PRESS RELEASE: ABS, in partnership with Vickers Oil and Imperial College London, completed a joint study on the use of environmentally acceptable lubricants (EALs) on stern tube bearings. The study evaluated EAL properties relative to mineral oil-based lubricants and concluded oil viscosity is the primary property in selecting an EAL.
- viscosity of EALs is more stable than that of mineral oils, with respect to changes in temperature
- EALs demonstrated relatively lower pressure-viscosity coefficients than mineral oils, indicating EALs may form thinner oil films, potentially insufficient to protect surfaces from wear under edge loading conditions
- using EALs with higher pressure-viscosity coefficients, compared to other EALs of the same viscosity, may provide some safety margin in shaft-alignment sensitive installations
- EALs may offer less margin in shaft misalignment conditions, therefore particular attention should be taken for correct shaft alignment
- using EALs with higher viscosity, compared to a mineral oil of lower viscosity, may provide additional tolerance for edge loading wear.