The needle bearing is a compact, high rigidity bearing system. These are bearings that have cylindrical rollers with a small diameter in relation to their length and are used as a guide bearing and straight movement.
The ends of the rollers are slightly curved to modify the contact line between the raceways and the rollers. This prevents stress spikes at the roller ends and increases bearing life .
As their cross section is low, needle roller bearings have a high load capacity.
Therefore, they are ideal in applications where radial space is limited.
Main features of the needle bearing
Needle bearings are divided into two types:
- Detachable: whose inner ring can be separated;
- Non-separable: with the inner ring that cannot be separated.
There are two shapes of outer ring: spherical and cylindrical. The outer ball ring easily absorbs shaft centre distortion when the cam follower is installed and helps to lessen a bias load.
SKF Needle Bearing Types
SKF needle bearings are available in different variations. Considering the SKF bearing catalogue, we can highlight:
Needle Roller and Cage Sets
Self-contained and ready-to-assemble bearings. They have high load capacity and high rigidity.
They allow for a compact bearing arrangement where the mounting shaft and housing bore can serve as raceways.
As a result, needle roller and cage assemblies require minimal radial space.
The cage assemblies and SKF needle roller receiving designation identifying the series K, for example K or K 15x19x13 12x15x13 TN.
In addition, they are available in single-row (no designation suffix ) and double-row (ZW designation suffix) models .
Needle bearings with stamped cover
With a thin-walled, drawn-down outer ring, these bearings are often used where the housing bore cannot be used as a raceway for a set of needle rollers and cages.
In this way, the mounting of the bearing in the housing takes place with interference fit.
This is a non-separable type bearing as the stamped cap, cage assembly and needle rollers of these bearings form one unit.
The SKF bearing range of stamped cup needle bearings features:
Needle roller bearings with machined rings
Compact solution with high load capacity and high rigidity in relation to its transversal height. This bearing is manufactured in carbon-chromium steel.
SKF manufactures these bearings with or without outer ring flanges and with or without inner ring.
Needle roller bearings with an inner ring have applications where the shaft cannot be hardened and ground. Especially when the axial displacement of the shaft in relation to the bearing is restricted for bearings with an inner ring.
Needle roller bearings without an inner ring are ideal for bearing arrangements where the shaft can be hardened and ground. Also, without having the inner ring allows for a larger shaft diameter.
The axial displacement of the shaft relative to the bearing is limited only by the width of the raceway on the shaft.
Alignment Needle Roller Bearing
Spherical of up to 3° static misalignment, comprising an outer ring with a spherical (convex) outer surface and two polymer seating rings, each with a spherical (concave) inner surface.
As such, this type of bearing allows the bearing to withstand static misalignment of the shaft in relation to the bearing.
Combined Needle Roller Bearing
It is the combination of a radial needle bearing and a thrust bearing .
As a result, these bearings can accommodate combined radial and axial loads. So they offer a very compact solution and a high load capacity.
Matched needle roller bearings allow locked bearing arrangements when radial space is restricted
Especially in applications where other types of locked bearing arrangements take up too much space or where thrust loads are too heavy, speeds are too high or lubrication is inadequate for simple thrust washer arrangements.
Universal Joint Bearings
Manufactured with machined or cold forged pull-out needle bearings incorporating a closed end.
This bearing is used in a variety of applications, including joints in commercial vehicle driveshafts.
Needle Roller Bearing Components
Supplied as separate components, needle roller bearing inner rings can be matched with needle roller and cage assemblies or stamped cup needle bearings.