Bearings

What the designation says. The number is usually three fields, not one, and in the cylindrical roller series it is four. It opens with the type code — 6 for a single-row deep groove ball bearing, 3 for a single-row tapered roller bearing, 5 for a single-row thrust ball bearing, 1 for a self-aligning ball bearing, N for a single-row cylindrical roller bearing, 2 for a double-row spherical roller bearing, NA for a needle roller bearing with machined rings and RNA for the same bearing with the inner ring left out — and closes with the two-digit bore code, which reads the same way in every type here except in three cases: where the code cannot express the bore at all, where the bearing has no bore to name and the code names the complete bearing's instead, and where the closing digits are not a code at all. The exception at the front is the self-aligning 2200 and 2300 families, which put a width series where the other families put a type code: all four self-aligning families are type 1, and only the 1200 and 1300 print that digit. That leading 2 is the one digit in this library worth reading twice, because the spherical roller 22 and 23 series open with it too and there it means the opposite. A 2204 is four digits on the width-series reading — 2 is the width series and the type code 1 is left unwritten; a 22208 is five, and its 2 is the type code itself. The two are told apart by their length, four digits against five, and not by the prefix they share. The cylindrical roller designations add a structure letter between the type code and the series — NU204 is N, U, 2, 04 — and that letter records how the ribs on the two rings are arranged. For 00, 01, 02 and 03 the bore is 10, 12, 15 and 17 mm — special cases. From 04 upwards the code multiplies by five, so 04 is a 20 mm bore and 20 is a 100 mm bore. The needle roller series has three bores the multiplier cannot reach, because 22, 28 and 32 are not multiples of five: there the code names the bore outright and is written after a slash, so NA49/22 is a 22 mm bore needle roller bearing. Needle roller bearings also come without their inner ring, and those designations begin RNA. The row of the boundary table is the same row and the code is the same code — an RNA4905 sits beside an NA4905 — but the bearing no longer has a bore at all: it runs on the shaft, at a diameter the code does not name. RNA4905 reads 05 and takes a 30 mm shaft where the NA4905 takes a 25 mm one, and RNA 49/32 reads 32 and takes a 40 mm one. What sits between type and bore code is the series, and it is the field whose length and meaning vary most. In 6204 it is one digit and names a diameter series; in 61800 it is two digits and names an ultra-thin diameter series; in 30204, 51104 and NU2204 it is two digits and names a dimension series in a plan of its own. Read that way, 6204 unpacks to type 6, series 2, bore code 04 — a 20 mm bore light series bearing; 30204 unpacks to type 3, series 02, bore code 04; 51104 unpacks to type 5, series 11, bore code 04; NU2204 unpacks to type N, structure letter U, dimension series 22, bore code 04; and 22208 unpacks to type 2, dimension series 22, bore code 08. The needle roller plan adds a fourth worked example, because its dimension series is two digits on a two-letter type code: NA4900 unpacks to type code NA, dimension series 49 and bore code 00. They share a bore and almost nothing else. One deep groove series breaks the pattern entirely: the 16000 series is written 160 followed by the bore code, so a 16004 is not type 6 / series 16 / bore 04 — it is a 04 bore in the narrow-width version of the 6000 family. One type leaves the plan altogether: a drawn cup needle roller bearing has no bore code to read and no dimension series to find, because its designation is two boundary dimensions and nothing else. HK1210 is HK, then 12, then 10 — Fw, the diameter the shaft has to be ground to, and C, the width of the cup, both already in millimetres. The outside diameter is in neither of them: HK1210 is 16 mm across where HK1212 is 18, on the same Fw and the same leading digits. That one figure is read from the ISO 3245 table for the diameter series, and it is the only boundary dimension in this library that the designation does not pin down.

The bore code is why one number can replace a drawing. Because the code and the bore are locked together by rule, a buyer who says "6205" has already specified the shaft seat. The catch runs the other way too: two bearings with the same bore are not interchangeable unless the outside diameter and the section dimensions match as well. Within the deep groove family, 61705, 61805, 61905, 6005, 16005, 6205, 6305 and 6405 all take a 25 mm shaft, and seven of the eight need a different housing: 32, 37, 42, 47, 47, 52, 62 and 80 mm. The 6005 and the 16005 are the exception — the same 47 mm housing bore, 8 mm apart in width. Put the other types beside them and the point sharpens further: a 30205 also takes a 25 mm shaft but is 52 mm across with a 16.25 mm total width, a 51105 sits on the same shaft at 42 mm across and 11 mm high, and a NU2205 takes that shaft at 52 mm across and 18 mm wide — the same 52 × 18 as the self-aligning 2205 beside it, with rollers where the 2205 has balls. A needle roller NA4905 takes that shaft too, at 42 mm across and 17 mm wide, and it states a fourth number none of the others need: 30 mm, the diameter of its needle complement — the surface the needles run on. The version of the same row without an inner ring runs on that 30 mm directly: there it is not a bore but the seat itself, and the designation that says so is RNA4905. A 22205 then puts a third reading on that same 52 × 18 envelope: two rows of barrel rollers where the 2205 has balls and the NU2205 has one row of rollers. Three bearings of three different types share that one envelope, and the only thing that separates them is the type code inside the designation. That is the whole reason the series field exists — the shaft is fixed by the machine, the bearing is chosen from the space left around it.

