What is Needle Bearings

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

Types of Needle Bearings

Open type drawn cup needle roller bearing (1), closed type drawn cup needle roller bearing (2), needle roller bearing with inner ring (3) and needle roller bearing without inner ring/needle roller bearing without inner ring and without cage (4), with and without cages filled with needle roller bearings (5)

Precautions for using needle roller bearings

Needle roller bearings have a large load-carrying capacity and are suitable for supporting structures with limited installation dimensions. The journal surface is hardened as a rolling surface, and the bearing is fitted into the seat hole by press-fitting, so there is no need to perform axial positioning on it. Bearings should be injected with proper amount of grease before installation. Usually, no relubrication is required after assembly. BK bearings are used in the support of journals without protruding ends. The end faces are sealed for sealing and can withstand small axial movements.

Advantages of Needle Roller Bearing

Needle roller bearings are equipped with thin and long rollers (the length of the rollers 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 is especially suitable for support structures with limited radial installation dimensions. Needle roller bearings vary according to the application occasion, and the machining accuracy and surface quality should be combined with the bearing ring and application. Needle roller bearings are bearing units composed of radial needle roller bearings and thrust bearing components.

Needle bearing installation

Installing full complement needle roller bearings, usually with auxiliary sleeves of.

At this time, the auxiliary roller or the auxiliary sleeve supports the needle roller so that the needle roller does not fall out, and the journal lifts the needle roller with its own chamfer. As the needle bearing slowly moves inward on the journal, the auxiliary roller Or the auxiliary sleeve will slowly withdraw until it is installed to the working position.The outer diameter of the auxiliary roller and the auxiliary sleeve should be 0.1-0.3mm smaller than the shaft diameter. When installing, first coat the inner surface of the outer ring of the bearing with grease, and place the needle rollers close to the inner surface (there should be a gap when putting in the last needle roller), and then put the auxiliary roller instead of the journal or the inner ring of the bearing Or the auxiliary sleeve is pushed into the hole of the outer ring, and its end face is aligned with the end face of the installation shaft or the end face of the inner ring of the bearing installed on the shaft, and then tapped with a press or a hand hammer to apply pressure.

Needle roller bearings can also be installed in this way, that is, the outer diameter of the auxiliary sleeve is coated with a thin layer of lubricating oil, and inserted into the outer ring of the bearing, so that the auxiliary sleeve and the outer ring of the bearing form an annular hole, and then the needle roller is installed in the annular hole. After the needle roller is installed, use the working shaft to push out the auxiliary sleeve.For needle roller bearings without inner ring or outer ring, when installing, first apply a thin layer of grease to the rolling surface of the shaft or housing hole, and then stick the needle rollers to the grease on the installation part in turn. There should be a gap when pasting the last needle roller, and the size of the gap should be 0.5mm on the circumference of the needle roller bearing. Do not squeeze the last roller into it, or install one less needle, because the bearing will be stuck and unable to rotate when it is squeezed hard; Twisted and snapped. For needle roller bearings that only have a stamped outer ring, because the outer ring wall is very thin, do not use a hammer to install it, but use a press to press it in. Because when the hand hammer hits, the pressure is not uniform, and it is easy to cause local deformation of the outer ring of the needle roller bearing.

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