The Model R

J.R. Hobbs

Orignally Published in Green Magazine, June 1994

Reprinted here with permission

As the 1920's drew to a close, several companies began to explore the possibilities of a diesel engine for farm tractors. The compression-ignition oil burning engine conceived by Rudolph Diesel in 1892 had been a success, but early versions had been huge, requiring massive parts to insure reliable operation, and huge cubic inch displacements to provide even rather meager power outputs at very slow speeds. As knowledge and metallurgy advanced, it became possible with better metals to produce diesel engines that were more compact, powerful, and efficient. The advantages of the diesel engine, such as excellent efficiency, low cost of operation, and excellent power and torque curves, were well known, but so were the disadvantages. Diesel engines, due to necessarily high compression ratios, were difficult to start in any kind of weather, and nearly impossible to start in cold weather. The electric starting systems that were just coming into use on farm tractors would not have the necessary power to crank a diesel engine in most conditions, and hand starting one was out of the question.

In the late 1920's, IHC and Caterpillar were both beginning research on diesel engines. Caterpillar got a tractor to the market first, with the Caterpillar "Diesel" tractor tested at Nebraska in mid-1932. Caterpillar had solved the starting problem with a "pony" motor mounted alongside the diesel engine. This system allowed the diesel to be started directly, and the heat from the pony engine was used to preheat the combustion chambers and water jackets of the diesel engine, which made starting easier. The Caterpillar "Diesel" produced a maximum 77.08 horsepower from 1090 cubic inches of displacement.

In late 1934, IHC got into the diesel game with the T-40 diesel crawler, followed by the WD-40 standard wheel tractor in 1935. IHC elected to use a different starting system than Caterpillar. The IHC system used a compression release that allowed the engine to be started on gasoline, using a conventional carburetor and magneto, and then be switched to diesel operation after the motor had completed 900 revolutions. This system had some advantages, as it allowed the engine to be hand cranked. Even in the short time that had elapsed between the first cat diesel and the WD-40, diesel technology had advanced considerably, with the WD-40 developing 48.79 horsepower from only 460 cubic inches of displacement.

During this period, Deere had been busily developing the Models A and B and the variations of these basic designs, which enabled Deere to get rid of the less-than-successful GP tractors. Deere's big tractor, the model D, had also been substantially redesigned during these years. Since Deere was not in the industrial business in any big way, the development of the Caterpillar diesel was of little concern, but the introduction of IHC's WD-40 got Deere's attention, as this tractor was a direct competitor to the model D. Subsequently, in the early fall of 1935, Deere engineers began to investigate the problems of a diesel engine for a future John Deere tractor. At first thought, the diesel would seem to be an ideal engine for Deere, as the large displacement, slow turning, horizontal two cylinder engines used by Deere would seemingly lend themselves to diesel service. Rather than build a complete tractor, the Deere engineers elected to build two power units to investigate the possibilities of a diesel engine for John Deere tractors.

Early investigations concerned the problems of starting a diesel engine in cold weather. All Deere tractors to this point used a simple method of starting, merely turning the flywheel. Obviously, this method could not be used with a diesel engine, as the 16:1 compression ratio needed for successful diesel operation required something in the neighborhood of ten horsepower just to turn the engine over against full compression. Very little is known about these first attempts, but it is known that one of the power units had a start-on-gas, run-on-diesel system similar to the IHC system, and the other used some sort of system promoted by a Mr. Hellemn, who had worked out a starting system for diesel engines in automotive use. Neither of these systems were deemed satisfactory. Both of the engines were used to explore different types of combustion chambers and piston con-figurations, as the science of combustion chamber technology was still in its infancy.

In 1937, both of the previous starting systems were abandoned, and a 24-volt electrical starting system was tried, but was found to be unsatisfactory for a number of reasons. Cold weather operation proved to be difficult if not impossible, due to the need to preheat the engine and combustion chamber. This system was heavy, bulky, and expensive, and could not crank the diesel engine for extended periods of time.

