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The unique demands of down-sized cars on the engineering departments of spring strut manufacturers have forced their seal suppliers to design new rod seals. The spring loaded lip seal is now a standard element of Mc Pherson struts. An improved lip seal design with a lubrication groove provides even better riding comfort for the new generation of lighter cars.

The stringent requirements in regards to reliability and lifetime of the entire truck have to be applied to the seals as well. This paper will only deal with oil seals used for driven truck axles. Generally there are two sealing applications, the pinion and the wheel (picture 1). A very special feature, which distinct the truck axles from various other aggregates is the lubricant for the system, being ‘EP’ (Extreme Pressure) oil. These oils can have a tremendous impact in the sealing performance of the oil seals under the given application conditions. Another speciality for truck axles is the nature of contamination from outside having an impact on performance and life of the seals. The more details that are available at the design stage of the seal, the better the decision for an optimal seal design can be made.

This paper discusses the engineering aspects for the application of PTFE or elastomeric radial shaft seals in the automotive industry. Primarily considered are frequently used materials compared to PTFE, the sealing lip contact of the seal on the shaft, the frictional torque as well as important functional operation differences between elastomeric and PTFE radial shaft seals. Finally, a description of various design versions are given to portray the actual PTFE radial shaft seal program.

The rubber industry provides special oil seals from elastomeric materials to seal pressurised shaft applications. Normally these are small and simple looking devices, which can tolerate quite complex conditions. The design of the seal has a tremendous impact on good performance. Basic parameters for pressure oil seals made from elastomeric materials will presented. Application conditions must be balanced to the degree of seal stress. For example the right compromise has to be chosen for flexibility and stability of the lip section. The heat which is generated by friction must be dissipated through the shaft and the medium to be sealed. Medium and elastomeric material must not be overloaded thermally. The product of pressure and surface speed (p · v) is an important characteristic for the evaluation of how much a seal is stressed. A graph of achievable ‘p · v’-figures will be presented.

Newly extended warranty periods in combination with lower temperature requirements, anti-skid brake systems, and the introduction -of gas type dampers, have created new demands and problems for shock absorber seal suppliers. Herein are described special material and design solutions for low temperature, pressurised and un-pressurised, mono-tube and twin-tube damper applications.