oil seals
The purpose of oil seals is to provide sealing between the rotating crankshaft and the outside. Classical oil seals consist of a metal housing that carries the dynamic sealing lip and also provides the static sealing function. The sealing lip of oil seals is usually manufactured of elastomer material, and is in contact with the surface of the rotating shaft. Hereby, the lip is pressed onto the shaft surface by means of a spring ring. As a result of the rotational movement, there is a sealing gap of approx. 1 μm at the lip edge. Oil can enter this gap, which serves to lubricate the sealing lip.

The material for future oil seals is named polytetrafluoroethylene – or simply PTFE.

Low friction and minimum power consumption are the decisive advantages offered by PTFE oil seals. These seals can be used without problems also with dry operation or insufficient lubrication. The material’s excellent thermal properties, with an operating range of -130ºC to +200ºC, are unrivalled. Moreover, PTFE is featured by high chemical resistance and a low breakaway torque after standstill.

Integrated oil seal Design and Construction
The outer housing is made of stainless steel. An O-ring of fluoroelastomer ensures optimal static sealing. The internal diameter is perfectly concentric with the outer diameter. The actual sealing lip is made of highly wearresistant and low-friction PTFE. An additional dust seal (rubber lip or felt strip) provides an effective barrier against contaminating particles.

Special Type With Integrated Oil Seal
Integrated oil seals reduce the manufacturing time of series production engines. As only one component needs to be installed, work on the assembly line as well as subsequent leakage is reduced by about one third. Similarly, significant time savings are achievable when replacing the radial crankshaft seals.

TIP FROM THE EXPERTS

Damaged PTFE Sealing Lip
The most frequent cause for failure is damage to the PTFE sealing lip during assembly. If the seal is installed without the help of a sleeve or special tool, and is shifted or even turned inside out, reliable sealing will hardly be possible. Similarly, the use of oil or grease – as with classical oil sealing rings – will result in total failure of the PTFE oil seal immediately after installation.