An NOK oil seal interchange is a component designed by the NOK Corporation to seal lubricants. It prevents liquids or gases from leaking through a joint or from allowing dirt to enter the moving components of a machine. The interchange consists of a sealing element, metal case and a spring.
The seal has a flexible lip that rubs against a shaft rotating inside a housing or bore to prevent ingress of fluids and dirt. Oil seals are used primarily for rotary applications only.
Suzuki Cars mentions single, double and triple lip oil seals as the available types in the market. For proper installation, the seal lip should point towards the medium being contained.