Technical Committee Lubricants

Load-carrying Capacity of Gears with Grease Lubrication

In this research project the lubrication film formation of gear greases in the EHD-contact, the influence of grease lubrication on the load-carrying capacity of gears and different lubrication principles of greases are investigated systematically.

Grease and its base oil build up same film thicknesses and show same wear characteristics. The pitting life time and the scuffing load-carrying capacity of greases is slightly lower than that of the respective base oil. For greases the film thickness, the scuffing load-carrying capacity as well as the pitting life time and the pitting load-carrying capacity correlates with the base oil viscosity conspicuously. The addition of a special synthetic graphite as solid lubricant shows very high wear in this research project.

For greases the base oil viscosity is decisive for the calculation of the film thickness according to Ertel/Grubin with correction according to Murch/Wilson and for the calculation of the pitting loadcarrying capacity according to DIN 3990. For the calculation of the scuffing and pitting load-carrying capacity according to DIN 3990 and for the calculation of the wear characteristics according to Plewe variables of the determined lubricants are available including the influence of grease lubrication.