EMPLOYEES WERE ATTEMPTING TO MOVE AN ID FAN MOTOR. ONE WAS HOLDING A 2' LONG 4X4 WOODEN POST WHILE KNEELING ON THE FLOOR. ANOTHER WAS USING A SLEDGE HAMMER TO ALIGN THE MOTOR WITH THE ID FAN. A 10'X4"" HEAT SHIELD WEIGHING OVER 100 POUNDS FELL FROM THE IMPACT ONTO THE FIRST EMPLOYEE'S LEG.