Radial shaft seals
Rotary shaft seal cross-reference: letter codes to ISO, DIN, JIS and JASO
The same rotary shaft seal carries a different name in each scheme: TC in the letter codes most seal boxes use, Type 4 with lip in ISO 6194-1, TYPE 4 in JIS B 2402 and D in JASO. The table groups eight constructions by outside diameter and marks where a scheme has no equivalent. Conquest Seal supplies radial shaft seals, also sold as rotary shaft seals, rotary lip seals and oil seals, in inch and metric sizes. Send the part number or drawing and we quote it.
Cross-reference table
A designation match is not a fit, form and function match. These schemes measure different things, and the same letter means different things in different catalogs. Confirm the three dimensions, the lip material and the duty against the drawing before substituting any seal.
| Letter code | Construction | Duty | DIN 3760/3761 form | ISO 6194-1 | JIS B 2402 | JASO |
|---|---|---|---|---|---|---|
| SC | Single lip, rubber-covered outside diameter | Oil or grease where there is no dust | A (our reading) | Type 4 | TYPE 1 | S |
| TC | Sealing lip and dust lip, rubber-covered outside diameter | Oil or grease with dust on the outboard side | AS (our reading) | Type 4 With Lip | TYPE 4 | D |
| VC | Grease or dust seal, rubber-covered outside diameter, no spring | Sealing grease in or dust out. Takes no pressure at all. | none on file (our reading) | no equivalent | no equivalent | G |
| KC | Grease seal for dusty duty, rubber-covered outside diameter | Sealing grease in where there is some dust on the other side. Takes no pressure. | none on file (our reading) | no equivalent | no equivalent | P |
| SB | Single lip, metal outside diameter | Oil or grease where there is no dust, and where the bore needs an exact, secure seat | B (our reading) | Type 1 | TYPE 2 | SM |
| TB | Sealing lip and dust lip, metal outside diameter | Oil or grease with dust on the outboard side, in a bore that needs an exact seat | BS (our reading) | Type 1 With Lip | TYPE 5 | DM |
| VB | Grease or dust seal, metal outside diameter, no spring | Sealing grease in or dust out. Takes no pressure at all. | none on file (our reading) | no equivalent | no equivalent | GM |
| KB | Grease seal for dusty duty, metal outside diameter | Sealing grease in where there is some dust on the other side. Takes no pressure. | none on file (our reading) | no equivalent | no equivalent | PM |
Sources: NOK Oil Seals catalogue 014E, page 8, read 2026-09-25; NOK Oil Seals catalogue 014E, Table 5-3, read 2026-09-16; Freudenberg Technical Manual for Simmerring® seals and rotary seals, Fig. 9, read 2026-09-16; ISO 6194-1: Rotary shaft lip-type seals incorporating elastomeric sealing elements, Part 1: Nominal dimensions and tolerances, ISO 6194-1:2007, read 2026-09-27; JIS B 2402-1: Rotary shaft lip-type seals incorporating elastomeric sealing elements, Part 1: Nominal dimensions and tolerances, Japanese Standards Association, JIS B 2402-1:2013, read 2026-09-27.
How each scheme names a seal
The industry letter codes
The first letter is the lip configuration and the second is the outer periphery. S is a sealing lip on its own, T adds a dust lip, and V and K are grease and dust duty that take no pressure at all. B is a metal outer periphery and C is a rubber-covered one. Widely used across the trade. The first-letter meanings above are our reading of NOK's type descriptions, and the second-letter meanings are NOK's own outer-periphery key.
ISO 6194-1
ISO numbers its types; it does not letter them. The international dimensional standard. Current revision ISO 6194-1:2007.
DIN 3760/3761 forms
DIN letters its forms by outer casing: A is an elastomer casing, B a sheet metal case, C a sheet metal case with a fixed metal cap. The trailing S on AS, BS and CS is the dust lip. The maker manual on file puts form A under DIN 3760 and forms B and C under DIN 3761, but names DIN and ISO for all of them in its figure, so both numbers are given here. The form letters are the vocabulary most European catalogs use.
JIS B 2402
Numbered, like ISO, but the numbers are not the same numbers. The Japanese industrial standard.