At some point in 1938, apparently two diesel tractors were built. Information on these tractors is nearly non-existent, but it is safe to assume that these were probably modified model D tractors with diesel engines. Again, nothing is certain, but the early power unit experiments were probably based on a "W" engine, so these components would have fit in a D. Evidently, these experiments showed promise, as on June 30, 1939, the first "MX" tractor was built, MX 136. The MX designation would be used to identify the experimental tractors that would be used to develop what eventually became the R diesel tractor. MX 136 was scrapped on December 20, 1942.

Due to the two cylinder horizontal engine configuration that Deere was committed to, purchasing a diesel engine from an outside source, as some other manufacturers were doing, was out of the question. Development of a diesel engine of necessity had to be an in-house project. There has been some speculation that perhaps Deere had some "help" in their diesel project from Caterpillar, which at that time probably produced the finest diesel engines in existence. There is no known written evidence to support this theory, but a certain amount of circumstantial evidence exists. It is known that Jesse Lindeman, who was certainly well known to Deere engineering at this time, had a sort of working relationship with some people at Caterpillar engineering, and one can speculate on how that relationship was established. At about the same time that Deere engineering began work on the diesel project, Deere and Caterpillar entered a joint marketing agreement. Deere would supply Caterpillar dealers with wheel tractors, and Deere dealers would have the option of selling the Caterpillar line of crawlers and industrial equipment, which gave Caterpillar and Deere a broader range in which to market their products. In return, Caterpillar had virtually given Deere what remained of its combine business, in which it was no longer interested. In view of these marketing agreements, it is reasonable to speculate that perhaps some small exchange of technology occurred from time to time, as Deere had expertise in fields that Caterpillar did not, such as hydraulics. It is also interesting to note that the engine design finally used in the R tractor shared the same bore, stroke, and intake valve dimensions as a D-8 Cat. whether this was coincidence is a matter of opinion. Certainly Deere could have purchased a D-8 and probed its secrets as it saw fit. In any case, in all probability, nobody will ever know for sure.

Regardless of who may have helped or copied whom, diesel engine development was sufficiently advanced by early 1940 that the Engineering Department issued Engineering Order #8059, which called for the design of a completely new tractor incorporating the diesel engine. This tractor would be a larger, more powerful, and more versatile tractor than the model D, then Deere's most powerful tractor. The D had been developed to the point that any substantial increase in horsepower would have required extensive redesign anyway, so at this point Deere realized that a completely new tractor was needed. In 1941, eight prototype tractors were built, and immediately subjected to exhaustive field tests. These tractors were given the MX designation, and all subsequent diesel prototypes leading up to the R would be known as such.

The 1941 MX tractors bore little resemblance to any John Deere tractor, looking somewhat like an LA Case. More than likely, the rounded sheet metal served to camouflage the tractor, and to allow Henry Dreyfuss and Associates to try out new styling ideas for the future. The 1941 MXs were equipped with a starting engine built by the Moline Tractor Works. Very little is known about the mechanical features of these tractors, other than what can be deduced from the few pictures that survive. These tractors developed some weaknesses and field problems, so in 1944, five more MX tractors were built, incorporating improvements to overcome the deficiencies encountered in the 1941 tractors. The 1944 tractors also incorporated a new styling scheme, beginning to look more like the R that they would eventually become. These tractors had a very high hoodline, perhaps necessary to accommodate what appears to be a starting engine with a vertical configuration. These tractors were reported to have given relatively good field performance, but still fell short of the performance and reliability goals that the engineers had set.

In 1947, the failures and successes of both the 1941 and 1944 MX tractors were evaluated, and eight more MX tractors incorporating the necessary improvements were designed and built. These tractors very much resembled the production R tractors. These 1947 MX tractors were equipped with an opposed two cylinder starting engine, which enabled the hoodline to be lowered. The styling incorporated in this series of MX tractors would change little in the production tractors to come, and would set the style for all new John Deere tractors to come for nearly the next decade. These tractors were sent out to many different areas of the U.S. and Canada, with one unit logging over 4000 hours in Argentina. These tractors were apparently quite successful, as by August, 1947, the final changes were specified to this design. From this point on, the tractor would be known as the model R.

