Products
Radial shaft seals, rotary lip seals and oil seals
A radial shaft seal, also called a rotary shaft seal, rotary lip seal, oil seal or radial shaft sealing ring, is a flexible lip held in a metal or rubber-covered case that presses on a turning shaft to keep lubricant in and dirt, dust and water out. Conquest Seal is a radial shaft seal supplier: single lip, double lip and spring-loaded seals in inch and metric sizes, bought from the manufacturer or its distribution network, with a certificate of conformance with every order. Send the shaft diameter, bore diameter and width, or the equipment part number, and a Conquest representative quotes it.
- Types
- single lip, double lip, spring-loaded, unitized
- Lip materials
- NBR, HNBR, FKM, silicone, PTFE
- Lip service range
- set per seal on its maker's data sheet, not by the compound family
- Sizing
- shaft diameter, bore diameter and width, inch and metric
- To quote
- send the three dimensions, the shaft speed and the equipment part number
What a rotary shaft seal does
A rotary shaft seal sits in the housing bore where a shaft leaves a gearbox, pump or motor. Its lip presses inward on the shaft diameter, which is why it is called a radial seal, and a garter spring behind the lip keeps that contact as the lip wears. The case holds the seal in the bore, either bare metal or covered in rubber. A standard rotary lip seal retains oil or grease at low pressure; it is not a pressure seal unless the maker rates it as one.
Radial shaft seal supplier: sizes, lips and paperwork
Conquest Seal supplies radial shaft seals in inch and metric sizes for pumps, gearboxes, motors and other rotating equipment in industrial, automotive and hydraulic service. We buy them from the manufacturer or its distribution network, and every seal is checked against your drawing or the equipment part number before it ships.
The options are the lip arrangement, the case and the lip material. Single lip, double lip and spring-loaded seals come with a rubber-covered or a metal outside diameter. NBR lips cover general service, HNBR takes more heat than NBR, FKM handles heat and chemical exposure, silicone takes wide temperature swings and PTFE runs dry.
Every order ships with a certificate of conformance naming the part number, the manufacturer, the lot and the quantity. Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.
Lip material, limits and sizes
A radial shaft seal is a lip, a case and usually a garter spring, and the lip compound decides what the seal survives. The temperature limit is set per seal, not by the compound family: the seal maker's data sheet gives it, and the quote names a seal its maker rates for the temperature at the lip.
Speed and pressure limits are set per seal by the maker. A standard lip seal is built to retain lubricant at low pressure, and pressure-rated designs exist for pump shafts, so send the shaft speed and any pressure with the dimensions, and the quote names a seal its maker rates for them.
Three dimensions identify a size, shaft diameter, bore diameter and width, in inch or metric, and the equipment part number often does the same job. Single lip seals retain lubricant, double lip seals add a dust lip on the outside, spring-loaded lips hold contact as the lip wears, and unitized seals carry their own wear sleeve for worn or unhardened shafts.
Send the shaft diameter, bore diameter and width, the lip material if the print names one, and the shaft speed, and we quote from the manufacturers we source from.
High-pressure radial shaft seals: what changes
A standard radial shaft seal is not a pressure seal. NOK® rates its standard oil seal types to 0.3 bar (4.4 psi), enough for a vented or lightly pressurized housing, and says its grease and dust seal types cannot be used under pressure at all; Freudenberg's manual gives 0.2 to 0.5 bar (2.9 to 7.3 psi) for its standard lips. Above that, the lip is pressed onto the shaft harder than it is built for, and the extra friction heats, hardens and wears it until it leaks. Shaft speed adds to it, because a higher shaft speed raises the pressure in a sump that is not vented, so check the vent before asking for a pressure seal.
A seal built for pressure changes in three ways. The lip is stiffened, as on the TCV type, or backed by a cage that limits how far pressure can bend it, as on the TCN type, the backup design for higher pressure. The outside diameter is rubber-covered, because a rubber outside diameter keeps the bore sealed under pressure where a bare metal case leaks, and under high pressure the bore needs a retainer so the seal cannot be pushed out. NOK rates these designs for pressure and shaft speed together, so send both with the three dimensions.
The TCV page and the TCN and TCZ page give each design's surge rating. A rod or piston that strokes in and out under hydraulic pressure is a different job, covered on the hydraulic seals page. Send the part number or drawing and we quote it.
Sources: NOK Oil Seals catalogue 014E, Tables 3-1, 3-2 and 5-3, read 2026-09-16; Freudenberg Technical Manual for Simmerring® seals and rotary seals, Pressure, read 2026-09-16; Parker® Rotary Seal Design Guide, Catalog EPS 5350/USA, section 2, read 2026-09-17.
Oil seals for pumps, turbines, gearboxes and motors
On a pump or a turbine, a radial shaft seal works on the lubricated side: it keeps oil or grease in the bearing housing or gearbox and keeps water, dust and wash-down out. It is not the seal for the pumped fluid, which takes a mechanical seal, or for a turbine's steam or gas path. Shaft speed heats the lip above the oil around it, so the lip material is judged against the temperature at the lip, not the sump temperature alone.
Where a rubbing lip wears out too soon or costs too much torque, a bearing isolator is the non-contacting alternative: nothing touches the shaft, so nothing wears it. For a replacement, send the equipment make and model, where the seal sits, the shaft speed and the three dimensions, and we quote the seal.
Sources: Parker Rotary Seal Design Guide, Catalog EPS 5350/USA, sections 1 and 2, read 2026-09-17; NOK Oil Seals catalogue 014E, read 2026-09-16.
