I am a locomotive engine, and can draw a train after me for any distance, at any spee

I am a locomotive engine, and can draw a train after me for any distance, at any speed, from ten to sixty miles an hour. I can also pull up sharply, when required. I can go round any curves, and up steep gradients. In fact, I can do anything on rails, except fly. I am strong, but not too strong, and can be made to fight my own weight. I am steady, go where I will, and can be