NA 59 Series Needle Roller Bearings

The 49 dimension series in a wider ring. Diameter series is still 9, so the outside diameter at any bore is unchanged — a NA5903 is 17 mm bore, 22 mm across the needle complement and 30 mm outside, exactly as a NA4903 is — and the whole difference is width: 18 mm against the 49's 13. Width series moves from 4 to 5. The ladder opens at a 10 mm bore, where a NA5900 is 16 mm wide against the NA4900's 13, and runs to NA5928 at 140 mm bore, 190 mm outside and 67 mm wide. It carries the same three bores that break the ×5 code as the 49 series — 22, 28 and 32 mm, written NA59/22, NA59/28 and NA59/32.

Reading the designation. NA5903 is NA, then 5, then 9, then 03. NA is the type — a needle roller bearing with machined rings, complete with its inner ring. The 5 is the width series and the 9 the diameter series, and both are ISO 15's digits rather than this library's, which is why the sentence above can point at the 49 series and mean it. Of those two digits only the width moved: a NA5903 and a NA4903 stand on the same 30 mm outside diameter and differ in standing 18 mm and 13 mm wide. The bore code is the 49 series' code unchanged — 00, 01, 02 and 03 are 10, 12, 15 and 17 mm, and from 04 upwards it multiplies by five — except for the three bores in this series that are not multiples of five at all, which are written NA59/22, NA59/28 and NA59/32 and name the bore directly.

Same envelope, same seat, more axial room. Because d, Fw and D are identical to the 49 series row for row, a NA5903 is a drop-in for a NA4903 as far as the shaft and the housing bore are concerned: the same 17 mm shaft, the same 30 mm housing bore. What it is not is a drop-in axially. The extra width sits on both sides of the rollers, so a housing machined for a 13 mm ring will not close on an 18 mm one without 5 mm more room — and the 5 mm is not a constant down the ladder. Against the 49 series the difference runs from 3 mm at the 10 mm bore to 17 mm at the 140 mm one, so the figure to check is the one on the row you are ordering.

What the extra width buys. A needle complement carries load along the line where its rollers touch the raceway, so a longer roller — which is what a wider ring holds — spreads that load over more contact and raises what the bearing can carry in the same radial section. That is the trade this series makes: the outside diameter does not grow, the shaft does not grow, and only the axial room does. How much load a given bearing carries, and how fast it may turn, are catalogue values for the individual part and not properties the boundary dimension plan fixes, so neither figure appears here.

One chamfer value, and it is the 49 series' value. The pages carry a single r s min, which is what ISO 1206 lays out for this type, and the numeric limits behind it are ISO 582's. Because the envelope is the same as the 49 series', so is the corner: a NA5903 takes the same 0.3 mm minimum as a NA4903, and that holds at every bore the two series share. This library does not leave it to the reader to check — every shared bore code is compared cell by cell at build time, and the chamfer has to come out identical while the width has to come out different.

Why no clearance table is printed on these pages. ISO 5753-1 gives needle roller bearings a radial clearance table of their own, and these bores fall inside it — so unlike the tapered and thrust types, the figure exists. What stops it appearing here is the reproductions: the catalogue versions consulted disagree in every clearance group, so none can be confirmed as the standard's own and this library does not publish a figure it cannot attribute. The ISO 5753-1 page sets out both readings side by side.

What is beside it. The same envelope is tabulated on both sides of this one — narrower as the NA 49 series and wider as the NA 69 series — and without its inner ring as the RNA 59 series, which is this table with the inner ring left out and a hardened, ground shaft taking its place as the raceway. Those three complete series are one ISO 1206 envelope drawn at width series 4, 5 and 6. The 48 series is not a neighbour of them: it is a different envelope on diameter series 8, with the 61800 outside diameters where these three have the 61900's, and its ladder starts at a 110 mm bore. What is not in this series is the drawn cup needle roller bearing, which belongs to ISO 3245 rather than ISO 1206 and is a different plan altogether.

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 same-bore comparison against every other series and type.

This series runs from a 10 mm to a 140 mm bore. 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. This one stops short of it.

d = bore diameter, Fw = needle complement diameter, D = outside diameter, B = 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 − d) / 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 4 series whose type has no bore are not rows here: they are indexed by the shaft they run on, and their chart is above.