Limiting Load for scoring and coefficient of friction, in the case of carburized and hardened steel, under various contact conditions of simultaneous rolling and sliding, were studied. Their characteristics were tested, changing widely the lubricating oils, sliding velocity and specific sliding. We got an approximate formula about the limiting load for scoring as a function of sliding velocity and specific sliding. The critical temperature rise by Blok was also discussed with our experimental results. Moreover we have compared the limiting load for scoring by means of FZG spur gear test and 4 ball test with our experimental results by means of our disk-machine.