<b>Radial Shaft Seal</b> Radial shaft seals are lip seals, with the primary sealing lip resting radially on a rotating part. The classic, best-known and very frequently used element of this group is the elastomer radial shaft seal, also commonly known as the Simmerring (oil seal ring). With a good lubricating fluid, optimal flushing and a suitable material, radial shaft sealing rings can be used up to 35 m / s sliding speed. The sealing effect of the radial shaft sealing ring is based on an elastohydrodynamic return effect. This is based on the two different sealing edge angles and α and β and a characteristic contact surface wear. The liquid to be sealed must always be on the side with the larger sealing edge angle α. If liquid is offered on the side with the smaller sealing edge angle β, it is pumped to the side with the larger sealing edge angle. Radial shaft seals are therefore active sealing elements and can therefore seal without leaks.