Each type brings its own dimension plan. A deep groove ball bearing is specified by bore, outside diameter and one width, because the rings are flush and there is nothing else to state: that is ISO 15. A tapered roller bearing cannot be specified that way — its inner ring and its outer ring are separate parts of different widths, so ISO 355 gives three numbers where ISO 15 gives one: T, the total assembled width, and B and C, the widths of the inner and outer ring. A 30204 is therefore 20 × 47 × 15.25 mm overall, but its inner ring is 14 mm wide and its outer ring 12 mm — three dimensions that a single "width" column would have quietly collapsed into one. A thrust ball bearing is different again: it is an axial bearing, its washers are flat, and ISO 104 specifies it by bore, outside diameter and an overall height H. A self-aligning ball bearing comes back to ISO 15, and is specified by bore, outside diameter and a single width exactly as the deep groove type is: the two differ in the races — two rows of balls on a sphered outer raceway — not in how their boundary dimensions are stated. A cylindrical roller bearing is also ISO 15, and is also stated as bore, outside diameter and one width — which is why a NU204 is 20 × 47 × 14 mm, the same three numbers a 6204 and a 1204 carry, with a roller complement where those two have balls. A spherical roller bearing comes back to ISO 15 as well and is stated the same way — a 22205 is 25 × 52 × 18 mm, the three figures a 2205 and a NU2205 already carry — and it is the one roller type here whose pages also carry a chamfer column. The reason is what the plan says about the corner: ISO 15 gives this type a single r s min, while for a cylindrical roller it gives a separate minimum for each ring. Where the plan gives a pair, or where the sources checked do not agree on the pair, the column is left off rather than half-filled, and each type's pages state which case they are in. So the size charts below are one per type rather than one wide table, because a column headed "width" would be printing a width in one row and a height in the next.

Boundary dimensions are standard. Ratings are not. The dimensions on these pages come from the boundary dimension plan of each type — ISO 15, ISO 355, ISO 104, ISO 1206 or ISO 3245 — and that is why every maker's 6204 is the same size. Load ratings and limiting speeds are a different kind of number: ISO 281 defines how a dynamic rating is *calculated*, not what it equals, and the answer depends on internal geometry — ball or roller diameter, the complement, raceway conformity — which no boundary dimension plan fixes. Published catalogue values for one and the same designation differ between makes by several percent at the sizes in this batch. So no load rating and no limiting speed appears on any page here. See "What is deliberately not published" below.

A suffix is not part of the size. 6204-2RS and 6204-ZZ have exactly the same bore, outside diameter and width as a plain 6204; the suffix changes the sealing, the clearance group or the tolerance class, none of which the boundary dimension plan has anything to say about. Order by the base designation for size, then add the suffix for the environment.

