I have a lot of books and design info on all the other aspects of steam engines, but only a little on balanced valves and governors. Any Books available? Old technical drawings? I have some idea of the basic design but would like detail on valve shaft seals and such. I have heard of using a hydraulic spool valve for steam but I know they are not made for the high temp or the lack of lube. I suspect they'd fail quite soon if not real fast. I need one that'll run for years.