Radial shaft seals are frequently used in power transmission systems to prevent oil leakage. The importance of these components for operational reliability provides a great challenge for the industry. Oil leakage from power transmission systems not only has a negative impact on the environment but can also affect the product quality and customer satisfaction. Pertinent design and standardisation of key surface parameters such as surface texture and machine lead angle or shaft lead are paramount. The former is an inherent property of any surface, which is also commonly referred to as surface roughness whilst the latter is formed during manufacture of the shafts. The often contradictory objectives of efficiency, effective sealing and reliability require a combined numerical and experimental approach. A numerical model accounting for surface interactions and hydrodynamic flow in the mixed regime of lubrication will be created. The numerical model will be used to understand the underlying physics and inform design. In parallel, a component level test rig is created to experimentally validate the numerical model and to benchmark new components designs. Additionally, new standards will be created to characterise the waviness and roughness of the contact surfaces measured using optical interferometers.

The research utilises extensive use of metrology equipment such as optical microscopy, white light interferometry to assess the surface topography of the sealing pairs. The research also involves use of sensors to monitor the performance in-the vehicle and also in the developed test rigs under this research programme. Computational models are also developed for an in-depth understanding of the details of the leakage mechanism.

The research has so far highlighted the impact that the utilised manufacturing methods in industry can have on the radial lip seal performance. It is shown that the certain machining methods used in manufacturing can influence the leakage rate and power loss from radial lip seal conjunctions.

Some of published work from this research are:

• Kozuch, E., Nomikos, P., Rahmani, R., Morris, N. and Rahnejat, H., 2018. Effect of shaft surface roughness on the performance of radial lip seals. Lubricants, 6(4), p.99.
• Nomikos, P., Kozuch, E., Morris, N.J., Rahmani, R. and Rahnejat, H., 2018. Measurement of vibrations affecting the power transmission seals. 4^th Biennial International Conference on Powertrain Modelling and Control (PMC 2018), Testing, Mapping and Calibration, September 10-11, 2018, Loughborough University, UK
• Kozuch, E., Nomikos, P., Morris, N.J., Rahmani, R. and Rahnejat, H., 2018. Performance evaluation of radial shaft seals of automotive transmission systems. 24^th International Conference on Fluid Sealing (FS 2018), 7^th – 8^th March 2018, Manchester, UK
• Kozuch, E., Nomikos, P., Morris, N.J., Rahmani, R., 2018. Evaluating leakage from radial lip seals affected by bearing area of shaft topography. In 20^th  ISC International Sealing Conference Stuttgart 2018: Sealing Technology, Beyond Limitations, University of Stuttgart, October 10-11
• Kozuch, E., Nomikos, P., Morris, N.J., Rahmani, R. and Rahnejat, H., 2018. Shaft surface as a factor affecting lip seal performance. TriboUK 2018, University of Sheffield, 12^th-13^th April 2018