Seal types by standard designation
Most catalogs name a radial lip seal by two things: whether it has a dust lip, and whether its outside diameter is rubber-covered or bare metal. The letter codes below are the ones on most seal boxes; ISO 6194-1 numbers the same constructions instead of lettering them. A designation match is not a fit, form and function match, so confirm the three dimensions, the lip material and the duty before substituting one seal for another.
| Construction | Letter code | ISO 6194-1 type | Typical duty |
|---|---|---|---|
| Single spring-loaded lip, rubber-covered outside diameter | SC | Type 4 | Oil or grease, clean outside |
| Single spring-loaded lip, metal outside diameter | SB | Type 1 | Oil or grease, clean outside |
| Spring-loaded lip plus dust lip, rubber-covered outside diameter | TC | Type 4 with lip | Oil or grease, fine dust outside |
| Spring-loaded lip plus dust lip, metal outside diameter | TB | Type 1 with lip | Oil or grease, fine dust outside |
Grease and dust seals with no spring (V and K codes) have no ISO 6194-1 equivalent. The same letter can mean something else in another maker's scheme.
Sources: NOK Oil Seals catalogue 014E, page 8, read 2026-09-25; 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.
What to send for a rotary shaft seal quote
The three dimensions identify the size. The operating conditions decide which lip, case and material the quote names, so send them with the dimensions.
- Shaft diameter where the lip runs, in inches or millimeters
- Housing bore diameter
- Seal width, or the bore depth available
- Shaft speed in rpm, and whether the shaft reverses
- Pressure across the seal, or none if the housing is vented
- Temperature at the seal: lowest, normal running and highest
- Media: the oil or grease inside, and any dust, water or wash-down outside
- Lip material if the print names one, or the material of the seal being replaced
- The part number marked on the old seal, or the equipment make, model and part number, and the quantity
Send the list with the drawing through the request-a-quote form, or by email, and a Conquest representative replies with the quote.
Sources: Parker Fluid Power Seal Design Guide, Catalog EPS 5370/USA, 2007, 2008, Appendix A, read 2026-09-25.
Related pages
Viton is a trademark of The Chemours Company; Parker is a trademark of Parker Intangibles LLC; NOK is a trademark of NOK Corporation; Simmerring is a trademark of Carl Freudenberg KG. No affiliation or endorsement is implied.
Industries that buy radial shaft seals, rotary lip seals and oil seals
Frequently asked
Is an oil seal the same as a radial shaft seal or a rotary shaft seal?
In everyday use, yes: all three names describe a lip seal that runs on a turning shaft and keeps lubricant in the housing. Radial says the lip presses inward on the shaft diameter, rotary says the shaft turns, and oil seal says what it usually holds in. A seal that runs against a face instead, such as a V-ring, is an axial seal and is sized differently.
What do codes such as TC, SC or TB on a shaft seal mean?
They describe the construction. The first letter is the lip arrangement, S for a single spring-loaded lip and T for that lip plus a dust lip, and the second is the outside diameter, C for rubber-covered and B for bare metal. A TC seal is therefore a spring-loaded lip with a dust lip in a rubber-covered case, which ISO 6194-1 calls Type 4 with lip. Other makers use other letters, so confirm the dimensions and the lip material before substituting.
How do I measure a shaft seal for replacement?
Three dimensions: the shaft diameter where the lip runs, the housing bore diameter and the bore depth or seal width. Metric seals are usually marked with those three numbers in millimeters in that order, and inch seals with the shaft and bore in decimal inches, so the marking on the old seal is the simplest route. Note the lip orientation, whether there is a garter spring and whether the outer case is rubber-covered or bare metal.
What does the shaft surface need to be?
Hardened, plunge-ground and free of any machining lead, because a spiral lead acts as a pump under the lip and moves oil out past the seal. A shaft that is too rough wears the lip, and one that is polished mirror-smooth starves it of the oil film it rides on, so the finish is specified as a range on the drawing. Chamfer the lead-in and remove burrs, since a burr cuts the lip on assembly.
When is a PTFE lip chosen over an elastomer lip?
When the seal runs dry, at high shaft speed, hot or in chemicals an elastomer cannot take. A PTFE lip needs no oil film, so it suits dry-running shafts, and it survives solvents and acids that swell nitrile or attack fluorocarbon. The trade is that a PTFE lip is less forgiving of shaft damage and runout, and it is usually carried in a metal case rather than a rubber one. The seal maker's data sheet sets the temperature limit for a specific PTFE lip seal.
What is the difference between a single-lip and a double-lip seal?
A single-lip seal has one sealing lip facing the oil and is the standard choice inside a clean housing. A double-lip seal adds a second, unsprung dust lip facing outward to keep dirt, dust and wash-down water away from the primary lip; it is chosen for gearboxes, axles and pumps in dirty or outdoor service. The dust lip adds friction and heat at the shaft, so it is not used where speed or temperature is already at the limit of the lip material.
Can a worn shaft be resealed without machining it?
Often, yes. A thin stainless wear sleeve pressed over the groove gives the lip a new surface, or the replacement seal is chosen with a different width or an offset lip so it runs on unworn shaft. Send the shaft diameter and the depth of the groove and we quote whichever route fits.
Related guides
Send the shaft diameter, bore diameter and width
The three dimensions, the lip material if the print names one, the shaft speed and the equipment part number. A Conquest representative replies with the quote.
Request a quoteLast updated