A common application for grease-lubricated oscillating rolling element bearings is, e.g., rotor blade bearings in wind turbines. These bearings mainly operate under conditions that are prone to starvation. If the grease is unable to provide enough inlet lubricant supply for the contact between rolling element and bearing raceway, wear in the form of False Brinelling and thus premature bearing failure is possible. Bearing experiments with different lithium complex model greases, which differ mainly in their base oil viscosity and oil separation rate, were carried out to show the influence of the grease parameters on wear initiation. The results show that the ability of the grease to release a high amount of base oil with high mobility into the track of the rolling element is a crucial mechanism to prevent wear, especially at small oscillation angles. For oscillation angles larger than a critical angle, a secondary replenishment mechanism may prevent early wear initiation. The experimental results are used to validate a starvation model proposed in earlier work (Wandel et al. in Tribol Int 165:107276, 2022).

Traction in highly loaded elastohydrodynamic contacts is of great importance to reduce losses. The calculation of traction in these EHL contacts relies on the rheological models used. In this paper, results from traction experiments, which form an integration over Hertzian contacts with strongly inhomogeneous conditions, are presented. They are compared to data from laboratory measurements with homogeneous conditions. Due to the fact that the integral data do not directly represent local rheological fluid properties, further investigations are presented. Here, thermographic measurements are used to discern the contact temperature locally. Furthermore, a model for the maximum shear stress depending on pressure is proposed and compared to existing models.