Hi, I'm looking into the possibility of making a small steam-engine, with focus on simplicity and low water-loss. Since I need high torque at low rpm, I don't think a turbine would be ideal, but would instead prefer something operating on the principle of "positive displacement", only the old-fashioned piston setup is rather complicated. Thus I am wondering if a gear-pump could be used instead of reciprocating pistons, the former being a much simpler construction than the latter, more so because it doesn't need valves timed to the rotation. Also a gear-pump should be much easier to make steam-tight than any piston/cylinder setup. I realize that a gear-pump (or rather "gear-motor") might not be very efficient, but at this time I can live with that (later on I might consider a more efficient design). Also it should be easy to make a two-stage engine, simply using two gear-pumps, one larger than the other, which might increase the efficiency a bit. Since the steam-engine will be recirculating the steam, and likely using a heat-exchanger to recover some of the waste heat, I'm hoping that a low efficiency in the motor won't be too detrimental to the overall performance. Any input on the feasibility of such a "gear-motor" design is welcome. Thanks in advance, Inventus.