This is the best small steam engine around. It is available as a casting kit from Gary Hadden up in Holly, Michigan who has been making these little engines for years. He has successfully run both steamboats and small steam vehicles with them. This is the 3” bore and 3” stroke engine, double acting.
Before explaining the fine features of this engine that make it the best design around one needs to know what the competition is for small, meaning 5 hp to 20 hp steam engines. Most available casting kits are old fashioned sliding (also known as “D” valve) engines with harmonic drive to the valve train. Much better are piston (also known as “spool” valve) engines. The best are poppet valves. There are other issues that have to do with uni-flow, counter-flow, and clearance volume, and cutoff control.
It would take a book to explain all of the subtleties of steam engine design and what we are doing here is simply making a bald statement of what I have learned.
This engine is double acting uni-flow with a three-dimensional cam, roller cam followers, and poppet valves. The crank system is exposed using the rod frame design and using sealed ball bearings. The crank throws are over-hung with a chain sprocket in the middle of the crankshaft.
In consequence of these design decisions the engine has the greatest potential for thermal efficiency of any other contemporary available steam engine. It is also designed to be fairly low revving and using low pressure steam of about 200 psi. The over-hung crank design is not all that strong and the connecting rods are cast aluminum and so the engine is not designed for heavy high pressure use. Of course it can always be engineered differently with more time and money.
The 90 degree cranks are intrinsically impossible to balance. Therefore above 1,000 rpm there is a lot of shaking. However, this is designed to be self-starting, a very important steam engine feature.
The three-dimensional cam means that by moving the shift lever the engine can run forwards and backwards and be varied from low to high torque at any time.
This is a good place to start for any small backyard or small steamboat or small Locomobile-type of road vehicle. It will put out 10-15 horsepower. The water rate should be close to 10 pounds and should be compared to a Stanley steam car water rate of close to 30 pounds. When pounds of water rate are bandied about by steam people what is meant is the amount of water that needs to be boiler per hour to produce one horsepower. It is a common, although approximate, method of showing thermal efficiency.
This is a portable steam engine at the Willits Steam Museum in Northern California. You can tell that it is not a traction engine because the rear wheels do not have lugs on them and there is no steering mechanism. This thing was pulled around by horses to provide power for threshing. Back when this was made they had not invented electricity and so everything had to be riveted together. Only solid fuel was available, either wood or coal. This is very old technology and very little of that technology is of any value today.
December 2013 Here we are making steam on a cold winter day and making fire, same day. This is our motorcycle boiler 4 1/2 gallon/hour kerosene Beckett gun burner and about .8 gallons of water per minute for almost 500 pounds of steam an hour at about 500 psi and 800 degrees F. We are adjusting the controls at this time and sometimes the steam temperature fluctuates. They tell me this happens a lot when a person does not know what they are doing with a monotube boiler. The fire is unintended. We have extra cooling air blowing around the combustion chamber and so there is a lean burn. There is an extra nozzle in there so that at speed we can turn on a switch to the fuel solenoid and add a couple more gallons per hour of kerosene, sort of as an after burner. It appears that when we overheated everything the last run, due to forgetting to hook up a ground wire and thus not pumping water for a few minutes until everything glowed red hot, the nozzle melted off the fuel line. Thus instead of through a small atomizing nozzle we had fuel going in through a brake line. At least we had good ignition. This fuel delivery system needs to be perfected before we sit astride the motorcycle. More testing is in the program. Tom Kimmel
This is a Doble auxiliary engine designed for F-31 that was not used for such. It is double acting compound piston valve. HP is 1.531 inches, LP 2.575 inches and stroke is 2.00 inches. Engine has ball-bearing mains. Valve stroke is 25/32 inches maximum but there is a slip-feature eccentric for reversing and hooking up. The high pressure cylinder is jacketed to receive exhaust steam from the HP cylinder before it goes into the receiver to go to the low pressure cylinder. The piston valves are hollow with the center-cored passages allowing exit of exhaust steam which cools the valves. The very large diameter flywheel/ring gear is for driving a generator.
Here are Doble “F” engines from the Besler years at the Doble factory. These were designed by Stanley Whitlock and most of them were sold overseas, mostly to Germany in the 1930’s. You will note the piston valves between the HP and LP cylinders. These photos are courtesy of Fred Lothrop and very valuable because this information is not elsewhere available.
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