The new model R was introduced to the dealers beginning with a sales meeting held at Winnipeg, Manitoba, Canada, in June of 1948, with other sales meetings to follow. Apparently, a few pre-production R tractors had been built by this time, as many of these sales meetings were accompanied by field demonstrations. Serial production was still six months away, but Deere wanted to make sure that the sales force knew all about the new tractor. Field experience with the new tractor convinced many a dealer that the new R was a winner, with more power than the D, and fuel economy almost too good to be believed. The R would pull one more bottom than a D in nearly all conditions, and was certainly the equal and in most cases the superior of what was thought to be its primary competitor, the IHC WD-9.

The new R used an engine with bore and stroke dimensions of 5.75 by 8 inches, respectively, with a displacement of 416 cubic inches. An opposed two cylinder starting engine with 23 cubic inches and an estimated ten horsepower at a speed of 4000 rpm was used to start the diesel engine. The use of the starting engine instead of other types of starting systems had several advantages. Since the cooling system of the starting engine and the diesel engine were shared, heat from the starting engine served to warm up the diesel. Exhaust heat served to pre-warm the incoming intake air, which also helped to promote easier and faster starting. Finally, the starting engine could be used to crank the diesel as long as necessary, which was not possible with electric systems. The starting engine on the R was built at a very high quality level, due to the hard service and abuse these engines received. The starting engine was equipped with magneto ignition and electric starter, with a hand starting backup system available in case of starter or battery failure. Starting was a very simple procedure. Once the starting engine had been started and allowed to warm up a few moments, the operator s-l-o-w-l-y pulled the lever which engaged the diesel engine, along with the decompression lever. The diesel engine was allowed to turn for a few moments, then the decompression lever was released, allowing the diesel to "motor" for a few revolutions, and then the throttle lever was advanced, and the engine would start. Obviously, in cold weather this procedure took a little longer, perhaps requiring ten minutes of pre-warming and cranking to enable the diesel to start.

Once started, the operator took control of the most massive tractor built by Deere to that point. Almost every part of the R was ruggedly built, almost to a fault. The crankshaft alone weighed 216 pounds, the final drive gears 107 pounds each, with other parts in proportion. The engineers who designed the R were evidently of the "when in doubt, go stout" persuasion. The R pioneered several "firsts" for John Deere tractors. Of course they were the first John Deere diesel, but they were also the first Deere tractor to have "live" PTO, and had a form of live hydraulics. Since the PTO drove the hydraulic pump, the hydraulics were "live" as long as the PTO was running. Hydraulics and PTO were controlled by a separate clutch. The advantage of this system was that when not needed, both systems could be turned off, saving wear and tear, and freeing up a little horsepower, as well. The disadvantage was that to have hydraulics, the PTO had to run constantly, and the PTO drive gears were perhaps the only parts of the R that had an inherent weakness. The bevel gears that ran the PTO were not nearly as stout as they should have been, and replacement of these gears required the removal of all the transmission gears and shafts just to get to these gears. Not a fun job to replace, for sure.

The other "first" was an all-steel cab, offered as optional equipment. Rumor has it that when Deere decided to offer a cab, the first prototypes were made from fiberglass. Fiberglass was a fairly new science in the late 1940's, and there were a few things to be learned. According to the story, these fiberglass prototypes were all right in moderate temperatures, but would shatter in extreme cold, and warp severely in high temperatures and/or humidity, so an all steel design was adopted. These cabs were a long way from a Sound-Guard, but they sure beat sitting out in the Breeze, on a cold, windy day on the High Plains.

The first production R tractor, serial number 1000, is listed as being shipped 1/12/49, its destination, the Experimental Department. This tractor was picked up at the factory by the purchaser, Louis Toavs, of Wolf Point, Montana, on 3/01/49. Mr. Toavs owns this tractor today, having traded it in 1955 for a new 80, and then reacquiring the tractor in 1980. It resides today in his vast collection of John Deere tractors.

