John Deere model R Two Cylinder Diesel Tractor







In 1935 Deere saw the need for a tractor that was: to replace the
John Deere Model D Tractor with increased power, and had a diesel engine.

Diesel engine technology was just beginning, so work began with
experiments on stationary engines. By 1938 two Model D gasoline
engines were converted to diesel but were later scrapped.


By 1941, eight Model MX tractors of a new design had been developed.
Three more years of testing and refining produced five MX tractors
in 1944.

Again, it was three more years of tests and refinements before in
1947 the final lot of eight MX tractors were ready to become the
finished John Deere Model R Tractor.

1939 - 40 John Deere experimental Model R...the MX





But it wasn't until January 12, 1949 that Deere's dreams finally came
true when the first John Deere Model R Diesel Tractor rolled off
the production line.

When it was tested at Nebraska, the Model R set an all time record
for fuel economy.


John Deere Model R 1949 to 1954


The Model R Tractor accomplished 3 firsts for a John Deere tractor:

1. It was Deere's first diesel tractor.
2. It was the first Deere tractor with a live PTO.
3. It was the first Deere tractor to be equipped with a cab.



John Deere Model R, having a bit over factory specs.....



Advertisement from 2 Cylinder Diesel Shop




The pony motor that started the main diesel engine was a two cylinder
opposed gasoline engine with a bore and stroke of 2.6 x 2.3 inches,
it would make 4,000 rpm, had a 6 volt electric starter and was cooled
by the main diesel engine cooling system, it was mounted on top of the
main engine's crankcase.


The exhaust from the pony motor was routed back through the diesel
engine to help warm up the cylinders for better cold weather starting.
The pony motor had about 9 horsepower.


The compression ratio on the Model R was 16 to 1. The high compression
ratio also caused compression temperatures of around 1000 degrees in
the cylinder thus auto igniting the diesel fuel.


The original Model R was rated at 45.69 drawbar and 50.96 belt horsepower
weighed 8760 pounds, and had a 5 speed transmission. The crankshaft
weighed 207 pounds, bore 5 3/4, stroke 8 inches, 416 cid, engine speed
was 1000 rpm, the tractor weighed 7400 pounds at the factory.


Two Scintilla injection pumps were used delivering fuel under the
pressure of 2400 pounds per square inch. This resulted in a cylinder
firing pressure of 875 pounds per square inch and gave a load of
22,750 pounds against the aluminum piston.



A more traditional John Deere Model R doing more the
kind of work the factory intended it to do.... shown here
pulling a John Deere No. 36 Combine





All Model R's were built only as standard tread tractors.

The live PTO and hydraulics were options, although because of the gearing
used to drive these systems, if you ordered one option the other had to
be ordered also. In late Model R's there was a special heavy duty
transmission available as an option which reduced 3rd, 4th and 5th
gear speeds, however records don't indicate that any R's were ever built
with this option.

The price of a new 1954 Model R was $3,650.
Some 17,000 Model R's were manufactured during it's stay in the long
green line.

The Model R could plow 40 acres in 12 hours using 25 gallons of fuel,
in contrast the Model D it replaced would take 24 or more hours to do
the same work and used twice as much fuel.


The last time any Deere horse drawn equipment was offered for sale was 1954.

The first diesel tractor (crawler) mass produced in the U.S. was the
Caterpillar Diesel 65 in 1931. It had a pony motor for starting. In
1932 International brought out their first diesel, the McCormick
Deering T40 Diesel (crawler). It was started on gasoline, then
switched over to diesel fuel.

In 1935 this engine was put in the International Harvester WD 40
which was the world's first diesel tractor on wheels.



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