What is published here, and what is not. 764 designations across 33 dimension series and nine bearing types. Deep groove ball: the 61700, 61800, 61900, 6000, 16000, 6200, 6300 and 6400 series, all to ISO 15, with the ISO 5753-1 radial internal clearance groups. Tapered roller: the 30200 and 30300 series to ISO 355, with the T / B / C breakdown. Thrust ball: the 51100 and 51200 series to ISO 104. Self-aligning ball: the 1200, 1300, 2200 and 2300 series, back to ISO 15, with the radial internal clearance ranges the same standard tabulates for that type — the 1200 and 1300 carry the same envelopes as the 6200 and 6300, one row for one row, and the 2200 and 2300 take those two envelopes and widen them. Cylindrical roller: the NU2, NU3, NU22 and NU23 series, also ISO 15, also with their own clearance ranges — and with the same trick of sharing envelopes, since the NU2 carries the 6200's diameters and the NU22 widens them, exactly as the 1200 and 2200 do. Spherical roller: the 213, 222 and 223 series, ISO 15 once more, and a fourth clearance table — the standard lays out six and this library now reproduces four of them; of the two it omits, one is a type tabulated here without a clearance table and the other is a type with no designations here at all. The three are not a ladder of sizes: 213 and 223 are both diameter series 3 and differ only in width series, so a 21308 and a 22308 are both 90 mm across on a 40 mm shaft, 23 mm wide against 33, while the 222 is the other pairing — width series 2 on diameter series 2 — and a 22205 stands 52 mm across where the 21305 on the same 25 mm shaft stands 62. Needle roller: the NA49, NA59, NA69 and NA48 series to ISO 1206, and the first type here whose table carries a dimension no other plan has — Fw, the diameter of the needle complement, because a bearing without an inner ring races on that surface instead of on a ring of its own. Three of those series are one envelope in three widths rather than three rungs of a ladder: 49, 59 and 69 are width series 4, 5 and 6 all standing on diameter series 9, so a NA4903, a NA5903 and a NA6903 are each 17 mm bore and 30 mm outside and differ only in standing 13, 18 and 23 mm wide. Between them the four series divide the deep groove ladders rather than stepping up a ladder of their own: the 49, 59 and 69 share the 61900 outside diameters and the 48 the 61800. That plan also gives this library two of the types whose pages carry no clearance row at all, for the reason the ISO 1206 page sets out. Needle roller without an inner ring: the same four dimension series with the inner ring left out, as the RNA49, RNA59, RNA69 and RNA48, tabulated row for row against the NA they share a boundary table with — 94 designations each way, and the build compares them cell by cell rather than trusting a second reading of the same table. Three things change and one does not: the first column is Fw rather than d, because the shaft is the raceway and there is no bore to state; the width is called C where the complete bearing calls it B, because ISO 1206 names one figure after the part it measures; the run is on a hardened and ground shaft held to a fit rather than on a ring. What does not change is the code — it stays the complete bearing's, so an RNA4905 runs on a 30 mm shaft and an RNA 49/32 on a 40 mm one. Drawn cup needle roller bearings: the HK and BK series to ISO 3245, one boundary table serving both an open-ended and a single-closed-end cup, so a size that is made in both forms carries two designations and has two pages. The designation states Fw and C and leaves the outside diameter to that table, and the two diameter series it tabulates can both be reached from the same Fw — HK1210 is 16 mm across and HK1212 18 mm. That plan accounts for this library's third type with no clearance row, and for a reason neither of the other two shares: ISO 5753-1 leaves drawn cup needle roller bearings out of its scope in as many words, so there is no table in that standard for this library to print.

What is still absent is listed in the roadmap below: bores beyond 300 mm and the series that stop short of them, toroidal roller bearings, bores below 10 mm and the sealed and shielded variants as records of their own.

Boundary dimensions, tolerances and internal clearance are not industry habit — each is fixed by a numbered standard, and every column on the pages below traces back to one of these. All 7 bearing standards.

Eight of the nine types here close with a two-digit bore code, which is why a 6204, a 30204, a 51104 and a 1204 all take the same 20 mm shaft. The drawn cup needle roller type is the exception, and it is set out at the end of this note. The digits in front of the bore code are not one field with one meaning: 6204, 30204 and 51104 open with a type code — 6, 3 and 5 — and so do the 1200 and 1300 self-aligning families, whose 1 is the self-aligning type code; the 2200 and 2300 put a width series there instead and leave the type code unwritten. What sits between the two is a dimension series whose meaning depends on the type: 6204 is a light diameter series inside one width plan, 30204 is the light series of the tapered roller plan, 51104 is the light thrust series, and 1204 is the light self-aligning series, which shares the 6200’s envelopes row for row. Where two types share a plan they share its dimension set as well, which is why the size charts below are one per type rather than one wide table. One type adds a field rather than replacing one: the cylindrical roller designations here carry a structure letter between the type code and the dimension series, so a NU204 is that type code, then U, then the dimension series, then the bore code. The letter says which ring carries the ribs; the boundary dimensions are the same across NU, NJ, NUP, N and NF, which is why one table covers all five. The code is not always the seat either: in the needle roller, no inner ring designations it names the complete bearing’s bore rather than this one’s fitting surface — an RNA4905 reads 05 and runs on a 30 mm shaft. That is set out in full under “How to read a designation” below. The other exception is the drawn cup needle roller: it carries no bore code at all, and the two pairs of digits that close its designation are boundary dimensions that are already in millimetres. Both cases are set out under “How to read a designation” below.

This table is the rule for the eight types whose designation closes with a bore code. Codes 00 to 03 are the four exceptions to the rule; every code from 04 up is simply multiplied by five. That is why 6204 is a 20 mm bore and 6205 a 25 mm — and why the bore can be read straight off the number without a table.

