INANA6913Machined Needle Roller Bearing With Inner Ring, 70 x 100 x 30 mm, Open, X-life — 95 kN Dynamic

Product Description

What this part is

A Schaeffler INA machined needle roller bearing, single row, complete with a separable inner ring: 70 mm bore, 100 mm outside diameter, 30 mm wide. Needle rollers are long, slim cylindrical rollers — length several times diameter. Packing many of them into a small annulus gives an enormous number of line contacts, which is why this bearing carries a very high radial load from a radial section of only 15 mm. Where a deep groove ball bearing of the same bore would need a much larger outside diameter, this one fits inside a tight housing.

The inner ring is the reason to buy this variant:
Needle roller bearings come in two forms and the distinction decides whether the part works on a given machine. An NA bearing includes an inner ring. An RNA bearing runs its needles directly on the shaft.

Running needles on a bare shaft demands a shaft raceway hardened to bearing hardness, ground, and held to bearing-quality tolerance and surface finish. That is a real manufacturing operation. On a shaft that is soft, turned rather than ground, or worn, the needles will indent and score it in short order. The NA variant sidesteps the whole problem: the inner ring is a proper hardened, ground raceway that slides onto an ordinary shaft. This is the NA4914-XL, so the inner ring is included.

The inner ring is separable from the cage-and-outer-ring assembly. That is a mounting convenience — the inner ring presses onto the shaft, the outer assembly into the housing, and the two are then brought together — and it also means the two halves can be handled apart. The halves are matched to each other.

Decoding the designation

NA: machined needle roller bearing with inner ring, as against RNA, without.

49: dimension series.

14: bore code, 70 mm.

XL: Schaeffler’s X-life performance class — tighter geometry and surface finish, giving a higher rating and longer achievable life than the preceding build.

Seal suffix: none, so this is the open version. The sealed variant carries a 2RSR or similar suffix.

Published ratings and lubrication

Bore (d): 70 mm.

Outside Diameter (D): 100 mm.

Width (B): 30 mm.

Dynamic Radial Load Rating Cr: 95,000 N (21,400 lbf), per bearing.

Static Radial Load Rating C0r: 156,000 N (35,100 lbf), per bearing.

Fatigue Load Limit Cur: 28,000 N, per bearing.

Limiting Speed: 5,700 rpm.

Reference Speed: 3,250 rpm.

Internal Clearance: Normal. The NA4914-XL-C3 is the looser variant.

Closure Type: Open.

Cage Type: Machined, guided in the outer ring.

Raceway Diameter Inner Ring (F): 80 mm.

Axial Displacement (s): 1.5 mm.

Minimum Chamfer Dimension (r min): 1 mm.

Lubricant: oil or grease, through the groove and oil hole in the outer ring.

Number of Rows: 1.

Operating Temperature: −30 °C to +120 °C.

Item Weight: 0.732 kg (1.61 lb).

Harmonization Code: 8482.40.00.00.

The outer ring’s lubrication groove and oil hole are worth planning for. Needle bearings run a very large number of small contacts in a thin oil film and they are less tolerant of marginal lubrication than a ball bearing — the slim rollers are prone to skewing if starved. The groove and hole let the housing feed oil or grease directly into the roller path.

Why the static rating sits above the dynamic rating:
C0r of 156 kN against Cr of 95 kN is the normal shape of a needle roller bearing, and both figures are Schaeffler’s own. The dynamic rating is a rolling-fatigue figure earned over a defined number of revolutions. The static rating is a permanent-deformation limit on a stationary bearing, where the full needle complement shares the load at once along its whole contact line. A dense set of long line contacts resists indentation far better than it resists fatigue cycling, so the static figure runs well ahead of the dynamic one on this bearing type.

Limiting speed and reference speed

Limiting Speed, 5,700 rpm, is the mechanical ceiling set by cage strength and lubricant retention. Reference Speed, 3,250 rpm, is the thermally-derived figure at which the bearing settles at a defined steady-state temperature rise under reference conditions, and it is the governing number for ordinary continuous duty.

Quantity and configuration

Unit Quantity: 1 Pc. One complete bearing: outer ring, needle roller and cage assembly, and the separable inner ring. The load ratings above are per bearing. Being open rather than sealed, lubrication and contamination exclusion are the housing’s responsibility.

Interchange guidance

Search forms include NA4914-XL, NA4914XL, NA 4914 XL, NA-4914-XL, NA 49/14 XL, NA4914, NA49/14. Related builds: NA4914-XL-C3 (C3 clearance), RNA4914 (same envelope without the inner ring, which calls for a hardened, ground shaft raceway), and NA4914-2RSR where seals are required. Same-envelope equivalents at 70 × 100 × 30 mm are catalogued by SKF, IKO (NA4914), NTN, NSK and Koyo under the same ISO NA49-series numbering. The adjacent NA4910-XL is a different bore, so the family number alone is not enough to order by.