I am a locomotive engine, and can draw a train after me, from morning to night, at th

I am a locomotive engine, and can draw a train after me, from morning to night, at the rate of from ten to sixty miles an hour. I can also pull up a steep incline, and can go round a sharp curve. In fact, I can go anywhere, and do anything. I am strong, but not too strong, and swift, but not too swift. I am made to work, and I work hard; but I am not made to fight,