In the needle roller, no inner ring type the bore code is not this bearing’s own: it is the code of the complete bearing of the same size, so it tells you which bearing this one is the inner-ring-less half of rather than what it mounts on. An RNA4905 reads 05 and runs on a 30 mm shaft, not a 25 mm one; an RNA 49/32 reads 32 and runs on a 40 mm one. Those pages print the shaft diameter beside the code so the two numbers are never read as one.

The drawn cup needle roller type has no code to point anywhere else: its designation ends in two boundary dimensions that are already in millimetres — the shaft it runs on, then its width. The outside diameter is in neither of them, so the same four digits can belong to two bearings of different outside diameters; a drawn cup outside diameter is read from the ISO 3245 boundary table for its diameter series, never from the part number. Each of its designation pages works the reading out in full.

Each cell is outside diameter × width in millimetres, and links to the full page for that designation. Reading down a column walks one series through its bore range; reading across a row is the choice that has to be made once the shaft diameter is fixed — same bore, larger housing, more load capacity. Two columns break that pattern, and both are deliberate: the 16000 column holds the 6000’s outside diameter with a narrower ring rather than a smaller one, and the 6400 column starts at a 17 mm bore because the heavy series has no smaller sizes. All values are ISO 15 boundary dimensions.

Each cell is outside diameter × width in millimetres, and links to the full page for that designation. This type is dimensioned to the same plan as the deep groove bearings above, one row for one row: the 1200 and 1300 series carry exactly the outside diameters and widths of the 6200 and 6300 series, and the 2200 and 2300 series take those same two envelopes and widen them — a 2204 shares the 1204’s bore and outside diameter, and only the width differs. That extra width is what pays for the second row of balls. All values are ISO 15 boundary dimensions.

Each cell is outside diameter × total width (T) in millimetres. The number is deliberately T and not one of the two ring widths: for a tapered roller the standard gives three — T for the assembled bearing, B for the inner ring and C for the outer ring — and B + C is larger than T, because the two rings interpenetrate along the axis. A single “width” column would be answering a question this bearing does not have. Rows start at a 15 mm bore: the 02 and 03 tables of ISO 355 begin at bore code 04. All values are ISO 355 boundary dimensions.

Each cell is outside diameter × overall height (H) in millimetres — the height of the assembled stack, not the thickness of one washer. A thrust ball bearing is three separate parts (shaft washer, ball and cage set, housing washer) and ISO 104 gives only the assembled envelope, so no single washer thickness can be read off this chart. Both series cover the same 21 bore codes less one: the 51200 has no 19 bore, because the only table that lists a 51219 gives a height that breaks its own series ladder and no second source confirms it.

Each cell is outside diameter × width in millimetres, and links to the full page for that designation. Reading down a column walks one series through its bore range; reading across a row is the choice that has to be made once the shaft diameter is fixed — same bore, larger housing, more load capacity. This type is dimensioned on the same ISO 15 plan as the deep groove bearings above, so its series sit on the same outside-diameter ladder: at a given bore the choice is a wider ring or a smaller housing, never a different bore. All values are ISO 15 boundary dimensions.

Each cell is outside diameter × width in millimetres, and links to the full page for that designation. Two rows of barrel rollers on a sphered outer raceway is what the type is: the outer ring can tilt relative to the inner without disturbing the rollers, which is why a spherical roller keeps working through the shaft deflection that would shorten the life of a deep groove bearing. The three series do not invent a ladder to do it — the 222 sits on the 2200’s envelopes, so a 22205 and a 2205 are both 25 × 52 × 18 mm, and the 213 and the 223 sit on the 6300’s outside diameters, so a 21305 and a 6305 are both 25 × 62 × 17 mm while a 22308 keeps the 21308’s 90 mm across in a ring 10 mm wider. This is also the one roller type here whose tables carry a chamfer column: ISO 15 gives it a single r s min, where a cylindrical roller gets a separate minimum for each ring. All values are ISO 15 boundary dimensions.

Each cell is outside diameter × width in millimetres, and links to the full page for that designation. This type carries one column the others do not: Fw, the diameter of the needle complement — the surface the shaft itself runs on when the bearing has no inner ring — so a designation reads d / Fw / D / B and a NA4900 is 10 × 14 × 22 × 13 mm. Fw is not a third axis of the chart: at a fixed bore it is the same for every designation of a series, so the choice across a row is still outside diameter. The 49, 59 and 69 series all ride the 61900 outside-diameter ladder — ISO 1206sends their dimension series back to ISO 15 — so at a given bore they are one envelope in three widths: a NA4903, a NA5903 and a NA6903 are each 30 mm across and stand 13, 18 and 23 mm wide. The 48 series rides the 61800 ladder. Three bores are not a multiple of five and are written with a slash instead: NA49/22, NA49/28 and NA49/32, and the same three appear as NA59/22, NA59/28, NA59/32, NA69/22, NA69/28 and NA69/32 — the number after the slash is the bore in millimetres. All values are ISO 1206 boundary dimensions.

