.

Third, from the application point of view, needle roller is mainly used in places where space is limited, so it is widely used in automobiles, motorcycles and textile machines. Moreover, the inner ring of the needle roller is optional. To put it bluntly, if the hardness and roughness of the shaft meet the requirements, the inner ring may not be matched (the space is inherently limited), but if the machining degree of the shaft is relatively low, or relatively soft, An inner ring is also required as a raceway. Rollers are often used to support the floating end of the shaft to absorb the amount of expansion of the shaft. The four rows of rollers on the machine are used more, mainly because the roller has a very large bearing capacity.

The above is a small series for everyone to analyze the general difference between these two types of products, users must be aware of the role and use of their products at the same time!
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