JASO
A trailing M marks the metal-outer variant of the same seal. The Japanese automotive standard.
Sources: NOK Oil Seals catalogue 014E, page 8, read 2026-09-25; NOK Oil Seals catalogue 014E, Table 5-3, read 2026-09-16; Freudenberg Technical Manual for Simmerring seals and rotary seals, Fig. 9, read 2026-09-16; ISO 6194-1: Rotary shaft lip-type seals incorporating elastomeric sealing elements, Part 1: Nominal dimensions and tolerances, ISO 6194-1:2007, read 2026-09-27; JIS B 2402-1: Rotary shaft lip-type seals incorporating elastomeric sealing elements, Part 1: Nominal dimensions and tolerances, Japanese Standards Association, JIS B 2402-1:2013, read 2026-09-27.
Three traps between the schemes
- ISO numbers its types; DIN letters its forms. An ISO type number and a DIN form letter are not the same designation and cannot be read across. One maker's own manual runs the two together in a figure caption, which is how the confusion spreads.
- The letter A means something different in the SKF® scheme. In the industry codes the second letter is the outer periphery. In SKF's designations A means a contacting auxiliary lip and B means a non-contacting one, which is close to the opposite sense. An H inside a code such as CRWH1 means a double metal case.
- Grease and dust seals have no ISO or JIS equivalent at all. The V and K types map to a JASO designation and to nothing in ISO or JIS. Any table that shows an ISO number for them has invented it.
Sources: NOK Oil Seals catalogue 014E, page 8, read 2026-09-25; Freudenberg Technical Manual for Simmerring seals and rotary seals, Fig. 9, read 2026-09-16; SKF Industrial Seals, Product Overview, read 2026-09-16.
Maker designations beyond the letter codes
Makers also name their own designs, and those names do not cross-reference by letter. NOK adds a suffix for a variant, as in TCV, TCN and TCZ for its pressure-resistant lips. Freudenberg names its pressure designs, such as PTS, BAHD and HLPS. SKF names families, such as HDS and HDL for large diameters, and in its scheme an H inside a code such as CRWH1 means a double metal case.
Send the designation exactly as the seal or the parts list prints it, with the shaft, bore and width, and the cross-reference is checked against the drawing rather than read from a table.
Sources: NOK Oil Seals catalogue 014E, read 2026-09-25; Freudenberg Technical Manual for Simmerring seals and rotary seals, read 2026-09-16; SKF Industrial Seals, Product Overview, read 2026-09-16.
Codes left out, and why
- DC and DB. Neither string appears anywhere in the 139-page NOK catalog on file. They are widely attributed online to a double-lipped seal with a spring on both lips, with no maker document behind the claim. They are left out rather than repeated.
- SA, TA, VA and KA. Real designations that form their own outer-periphery group, but the catalog defines only the metal and rubber-covered groups. What construction the third group uses is not stated in any document on file, so no row is written for it.
NOK is a trademark of NOK Corporation; SKF is a trademark of Aktiebolaget SKF; Simmerring is a trademark of Carl Freudenberg KG. The maker designations on this page are the makers' own. No affiliation or endorsement is implied.
Frequently asked
Is a TC oil seal the same as a DIN form AS seal?
By our reading, yes in construction: both are a spring-loaded sealing lip plus a dust lip in a rubber-covered case. The ISO, JIS and JASO equivalents are the designations the NOK catalog gives each construction; the DIN match is our reading of the form definitions. A match in construction is not a match in size or material, so confirm the three dimensions and the lip compound before substituting.
What is the ISO equivalent of a VC or KC seal?
There is none. The grease and dust types, VC, VB, KC and KB, map to a JASO designation and to nothing in ISO 6194-1 or JIS B 2402. A table that shows an ISO type for them has invented it.
Why does an SKF code not match the letter codes?
SKF uses its own designation letters. In its scheme A marks a contacting auxiliary lip and B a non-contacting one, which is close to the opposite of the industry letters, where the second letter describes the outside diameter. Read an SKF code against SKF's own key, or send it as printed with the dimensions.
Related pages
Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.
Send the code as it is printed, with the three dimensions
The designation on the seal or the parts list, the shaft, bore and width, the lip material if known, and the quantity. A Conquest representative replies with the quote.
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