FIELD MAINTENANCE TECHNICIAN WAS USING 2 1/2"" BOLTS TO ATTACH THE PROPEL TRANSMISSION TO THE CARBODY OF A SHOVE. THE HYDRAULIC TORQUE WRENCH SLIPPED OFF THE NUT BEING TIGHTENED AND STRUCK HIM IN THE MOUTH LACERATING HIS LIP. HE RECEIVED 5 SUTURES IN HIS LIP.