Each cell is outside diameter × width in millimetres, and links to the full page for that designation. This is the one type here with no bore at all: the inner ring is left out and the shaft itself is the raceway, so the first column is Fw — the needle complement diameter, which is also the shaft the bearing is made for. The row is the same row as the complete bearing of the same size: an RNA4900 is 14 × 22 × 13 mm where the NA4900 is 10 × 14 × 22 × 13, so the outside diameter, the width and the needle complement are identical and the only thing gone is the inner ring and the bore it would have had. Two things do not carry over. The width symbol is C here and B on the complete bearing — one figure per row in ISO 1206, named after the part it measures. And the designation closes with the complete bearing’s bore code, not the shaft: an RNA4905 reads 05 and runs on a 30 mm shaft, and an RNA 49/32 reads 32 and runs on a 40 mm one. Fw is a fit surface rather than a bore, so the shaft it runs on must be hardened, ground and held to the fit the type’s pages state. All values are ISO 1206 boundary dimensions.

Each cell is outside diameter × cup width in millimetres, and links to the full page for that designation. This is the one chart here indexed by the shaft rather than by a bore: Fw is the needle complement diameter — the surface the shaft itself is ground to — and the type has no inner ring to put a bore in. A cell can hold more than one designation, and they are all listed: at a fixed Fw the choice within a series is normally the cup width, but the outside diameter is not fixed by the number at all. HK1210 and HK1212 are both 12 mm at Fw, and the first is 16 mm across where the second is 18. Reading down a column walks one series through its shaft range; reading across a row is the choice between the two ends, open or closed, at the same size. All values are ISO 3245 boundary dimensions.

Outside diameter × overall size in millimetres, for the 5 smallest bores in this database, across the 27 series that have a bore. The other 6 series are not in it: they have no bore to be indexed by, because a bearing without an inner ring races directly on the shaft, so the chart above lays that type out by shaft diameter instead. The columns are comparable only one table at a time: the last number in a cell is a width for the seven types here that state a single width, a total width for the tapered roller series, but a height for the thrust series, so a 51104 at 35 × 9 is not “narrower” than a 6204 at 47 × 14 — it is a different kind of part. The full charts, one per type, are above.

Each standard has its own page here, covering what it fixes, what it leaves to another standard, and — where this library has numbers it can check — the values themselves. They sit in the bearings subtree rather than in the main standards index, because a bearing standard is a different shape of document from a fastener product standard: one is a boundary dimension plan, one a formula, one a set of tolerance symbols.

None of these suffixes changes any boundary dimension. A 6204-2RS and a 6204 have identical dimensions; the suffix changes the environment the bearing will survive in, not the shaft or the housing it fits. Note also that the clearance codes sit in the same place as the sealing codes and mean something entirely different — C3 is not a seal, and it applies only to the deep groove ball, self-aligning ball, cylindrical roller and spherical roller series, whose clearance ranges are on each designation’s page.

No load rating, no limiting speed and no mass appears on this page. Those are catalogue values rather than standard values: ISO 281 defines how a dynamic rating is calculated, not what it comes out as, and the result depends on internal geometry — ball or roller diameter, the complement, raceway conformity — that none of the boundary dimension plans (ISO 15, ISO 355, ISO 104, ISO 1206, ISO 3245) fixes. Published catalogue figures for one and the same designation differ between makes by several percent at these sizes, and limiting speed additionally depends on lubrication and on whether the bearing is open, shielded or sealed. Publishing any single figure here would dress a catalogue entry up as a property of the designation. Take the rating from the catalogue of the bearing you actually buy.

The dimensions above are a different matter, and they are the reason a designation is worth anything: the boundary dimensions — bore, outside diameter and the section dimensions of the plan this type is tabulated in, plus the chamfer minimum where that plan gives one — are fixed by the standard, so every maker's bearing of this designation fits the same shaft and the same housing.

The bore ladder does not stop in the same place for every series. Four of the 33 series run to a 300 mm bore — 6000, 6200, 6300 and NA 48; the other 23 stop at 140 mm. So the 300 mm end of the range is a choice of four series rather than of every series in the sub-library.

One series of the ISO 15 plan is not tabulated here: diameter series 1. The rest of the ladder is on the ISO 15 page, with the reason it is a gap rather than a blank.