RNA 49 Series Needle Roller, No Inner Ring Bearings

The same 49 dimension series as the NA, with the inner ring left out: an RNA4900 is 14 mm across the needle complement, 22 mm outside and 13 mm wide, and it runs directly on a hardened and ground 14 mm shaft where its NA4900 partner would have carried a 10 mm bore. Read the code carefully — it is the complete bearing's bore code, not the shaft. RNA 4905 mounts on a 30 mm shaft, not the 25 mm its code would suggest.

Reading the designation — and the one field that is not about this bearing. RNA4900 is RNA, then 4, then 9, then 00. The 4 is the width series and the 9 the diameter series, both ISO 15's digits, so the outside diameters are the 61900 ladder's and every NA49 row beside this one carries the same D. The 00 is a bore code — and here it names nothing this bearing has. RNA4900 runs on a 14 mm shaft; the 00 that means 10 mm on every other page in this library means nothing at all here. The code is kept because the two halves of one ISO 1206 row have to sort together — RNA4905 and NA4905 are the same row of the same table — not because it measures anything on this bearing. RNA4905 reads 05 and runs on a 30 mm shaft, not the 25 mm the code would suggest; RNA 49/32 reads 32 and runs on a 40 mm one. Every page here prints the shaft diameter beside the code for that reason.

Fw is the number that does name it. Fw is the needle complement diameter, and on a complete bearing it is the inner ring's raceway. With the inner ring gone it is the shaft, so Fw is simultaneously the bore this type does not have and the seat it does. An RNA4900 is 14 mm at Fw, 22 mm outside and 13 mm wide. Its NA4900 partner is 10 mm at d, 14 at Fw, 22 outside and 13 wide. Put the two rows together and the arithmetic of the whole type is visible in one line: the outer ring, the rollers and the cage are identical, the inner ring was 2 mm of wall, and that wall is now shaft — the seat grows from 10 to 14 mm, 2 mm on each side, and nothing else moves. The band the rollers work in, between Fw and D, is 4 mm deep in both.

The width is called C here and B there, and it is the same width. ISO 1206 tabulates one figure per row for the width and names it after the part it measures: B on the complete bearing, where the number is the inner ring's width, and C on the bearing without an inner ring, where it is the outer ring's. The figure does not change — 13 mm on both the NA4900 and the RNA4900 — only the symbol does. This library prints the symbol the plan prints, so the same 13 mm appears as B on one page and C on the other. Reading either as the other is harmless in the 49 series, where the two rings are flush; on a tapered roller it would not be, which is why the symbol is carried through rather than normalised.

One row of ISO 1206, read twice — and the build checks that it is. There are 43 designations of each kind here, and the RNA rows are derived from the NA rows rather than transcribed a second time, so the two can only disagree if the derivation itself is wrong. It is checked at build time anyway: an assertion compares Fw, D, the width and the chamfer minimum cell by cell, 43 rows out of 43, and fails if a hand-written RNA table ever replaces the derivation with figures that differ in one cell. So "the same row" is not a claim this page makes — it is a property the build enforces. The ISO 1206 page sets out the two readings side by side.

The seat is a machining instruction, not a bore. Fw is a fit surface, and that is a different kind of requirement from a bore. A shaft that carries an inner ring needs to be round and to hold the ring; a shaft that *is* the raceway needs to be hardened and ground, because the rollers run on it directly and every mark in it is a mark in the raceway. The manufacturer data consulted for this batch give this surface a shaft fit tolerance rather than a bore tolerance — a band, not a nominal size. This library does not print that band: it states boundary dimensions, and the shaft's hardness, roundness and finish are not among them. Take them from the catalogue of the bearing you actually buy, and machine the shaft before you fit it, not after.

Why no clearance table is printed on these pages. The same reason the complete NA bearings give: ISO 5753-1 does tabulate a radial clearance for needle roller bearings, and these sizes fall inside it, so the figure exists — but the catalogue reproductions of that table disagree in every clearance group, so none can be confirmed as the standard's own. Under this library's rule that a published figure needs two independent sources agreeing, the table is left out and the ISO 5753-1 page shows both readings instead.

What is not in this series. Dimension series 59 and 69 are needle roller series too and are not tabulated here yet; drawn cup needle roller bearings belong to ISO 3245, not ISO 1206, and are not here either. The complete bearings these rows belong to are tabulated beside them, as the NA 49 series — the same table with the inner ring in place. Each of these is a deliberate boundary rather than an omission, and the roadmap on the bearings index records them.

Every designation in the table below links to its own page with the ISO 1206 boundary dimensions, the bore-code arithmetic, the needle complement diameter and the shaft the bearing runs on.

This series runs from a 14 mm to a 160 mm shaft. The sub-library as a whole reaches 300 mm of bore, and the widest single bearing in it is a 6360, 620 mm across, in the 6300 series. It shares its outside-diameter ladder with the complete bearings of the same dimension series.

Fw = needle complement diameter, D = outside diameter, C = width. All of them are ISO 1206 standard values and are the same for every manufacturer. r s min is the minimum single chamfer dimension the plan gives; its matching maximum is in ISO 582, which is why the column says “min” and not an equality. The last column is derived: radial section = (D − Fw) / 2, the wall thickness you are working with when you size the housing. No load rating and no limiting speed appears here — see the bearings index for why.

Outside diameter × overall size in millimetres, for the 5 smallest bores in this database. The full charts, one per type, are on the bearings index. Reading a row is what a machine designer does when the shaft is already fixed: the bore does not change, the housing bore does. Across the type boundary the last number changes meaning — it is a width above and a height below — so compare within a type, then decide whether the job wants a ball bearing, a tapered roller or a thrust bearing at all. The 2 series whose type has no bore are not rows here: they are indexed by the shaft they run on, and their chart is above.