Contact conditions
The contact between the rollers and discs is similar to that which occurs in a ball bearing between the balls and the races. The traction fluid keeps the metal surfaces apart, ensuring that no wear takes place during operation, but the loads transmitted across the fluid are high enough to deform the metal surfaces elastically.
Improvements in computing power during the last 20 years have allowed advanced modelling techniques that have resulted in a more complete understanding of the contact conditions. Sophisticated models have been developed, allowing optimisation of the properties of both the fluids and the metal surfaces, such that premature failure modes have been eradicated and the ultimate fatigue life of the materials can be realised.