Scoring in Spur Gear Pairs (2nd Report, Scoring Temperatures in Case of EP Oils)

As a basis for establishing a calculation method of the scoring load capacity of a spur gear pair the relation of the scoring occurrence to the temperature and the correlation between the gear test results and the two-cylinder test results were examined for EP oils using an IAE type high-speed gear test rig. An increase in the chemical reactivity of the EP oil causes an increase in the anti-scoring capacity of the EP oil. Unlike the maximum value of the maximum contact surface temperature and the integral temperature, in the mixed lubrication state, the working flank bulk temperature just before scoring is affected by the rotating speed to a lesser extent. Also in the EP oils, as in the gear base oil, the scoring temperature of a spur gear pair in the mixed lubrication state can be estimated by the outer surface bulk temperatures just before seizures in the two-cylinder tests taking the specific sliding and the sliding velocity at the beginning or the end of gear meshing into consideration.