Rotary shaft seal types
SB oil seal: single lip, metal outside diameter
An SB seal is a single spring-loaded lip in a bare metal case, for retaining oil or grease on a clean duty where the bore must locate the seal exactly. 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.
- Family
- Radial lip seals
- Designation
- SB
- Lips
- 1
- Dust lip
- No
- Garter spring
- Yes
- Outside diameter
- Metal
- Case
- single metal case
- Pressure
- 0.3 bar (4.4 psi) (rated by NOK® for its standard types; not a pressure seal)
Radial lip seals
A flexible lip pressed against a rotating shaft by a garter spring, held in the housing by a case. This is what most people mean by an oil seal, and it retains lubricant at low pressure rather than holding pressure.
When to use it
Retaining oil or grease where the outboard side is clean and the seat must be exact. The seal must sit precisely and stay put. A metal outside diameter is harder to dislodge and locates better than a rubber one.
When another type fits better
- SC: Single lip, rubber-covered outside diameter, when the duty generates any pressure, or the housing is light alloy or split.
- TB: Sealing lip and dust lip, metal outside diameter, when there is dust on the outboard side.
Watch for
One maker states plainly that a metal outer periphery cannot be used where pressure is generated, because it bleeds and leaks there.
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 | ISO 6194-1 | JIS B 2402 | JASO | DIN 3760/3761 form |
|---|---|---|---|---|
| SB | Type 1 | TYPE 2 | SM | B (our reading) |
Sources: NOK Oil Seals catalogue 014E, read 2026-09-16; Freudenberg Technical Manual for Simmerring® seals and rotary seals, 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.
NOK is a trademark of NOK Corporation; Simmerring is a trademark of Carl Freudenberg KG. The maker designations on this page are the makers' own. No affiliation or endorsement is implied.
Related pages
Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.
Send the shaft, bore and width, or the old seal's markings
The three dimensions or the code printed on the old seal, the speed, any pressure, the fluid and the quantity. A Conquest representative replies with the quote.
Request a quoteLast updated