Show Cruiser

By Staff
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The completed Fairmont/Simplicity tractor showing the flat belt, belt tensioner and jackshaft pulley. Also shown is the clutch lever (orange knob) and shift lever (black knob).
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The underside of the Simplicity showing the jackshaft v-pulley and bearings, belt guide roller and brake cable.
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Lowering the Fairmont Series B onto the Model 728 Simplicity’s chassis.
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The Fairmont/Simplicity sporting its new headlights
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Powered by the Honda passenger car alternator

This little tractor is the combination of a
1944 Fairmont railroad section car engine and a 1972 Simplicity
Model 728 garden tractor. I restored the engine 30 years ago after
finding it in Minneapolis. It had been resting on its flywheels on
the floor of a garage for some time and was quite dirty. I was a
little surprised when I gave it a push and found the flywheels
would turn. Immediately interested, I asked if it was for sale. A
few minutes and $30 later, I became a Fairmont owner.

I could hardly wait to place a call to Fairmont Railway Motors
in Fairmont, Minn., to ask some questions about my new engine. The
serial number, 66252, was all they needed to tell me the engine was
a 1944 Model QBA, Series B, sold to the Minneapolis and St. Louis
railroad in 1944. This was exciting! Back in 1944, we used to
listen to the section cars, “putt-putts” we called them, go through
our hometown of Lindstrom, Minn. The Great Northern tracks were
only a couple of hundred feet from our house.

The restoration of the engine was made easier because nothing
was broken and it had very good compression. The two rows of ball
bearings on the pulley end of the crankshaft and the one row on the
other end didn’t seem to have excessive play, so I didn’t have to
remove the flywheels and crankshaft. After cleaning and sanding it
thoroughly, I gave it a shiny new red and yellow paint job. I had
the cast aluminum water hopper sandblasted by a local abrasive
blasting company. The cast aluminum carburetor just needed to be
cleaned inside and out. All the ignition parts were okay. An oak
cradle now supports the gas tank between the flywheels over the
crankcase. Often on section cars the tank was mounted on the
chassis of the car, next to the engine.

Fairmonts use a Model T Ford-type buzz coil for ignition, and as
luck would have it, one of the two coils in my engine stuff was
painted gray and stamped on the side with “Fairmont Railway Engine
Co.” I mounted the engine on a wood base with a box on one end for
the coil and a 6-volt battery.

Ready to Run

I gassed it up with some 2-stroke mix, squirted some oil into
the main bearing oil cup on the pulley end of the crankshaft, and
closed the ignition knife switch. With the spark retarded about 10
degrees and one hand on each flywheel, I pulled it slowly through a
couple of cycles. There was no turning it fast, because with 84
cubic inches of displacement, getting it over the top just once is
an achievement. On about the third or fourth try, the old 2-stroke
fired up with a real loud “Fairmont bang.” The thrill I get when
one of my engines starts for the first time is so exciting I just
stand there and laugh. With no pipe or muffler it was very
loud.

A month or so later, my wife and I took a trip to the Fairmont
Railway Motors Co. We were warmly received and congratulated in
obtaining one of their engines. They gave us a very thorough tour
of their manufacturing facility, including the aluminum, cast iron
and brass foundries. They also presented us with a brand new
owner’s manual and several gaskets they thought might come in
handy.

For the next 30 years or so, I started the engine now and then
just for fun. People within a block or two would hear it and
sometimes come to watch.

The Fairmont needed some kind of wheels, so after being inspired
by seeing a garden tractor at the Almelund Threshing Show sporting
a hit-and-miss engine, I decided to find a tractor for my engine. I
didn’t have to look very far – one of my K-Mart breakfast buddies
in the small engine and garden tractor repair business happened to
have a 1972 Simplicity Model 728 without an engine. What luck!

