EE WAS OPERATING A 637 CAT SCRAPER IN QUARRY. EE WAS ATTEMPTING TO INITIATE A HOOK AND PUSH OPERATION WITH ANOTHER SCRAPER, WHEN HIS PUSH BLOCK RODE UP ON PUSH BLOCK OF OTHER SCRAPER CAUSING H IS FRONT WHEELS TO COME OFF GROUND, WHEN FRONT SCRAPER PULLED FORWARD, EE'S SCRAPER DROPPED BACK TO THE GROUND.