NJ213 Single-Row Cylindrical Roller Bearing 65x120x23 mm, One-Direction Axial Location, Separable Inner Ring

What this part is:
A single-row cylindrical roller bearing in the ISO 213 size, 65 mm bore, 120 mm outside diameter, 23 mm width. The rollers run in line contact against the raceways rather than point contact, which is why a cylindrical roller bearing of this envelope carries roughly four times the radial load of a same-size deep-groove ball bearing. The trade is that it will not take meaningful thrust unless the ring ribs are arranged to do so — which is exactly what the NJ configuration addresses.

Decoding the designation:
Rollway EP61213UK104 — the legacy Rollway internal designation. The 61213 size code corresponds to the 65 mm bore in the 1200/213 series; the U denotes the single-rib inner ring style that makes this an NJ-type bearing. Rollway does not publish a public suffix decode table, so we are not going to invent a meaning for the K104 modifier.NJ213 — the ISO/DIN 5412 equivalent designation, and the number most buyers will search. NJ means one rib machined onto the inner ring and two ribs on the outer ring.N, NU, NJ, NUP — the rib arrangement family. NU floats axially in both directions; NJ locates in one direction; NUP locates in both via a loose thrust collar. Substituting across these is a design change, not a like-for-like swap.

What these specs mean in practice:
NJ is the workhorse choice for the drive end of a gearbox shaft. Because the inner ring is separable, you can heat-and-shrink or press the inner ring onto the shaft as its own operation, then bring the outer ring and roller assembly to it — far less risk of brinelling the raceways than driving a one-piece bearing into place. The single inner rib gives you one-directional axial location, which is usually enough when a second bearing at the far end handles the opposite direction.

At 23 mm the 213 size is a narrow-section bearing for its diameter, so it suits positions where axial space is tight but radial load is high.

Published ratings and mounting data:
Bore d: 65 mmOutside diameter D: 120 mmWidth B: 23 mmRows: 1Rib arrangement: one rib inner ring, two ribs outer ring (NJ / one-direction location)Inner ring: separableRoller set: caged, not full complementDynamic radial rating Cr: approximately 108 kN for the NJ213 envelope (industry-published figure for the ISO size, not a Rollway-published number — treat as indicative)Static radial rating C0r: approximately 119 kN, same caveatMass: approximately 1.0–1.2 kg depending on cage and sourceInternal clearance: CN (normal) assumed; no clearance suffix appears on this designationLimiting speed: not published for this designation

Quantity and configuration:
Priced and sold as one bearing. Multiple units in stock, so matched-quantity orders for a gearbox rebuild or a fleet of identical motors can be filled from the same production batch — worth asking about if you need consistency across several positions.

Interchange guidance:
The ISO base number NJ213 is the safe search term across brands: SKF NJ 213 ECJ, FAG NJ213-E-XL-TVP2, NSK NJ213W, NTN NJ213, Timken NJ213E, Koyo NJ213. Confirm cage material and internal clearance before substituting, and confirm you actually want NJ rather than NU — the ribs are the difference between a bearing that locates the shaft and one that does not.

Rollway is now part of the Regal Rexnord portfolio, so buyers chasing current-production equivalents will be pointed at Regal Rexnord or the ISO cross rather than a Rollway catalogue number.

An unverified cross-reference we are flagging rather than hiding:
This part has circulated with the cross-reference 1112178C91. The C91 suffix format is characteristic of Navistar / International Truck part numbering, so an OEM application is plausible, but we could find no published source tying 1112178C91 to this bearing. We list it as a search aid only. Verify against your own parts book before ordering on the strength of that number alone.