Love the look of this. Having seen it in RL, I know it is a much smoother colour contrast than this.

I suggest you get your hands on wither a black and brown wash. At present the working machines do meld quite a bit into each other. I can see you tried to soot the engine (a great addition by the way), but I think it needs more. I think that adding the black wash to the working machinery and a brown wash to the gold/brass parts the depth added would really help.