The oil seal (sealing ring) with Ø30 mm inner diameter, Ø40 mm outer diameter and 7 mm thickness (standard size 30x40x7) is a shaft sealing component used on gear motors and drive units of food-processing machines such as meat grinders, dough mixers and slicers.

Its function is to retain grease or lubricating oil inside the unit while keeping dust and debris out. As the sealing lip wears, or when the rubber hardens and cracks, the oil seal loses its sealing capability: typical symptoms are grease or oil leaking from the shaft, soiling around the drive area, or abnormal noise. In these cases it must be replaced with one of the same dimensions to restore the seal.