4312 Lone Oak Road Nashville, Tennessee 37215.
This project began some 20 years ago when I acquired an old
derelict 3 HP Ottawa drag saw engine that was all apart and in
boxes with several broken and missing parts. At the time, it was
plainly beyond my ability to restore the engine to its original
running condition as a gasoline engine, so the boxes sat around in
something with them. As this engine used an igniter, there was this
neat passage from the outside of the cylinder block where the
device mounted, down into the combustion chamber. Now, I have been
building 1′ scale live steam locomotives and boilers for years,
so I know a little something about steam engines and that igniter
hole looked like a steam passage to me. Thus the idea of converting
the gasoline engine into a single acting steam engine was born. It
wasn’t difficult to design a simple piston valve to mount over
the igniter opening to admit steam to the cylinder for the full
length of the power stroke and to exhaust it on the outgoing
stroke. I figured that taking steam for the full stroke it would
still be using less steam than if it were double acting working
with anything more than a 50% cutoff. The valve body is welded up
from mild steel with a cast iron sleeve pressed into the bore. The
piston valve itself is turned from cast iron. I have found that a
cast iron valve running on a cast iron seat with lubrication will
last indefinitely.
The timing gear on the crankshaft was replaced with an eccentric
also turned from cast iron, and has a strap made from mild
steel.
Happily, the engine ran beautifully as a stationary exhibit on
around ten pounds steam pressure. It first ran as a stationary
exhibit hooked up to a large squirrel cage blower at the
Tennessee-Kentucky Thresherman’s Association show at Adams,
Tennessee in 1989, taking steam from their stationary boiler on the
grounds. Later that year I took the engine to a large show in the
northeast hoping to get hooked onto their steam line and running
there, but was disappointed at not getting encouragement or help at
all in doing this. As a result of this experience I was determined
that I would never take the engine to another show without being
able to supply my own steam.
Thus began the saga of the boiler. Early the following year I
began collecting proper materials for the project. A length of
12′ schedule 40 (?’ wall) SA 53 pipe for the shell; a piece
of 10′ schedule 20 ( wall) SA-53 pipe for the firebox; some
?’ SA-285 plate for the tube sheets and enough OD type K copper
tubing to make 43 flues, which were expanded with a tapered punch
into the tube sheets. Every treatise on boiler design will tell you
that a boiler needs a vigorous water circulation to be a good steam
generator. Well, looking at my drawing layout of the boiler, I saw
that there would be only a ? wide water leg space between the OD of
the firebox and the ID of the outer shell, and as the firebox
stands 12′ tall, I just couldn’t visualize much circulation
going on in this restricted area. So I hit on the idea of arranging
six external circulating tubes around the OD of the boiler shell as
you can see in the photographs. These are pieces of 2′ schedule
80 pipe that I split longwise and welded to the shell. There are
2′ square holes burned through the shell under these pipes, one
at the top about 4′ below the water line and one at the bottom
just above the mud ring. I call these circulating tubes, and
although I can’t prove scientifically that these tubes have
made this boiler the success it is, I can say I have never been at
a loss for steam. Water is supplied to the boiler by a ‘
Penberthy injector. In late 1990, I operated the engine and boiler
mounted on a small flat bed trailer at the Pioneer Power
Association tractor show in Eagleville, Tennessee.
But something was still missing. Heck, if I had the engine and
the boiler, why not mount them on wheels so I can drive around?
Thus began the collection of items needed for this phase of the
tractor project: a transaxle from an old Springfield garden
tractor, some 2′ square steel tubing for the frame, some farm
implement wheels found at roadside junk yards, a hand wheel with a
1′ Acme thread screw and nut attached from some piece of
industrial woodworking machinery to use for the steering gear, etc.
A couple of days on the drawing board arranging all these parts
together came up with what you see in the pictures. The 11 gallon
water tank on the back was formed up and welded from
3/16‘ black iron sheet stock protected
from rusting by coating the inside with a popular gas tank sealer
that is sold at most antique gas engine shows. Why did I make the
tank out of such heavy metal? Because that’s what I had some
of, and that’s the best reason there is! I made the steam and
exhaust connections from the boiler to the engine using high
pressure steam hose for both ease of fitting up and to eliminate
stresses that would be imposed on fixed piping due to slight
flexing between the boiler and engine. When I first got the engine
running I found out pretty quickly that there would have to be some
kind of canopy overhead as the water/soot/cylinder oil emissions
from the stack, until everything got good and hot, was making
driving the tractor a mite uncomfortable. Besides that, the wife
was beginning to get quite ill at me for ruining so many shirts!
The canopy is made from 1/8 pressed board
mounted on wooden formers and liberally coated with porch and deck
enamel. Driving the tractor is now a pleasure!
The boiler is coal fired with the coal being carried in a possum
belly under the seat and is shoveled from between my legs into the
firebox using a long handled kitchen spoon. In other words, the
boiler is ‘spoon fed.’ There is enough coal and water
carried to operate the tractor for about an hour. Folks sometimes
ask me why don’t I cut the water hopper off the cylinder. I
tell them, ‘That’s the mystique of the tractor.”
Besides, the remark most often made about seeing a gas engine
running on steam is, ‘Well, I’ve never seen that done
before!’ It’s just something to have fun with and I’m
enjoying it.
