The Oil Seal 18x40x7 NBR TC is a TC rotary shaft seal sized 18x40x7 mm (ID × OD × width). It keeps oil inside and dirt outside on a 18 mm shaft seated in a 40 mm bore — a size common in small electric motors, power tools, pumps and instrument gearboxes.
Dimensions & specifications
| Inner diameter (shaft) | 18 mm |
| Outer diameter (bore) | 40 mm |
| Width | 7 mm |
| Seal type | TC — double lip, rubber covered, garter spring |
| Material | NBR – Nitrile |
| Temperature range | -30 °C … +100 °C |
How the TC design works
The TC arrangement — rubber-covered case, garter-spring main lip, external dust lip — is the industry’s go-to solution wherever a shaft spins in an oil-filled housing.
About the NBR nitrile compound
NBR nitrile rubber gives the lip its resistance to mineral oils, greases and hydraulic fluids — exactly the fluids a gearbox or pump seal meet. It is the industry’s general-purpose choice; just keep it clear of brake fluid and direct sun when storing.
Should the shaft read slightly below the listed size — typically a few tenths of a millimetre — no concern: the lip’s interference fit accounts for it.
Buying & shipping information
- Individual pieces, no minimum order — checkout in US dollars.
- Our prices do not cover customs duties or taxes your country may apply; those fall to the buyer.
- One worldwide flat shipping fee · every parcel tracked, number emailed.
- Before you buy, confirm the fit: measuring guide or free dimension check.


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