Technical Committee Lubricants
Investigation of Lubrication and Load-Carrying Capacity of Gears Lubricated with High Consistency Gear Greases
This research project gives an initial overview of the lubrication of spur gear drives with
greases NLGI 1 and 2 concerning lubrication supply, efficiency and load-carrying capacity of
gears. Based on rheological and tribological investigations, the film formation properties of
different model greases, which are based on different base oils and thickener types, are
investigated in an EHL-tribometer. Basic studies at different operating conditions and fillings
were performed in a FZG back-to-back test rig analyzing lubrication supply, efficiency and
load-carrying capacity. Based on these results of comprehensive investigations with greases
NLGI 1/2 in the FZG back-to-back test rig, two different lubrication supply mechanisms can
be basically defined: Channelling and Circulating. Whether Channelling or Circulating occurs,
depends on different factors like the interaction of torque, speed, filling level and type of
grease. Based on the experimental results, recommendations are made for gear and
gearbox design for grease lubrication with NLGI 1/2.
The IGF project (15883 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.