What are Needle Roller Bearings & what are they used for?
The wide spread use of needle roller bearings can be traced back to the 1950’s and the introduction of a needle roller in the transmission of the VW Beetle. Needle roller bearings are named for their thin cylindrical rolling elements or “needle rollers” (think of a rolling pin for a pie crust). Needle roller bearings are most often specified into a design for their low sectional height and relatively high load capacity. These bearings enable smaller and lighter weight designs where capacity and space preclude spherical or ball bearings, and where speed or friction rules out the use of a bushing. Needle roller bearings are able to handle high loads in relation to their size because they utilize linear contact, which disperses the load over the length of the rollers.
Multiple design configurations of needle roller bearings make this product family adept to handling many applications and each individual design has a unique purpose. Let’s take a look at some of the more popular designs:
Drawn Cup Needle Rollers
|Drawn cup needle roller bearings are complete bearing units consisting of a thin-walled, drawn outer cup and a needle roller, available in full complement or cage assembly. Caged bearings utilize fewer rollers which reduces friction, and can therefore handle higher speeds. Because full complement needle rollers utilize more rollers than caged versions they are ideal for lower speeds and higher loads.
|Similar in design to the drawn cup roller bearing, needle roller clutches transmit torque between the shaft and the housing in one direction and allow free overrun in the opposite direction. The individual spring retention of the needle rollers ensures constant contact between the shaft, the needle rollers and the ramps. Applications are generally described as indexing, backstopping or overrunning.
|When the application requires high static, dynamic or shock loads heavy duty needle rollers are ideal. Machined or Heavy Duty Type needle rollers are bearings with a relatively low sectional height and a solid machined outer ring. The solid outer ring provides high rigidity and allows this bearing to handle larger loads than drawn cup needle bearings.
Needle Thrust Bearings
|When high axial load capacities are needed and envelope space is minimal, needle thrust bearings are an option. These bearings consist of a stamped or machined cage and rollers. The cage retaining the rollers is paired with thrust washers that act as raceways. Thrust bearings can be used without thrust washers when the faces of adjacent machine components can serve as raceways, allowing the machine to be even more compact.
National Precision Bearing stocks a wide variety of domestic and imported needle roller bearings and is authorized to distribute for a number of quality manufacturers including Koyo/Torrington, INA, IKO and RBC. MIL SPEC offerings include: MS24462, MS24463, MS24465, MS21438, MS21439 and more.
Visit our needle bearing website at www.nationalprecision.com/needle-bearings for additional information and to view our in depth part interchange tables.
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