I bought the tractor and immediately got to work removing the
parts that weren’t needed with the new power plant. I took parts
off right down to the bare backbone of the little tractor, so all
that was left was the front suspension at one end and the 3-speed
cast iron transaxle on the other. I removed a lot of accumulated,
oily, caked-on dirt with a screwdriver, then scrubbed the whole
thing with solvent and a product called Melaleuca MelaMagic, a
household cleaner. Without all the dirt it looked pretty good.

It took quite a few additional hours of prepping the tractor for
its new paint. After I had the Simplicity Orange paint laid down,
the tractor’s chassis and sheet metal rear fender looked like new.
I also cleaned all four wheels and painted them silver. The rear
tires were still serviceable, but the front ones needed to be
replaced.

The chassis needed four new holes to mount the Fairmont.
Fortunately, the exhaust port on the bottom of the engine lined up
with the hole in the chassis where the vertical crankshaft of the
original engine passed through.

Getting Control

Now the task at hand was to design and make all the necessary
parts to control the engine and get the power from its flat pulley
to the v-pulley on the tractor’s transaxle. I also had to come up
with an exhaust system that would tame the Fairmont’s loud
exhaust.

The throttle and spark advance are controlled by rods visible in
the photos. The drag on the spark advance is built into the engine.
The drag on the throttle is created by the force of a tension
spring dragging on the control rod. The exhaust pipe required a lot
of thought and could not be dealt with until the jackshaft and
drive belt path on the bottom of the tractor could be
determined.

I turned the 4-inch crowned belt pulley for the jackshaft from
aluminum stock. After experiencing some belt slippage, I added
rubber lagging held on with screws and 3M Scotch Grip 1300
adhesive. The 1-inch diameter jackshaft runs on ball bearings at
each end and has an 8-inch v-pulley in the center. The aluminum
belt tensioner also runs on ball bearings pressed into each end.
The tractor is articulated, so it has a longitudinal roller bearing
structure in the center of the chassis. In order to route the lower
part of the 86-inch v-belt from the jackshaft over the roller
bearing structure to the input pulley on the transmission, I
installed an aluminum roller running on ball bearings ahead of the
structure. The tractor’s belt tensioner pulley runs on this belt
for clutching purposes. This pulley is controlled with the lever
next to the steering column and can be operated either by hand or
foot. Squeezing the brake on the clutch lever actuates a caliper
that stops the input pulley of the transmission for clash-free
shifting.

A cable attached through a pulley system to an arm on a common
brake pedal shaft actuates the stock brake band on the
transmission. Both foot pedals rotate the brake shaft.

I raised the seat 7 inches and moved it back about the same
amount to keep the driver a comfortable distance from the engine.
The batteries and coil are located in the box that serves as the
seat riser. It was also necessary to lengthen the steering column
and move it back.

The muffler is a replacement for a small Ford car and came with
a convenient flange on the inlet pipe. Inch-and-a-half galvanized
pipe makes up the exhaust pipe between the engine and the
muffler.

Since its “completion,” I have installed a Nippondenso
alternator from a Honda passenger car to supply power to the
headlights and tail light I added. The alternator runs at 1,200 RPM
at idle. I arrived at the alternator speed by installing a
4-1/2-inch pulley on the jackshaft and a 2-inch pulley on the
alternator. I then installed a belt tensioner to keep the belt from
slipping. Because the coil for the Fairmont operates on 6 volts and
the excitation for the alternator and lights operate on 12 volts, I
am using two 6-volt motorcycle batteries running in series with the
alternator across both of them and the buzz coil across just one of
them. I also installed a choke for easier starting in these cold
Minnesota winters.

It took me a little over a year to make the conversion. I spent
many hours in my machine shop designing, fabricating parts and
painting. I had a good time driving the tractor in six tractor
parades, and just here and there during the 2004 season. Show goers
really get a kick out of how the engine rotation can be reversed on
the fly. Because first gear has a much higher ratio than reverse,
I’m sometimes seen backing up in first gear with the engine going
backwards to keep the speed down.

Contact engine enthusiast John L. Magnuson at: 4640 Ensign Ave.
N., New Hope, MN 55428; (763) 533-5787.

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