An Overview of Needle Bearings

When operating equipment or machinery that contains moving components, bearings are useful parts that are used to facilitate smoother rotation and to mitigate friction. To serve a diverse set of assemblies and applications, a number of bearings and bearing types may be implemented in order to achieve a specific need. With a needle bearing type in particular, a variety of machinery ranging from automotive transmissions to aircraft controls may benefit from the friction reduction and long rollers provided by the machine element. As needle bearings are a common bearing type used in many applications and assemblies, understanding their construction, functionality, and uses can be highly beneficial for anyone operating such machinery.

As a type of roller bearing, needle bearings feature rollers that exhibit a high length-to-diameter ratio. While a conventional bearing’s roller may have a length that slightly exceeds its diameter, the length of a needle bearing’s roller can often reach four times the size of its diameter. Additionally, the rollers are constructed to be thin and cylindrical like a needle, hence their naming. Despite this slight difference in construction, needle bearings are still very well capable of reducing the amount of friction located between rotating surfaces. To ensure their optimal functionality and longevity, the bearing assembly is also lubricated with grease. While needle bearings implemented in light-duty assemblies may never need a reapplication of oil lubrication, heavy-duty machinery with high loads and speeds require it.

Depending on the installation and its need, needle bearings may be chosen from one of two types. The first type is the full complement needle bearing, that of which contains a full set of needles and is devoid of a retainer. The other main type of needle bearing is the caged needle, and such roller bearings provide roller guidance and spacing through the use of a cage assembly or retainer. As compared to the full complement type, the cage bearing type can only accommodate lower load capacities. Additionally, the caged needle roller bearing also has a much higher capacity for lubrication, allowing it to better serve certain demanding applications.

Besides the two major types of needle bearings, many variations also exist to assist in the operation of varying vehicles, machinery, and apparatuses. For aircraft and their controls, bearings must be able to withstand intense load capacities during static, rotating, and oscillating movements. As such, single and double roller bearing types with grooves and lubrication holes are most often used. For applications that require bearings that are capable of operating under high speeds, thrust bearings may be implemented. Thrust bearings are a type of caged bearing that feature rollers that are installed in an assembly similar to that of wheel spokes. For more heavy-duty applications, a heavy-duty bearing may be used to serve high load applications with their retainer guided rollers. Extending beyond such examples, caged assemblies, loose-needle bearings, drawn-cup, full complement bearings, and many other types may be used depending on the need.