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SKF needle roller bearings solve supports with a high radial load and little available height. They use long, thin rollers, so they take up less radial space than other bearings of similar capacity. The catalog holds series with and without an inner ring, machined and drawn cup. That difference, more than the size, defines what can be fitted in each place.
See all SKF bearings references →SKF guide →Needle roller bearings from all brands →SKF deep groove ball bearings →SKF cylindrical roller bearings →
NK 12/12 and NKI 9/12 show the most important difference in the line. The NK has no inner ring: the needles roll on the shaft. The NKI includes it. The same applies between RNA 49/22 and NA 49/22: the initial R marks the version without inner ring of the same series. In NK and NKI, the two numbers separated by the slash are a diameter and the width.
HK 0408 is a drawn cup needle bearing: the outer ring is thin sheet steel and is pressed into the housing. Its four digits combine diameter and width. The letters after the number change the execution and are copied as they are.
When the bearing has no inner ring, the shaft acts as the raceway. It must be hardened and ground; on an ordinary shaft the needles mark the surface in a short time. If the shaft does not meet that condition or is already worn, the way out is the version with an inner ring or a separate inner ring, which forms its own line in the SKF catalog.
A radial needle roller bearing accepts very little misalignment and carries no axial load. If there is thrust along the shaft at that support, an axial or a combined bearing is needed. Check the housing as well: a drawn cup pressed into an oval bore copies that shape and runs under strain.
Send us the complete designation and the quantity. Without a code, measure the shaft diameter where the needles roll, the housing bore and the width, and tell us whether the removed bearing had an inner ring. State whether the shaft is hardened, whether the motion is continuous rotation or oscillation and whether the point has a seal. A photo of the face and one of the edge tell a drawn cup apart from a machined bearing.
No. NKI includes the inner ring; NK rolls on the shaft. The reference dimensions do not match either.
Only if the shaft is hardened and ground. Otherwise the version with an inner ring applies.
It is not advisable: it deforms when pulled out. Order a new one with the same designation.
Can't find the exact model? Write to us with the part number or model you're looking for: we'll find it and quote it, even if it's not listed in the catalog.
A needle roller bearing uses very thin, long rollers in relation to their diameter —the needles— instead of balls or standard cylindrical rollers. This allows it to support a high radial load with a much smaller available space than any other type of bearing, which is the reason it is chosen.
The SKF NK series needle roller bearing is a compact radial bearing without an inner ring, designed to withstand high radial loads in reduced spaces. It is mounted directly on a hardened and ground shaft, which allows reducing the size of the assembly. It is a common solution in applications where the outer diameter is limited and high load capacity is needed. MR Accesorios Industriales supplies this series in sizes that combine bore diameter and width, such as NK 12/12 or NK 16/20.
The SKF HK series needle roller bearing is a caged needle roller bearing with a machined outer ring and no inner ring. It is used when radial space is limited and high load capacity is needed in a reduced diameter. It is common in transmissions, pumps, power tools and production machinery. MR Accesorios Industriales carries this line as a brand and advises you so that you choose the part number that corresponds to your equipment.
Just the manufacturer part number is enough: we will quote it and provide dimensions and equivalents via WhatsApp or email.
