An employee was moving 8 rail tank cars onto the main lead railroad line and was preparing to connect car 8 to the train. The employee entered the space between the train and rail car 8, facing the train, and went to manually open the knuckle on the coupling. His right hand was on the knuckle and his left hand was on the uncoupling lever. The employee's right hand was pinched between the coupling knuckles of rail cars 7 and 8, amputating the right hand at or near the wrist.