5166 S. Vine Wichita, Kansas 67217
Isaac, my grandson, who is seventeen months old, is too small
for the other tractors I have built. I decided to build a tractor
small enough so that he could drive now and yet grow into it later.
Most of my Fun Scale tractors are red, so it was time for a new
color. After much thought the color green came to me. I have wanted
an unstyled John Deere B for a long time so that settled the type
of tractor. The size works out to about 1/4
Fun Scale; this is about as small a tractor as can be built and
still use pneumatic tires.
I felt that a gasoline engine had too much power for a little
guy like Isaac, so the next choice for a power source was electric.
The biggest problem was finding a motor big enough to have good
power and still fit in the frame. After much searching in car
salvages the only motor I could find was an electric fan motor for
the radiator. Several fan motors were tried but only one was felt
to have enough power to do the job. I do not know what kind of car
the motor I used came out of, because it was lying on the ground
when found. This motor is what I call a pancake motor. It is very
well built with ball bearings on both ends of the shaft and four
brushes. Maximum current draw is about 40 amps stall at 12
volts.
With the motor problem solved, a control system had to be
devised. A motor reversing switch was ruled out because of
complexity. I thought about using a three speed transmission but
felt it was also too complex and too heavy.
The next option was a forward reverse gear box from an old
riding lawn mower. This gear box gives some speed reduction and
will be a good shift trainer as Isaac grows older. Speed control is
obtained by using a nicrome coil resister for low speed and direct
connection for high speed. A garden tractor battery is used to
supply energy for the motor, duration of the battery is over an
hour and a half with a 50 pound youngster driving.
A small riding mower differential was used for the final drive
and rear axles. The rear rims are from 8 inch wheelbarrow wheels.
After cutting out the centers, a hub and spokes were welded in,
then 4.00 x 8 inch tractor tires were added. For front wheels, 2.50
x 4 inch tires and 4 inch rims were used. The frame is 2 x 2 x
1/4 inch angle iron. A motorcycle seat
was cut down for a seat. Steering gears came from a self-propelled
lawn mower transmission. The steering wheel was bent from ? inch
conduit on a tool I built.
Isaac hasn’t learned to steer yet, but he knows how to start
the tractor going. If I start out in low speed he reaches down and
pushes the speed lever too high. A desire for speed sure starts
young. Isaac really enjoys driving this tractor. He has a short
attention span but will drive for 30 minutes and I still have to
pry him off!
