INJURED WAS CLEANING ON 1ST NORTH HEADER WHEN HE WAS ATTEMPTING TO MOVE A DRIVE SPROCKET WHEN HE FELT A PULL IN HIS LOWER STOMACH. HE FINISHED SHIFT, WENT HOME, PAIN GOT WORSE, NOTICED A KNOT IN HIS LOWER STOMACH (EGG SIZE), WENT TO THE EMERGENCY ROOM AND HAD EMERGENCY HERNIA SURGERY.