Technical Committee Lubricants

Investigation of Load Carrying Capacity of Gears Lubricated with Gear Greases NLGI 0 and High Viscosity Fluids

In this research project the influence of flow greases NLGI 0 on the load-carrying capacity of gears and different base oil viscosities of greases and fluids as well as their impact on gear failures are systematically investigated. The base oil shows highest coefficients of friction and retention time of the lubrication film, lowest wear and matching results with the calculation method DIN 3990 / ISO 6336 for pitting load-carrying capacity. With higher viscosity adjusted by an increasing portion of VI-improver PMA of fluids, lower coefficients of friction and retention time of the lubrication film, no advantages concerning wear and pitting strength, but higher pitting life time can be observed. Greases cause highest wear, lowest pitting life time and retention time of the lubrication film. In total, greases show big disadvantages concerning load-carrying capacity compared to fluids. The high viscosities of fluids are not necessary for high retention time of the lubrication film and low wear, but show advantages for pitting life time. For the calculation of the pitting load-carrying capacity according to DIN 3990 / ISO 6336 and for the calculation of the wear characteristics according to Plewe variables of the investigated lubricants are available including the influence of lubrication with greases NLGI 0 and high viscosity fluids.

The IGF project (16222 N) of the Research Association for Petroleum, Natural Gas and Coal was funded by the Federal Ministry of Economics and Technology via the AiF within the framework of the programme for the promotion of joint industrial research and development (IGF) on the basis of a resolution of the German Bundestag.