R number 1358 was built 4/01/ 49, shipped to the Engineering Department, and then shipped to Lincoln, Nebraska for tests. Don't assume that because this tractor went to Engineering first that it was modified in any way. This was standard procedure for Deere, and probably most other manufacturers. A tractor sent to Engineering for the purpose of being the Nebraska test tractor was merely checked over to make sure that the tractor met specifications, and perhaps received a brief run-in, just to make sure. Nebraska inspectors were, and are, notably intolerant of visible modifications or a tractor believed to have been "doctored".

From April 19 to April 28, 1949, number 1358 was put through its paces at Nebraska. When the tests were completed, the R had shattered the fuel economy record, then held by a Caterpillar tractor. The R proved itself the most powerful Deere tractor yet built, with a corrected maximum of 5O.96 hp at the belt and 45.69 at the drawbar, surpassing the IHC WD-9 by several horsepower, with 28% better fuel economy than the WD-9. Number 1358 was returned to Waterloo, and was kept in inventory for several years. The final fate of this tractor is unknown at this time.

Model R's could be equipped with a wide variety of tire and wheel options to suit nearly every farming need. Regular wheel equipment consisted of 7.50-184 ply front tires and 14-34(16.9-34) rear tires on 12" rims. This wheel and tire combination could also be obtained with 14" rear rims.

Optional tire equipment included 15-34 (18.4-34) in either regular or rice and cane style tread. Tractors ordered with rice and cane tires came equipped with 7.50-18 single rib front tires and mud shields for the rear axle and brakes. Steel wheels could also be furnished for customers in extremely rough conditions or bottomless rice field conditions. Steel wheeled tractors destined for rice field use were also equipped with mud shields. Fifth gear was blocked out in tractors equipped with steel wheels.

PTO and hydraulics were optional equipment. PTO could be ordered alone, but customers who wanted hydraulics were obliged to order PTO as well, as explained earlier. A radiator shutter, hour meter, and wheel weights completed the options list. There is a further option noted in very late R price lists, the AR 970 R (factory code) Special Heavy Load Transmission, with reduced 3rd, 4th, and 5th speed gears. This transmission offered speeds of 2.25, 3.5, 4.0, 4.5, and 5.5 mph. Deere had begun to see the industrial potential of the R, so perhaps this option was directed at industrial customers. Whether any tractors were built with this transmission is a matter of conjecture, as the R parts book and service manual give no reference to this transmission whatsoever.

The new model R sold well from the first, as farmers in the wheat and small grain growing regions of the High Plains and prairies of U.S. and Canada were hungry for more power than the Ds they were used to. Once the message of the power, outstanding fuel economy, comfort, and versatility of the new R’s spread, sales were excellent, reaching a maximum of 5800 tractors in 1953. Sales of the D plummeted, and the last Ds would be built in mid-1953. Export sales of the R were especially good, with 3570 R’s exported. Export locations are not listed in the records, so where the exported R’s were shipped is unknown. However, a note in the serial number register reveals that three R’s, numbers 3970, 3972, and 5005, were recalled from the Kansas City branch and were then shipped to Cuba.

Even as the R’s approached the peak of their popularity and sales, the Minneapolis branch was doing research on the power needs of the wheat farmer in its sales region. A report issued to the factory in late 1951 stated in no uncertain terms that while the R was currently doing the job, the newly introduced Massey 55 diesel, the revised WD-9, and the Oliver 99, all had more horsepower than the R. Minneapolis suspected that many IH dealers were "turning up" the WD-9s to surpass the R, and recommended that the horsepower of the R be increased to better compete with these models. Minneapolis wanted a tractor with 75 horsepower, as it was felt that farmers in this territory could profitably use this much horsepower. As the sales leader for wheatland tractors, the input from the Minneapolis branch was certainly taken note of' but the Waterloo engineering group had its hands full, as at this time the final preparations were being made for the introduction of the 50 and 60 tractors, the model 70 was being developed, with a diesel version slated for a 1954 introduction, as well as future LP-gas version of these tractors. The R, whether Minneapolis thought it was under powered or not, would have to carry the load, which it did, selling well until the end of production in late 1954. The lugging power inherent in the two cylinder engine, the reliability and simplicity of its design, and the unsurpassed fuel economy kept the R competitive until the end. Truth be told, once the mechanics had gained some experience with them, more than a few R’s were "turned up" to satisfy owners who hungered for more power. Due to the excellent design, a "turned up" R would withstand the added stresses very well, although due to the lack of a water pump, engine temperature had to be closely watched. Today, R’s modified for tractor pulling, with owners claiming outputs of over 100 horsepower, have little or no trouble with the transmission of final drives, proof that the R was built to take it.

