Just how necessary the simmerring or radial-shaft-seal is, can best only be seen when it's defective. An unsuccessful attempt at replacing a leaky seal, shows how careful one must be when installing one. The really important factors in this case, are the surfaces than rub against each other. On the sealing-ring side there is a prefabricated sealing-lip which has a slight structure. That this the actual sealing-side is, is a foregone conclusion.

One should however, also pay attention to the surface of the shaft. Should it be a bit too rough or if indeed, it has grooves, then it's a waste of time carrying on with the repair job. It may also be so worn down, that the ring-spring and thus, the pressing force is too weak. Only in the case of certain veteran cars, can/should the spring be shortened by a few millimeters.

Of course the shaft bearing is also important. If the bearing has too much play, then a new simmering is not going to solve any problems. It is particularly important that the seal is evenly pushed on, until it reaches its final seating all the way round. Whether it is tapped- or pressed on, doesn't matter, the pressure must be evenly distributed over the whole of the metal casing. One should determine beforehand, whether it should be installed dry, or using a sealing compound. If one uses a component where the seal is already fitted, this question is obsolete (see picture 3).

As far as the sealing ring is concerned, it makes little difference whether it's installed in a static casing or in a rotating part (see picture 7). Very often it is firmly integrated, e.g., in a wheel bearing (see picture 5). The metal core is also used for magnetization (see picture 6). The only thing still missing, is the sensor. The shaft to be sealed may have not only a rotary movement, it may also move back and forth (translational) (see picture 4). 04/12