Test results with a high speed four square gear test rig (nmax = 26 000 rpm) show the influence of speed,
viscosity, base oil, type and amount of additive on the scuffing load. In some cases at high speed the
scuffing load can be more than twice the value calculated according to ISO/DIS 6336/4. The reason for
the speed-dependency of the scuffing load is explained by the kinetics of the chemical reaction between
the metal and the additive. It is described, how a calculation method could take account of the high
scuffing load at high speed.