A number of model R tractors were retained by the factory for tests of one kind or another, and some of these tractors were retained in inventory for some years after production had ceased. One of these tractors, number 7093, was built 2/06/51, and was used for tests. This tractor remained in inventory until 3/05/58, when it was shipped to Earle, Arkansas, to be sold as a used tractor. This tractor was evidently the last R to leave the factory. Other R’s were used for various tests, notably number 10859 and 10860. These tractors were shipped to the Experimental Department and remained there for two weeks, where tests were conducted to determine the suitability of the R for industrial service. Don Merrihew of Mt. Pleasant, Michigan owns number 10859, and this tractor shows evidence that a number of different mounting points were tried for various items of industrial equipment. This tractor appears to have been painted industrial yellow from the factory. Once the factory tests were completed, these two tractors were shipped to Little Rock, Arkansas, and it is believed that they spent some time at the Deere experimental farm in Arkansas.

The last R produced for the U.S or Canada was number 22081, built 8/ 26/54 and shipped 10/22/54 to Memphis, Tennessee. Additional export orders were filled with numbers 22082-22293. Number 22293 was built 9/17/54, and shipped export on 10/17/54. Evidently, some new Rs remained in inventory, as number 21938, 21879, 21869, 21866, and 21863 were not shipped until 4/01/55, the last NEW R’s to leave the factory.

In recent years, the R has seemingly been ignored by restorers and collectors, in favor of the later 80, 820, and 830 tractors, but this is beginning to change, as people begin to realize the significance of the R. Yes, there were a lot of them built, and due to the excellent design, the survival rate of the R’s is quite high, so there are a lot of them still out there, waiting for a new home. The R is the most simple of the two cylinder diesel tractors to restore, and since they were built at very high quality levels, many R’s will need nothing more than a good tune up and cosmetic restoration. The opposed two cylinder starting engine of the R was far more robustly built than the V-4 starting engines of the later diesel tractors, and gave very few problems.

A word about paint and decals. Since the color scheme was green with yellow wheels for most of the R’s, paint isn't much of a problem. It is possible that a few R’s built for industrial concerns or road departments were painted industrial yellow or highway orange, but the records do not reveal this information. Decals, as always, should come from the reputable after market suppliers, as the generic decal sets sold by the local tractor supply are sometimes grossly incorrect, and usually do not have instructions for proper placement. The best costs very little more, and will add to the enjoyment and value of your tractor.

Over 17,000 Rs were shipped to the U.S and Canada, so there are a bunch of them still out there. The vast majority were shipped to the High Plains regions and prairies of the U.S. and Canada, though some were shipped elsewhere, and one could turn up anywhere. The tractors equipped for rice field operations will be found in the rice growing areas of Arkansas, Louisiana, and Texas. An R equipped with the large rice and cane tires or full steel is an impressive tractor.

The R was the first John Deere diesel, representing over twelve years of research and experimentation, and they were the last of the letter series tractors built. Obviously, for reasons of room or pocketbook, an R isn't for everybody. However, in the opinion of this writer, you haven't really lived until you have heard or seen an R in full cry, either a stocker pulling the heavy tillage implements it was designed for, or a modified R pulling a sled, using all of its power and traction. The heavenly host itself could make music no finer.