CaterpillarĀ® History

The name "Caterpillar" brings to mind machines that are made mobile using revolving, oblong tracks, instead of wheels - often referred to as "crawler tractors." What follows is a brief history of the "Caterpillar" tractor and the companies that made it.

The "crawler" type of machine was developed for use on soft ground. The weight of the "crawler" machine is distributed over a much larger surface area of tracks - allowing the machine to traverse soft strata. A wheeled machine has very limited surface area over which to distribute its weight. In addition, farmers and ranchers in the American West found that the "crawler" tractor had better traction with the ground than wheeled tractors, and could pull more weight for a given horsepower. And the "crawler" tractor was far more stable on uneven or hilly ground, where farmers and ranchers grew wheat and other agricultural products.

The earliest documented creation of a "crawler" machine was in a patent awarded by the government of Great Britain in 1825 - the tracks replacing wheels on each side of a cart used on soft soils. A few years later, another Englishman used the ideas found in the first patent and applied "crawler" tracks to a thirty-ton steam tractor, but the experiment was a failure. In 1858, in California, another steam-powered crawler tractor was built and displayed at the State Fair, where it received an award. The inventor was also awarded a U.S. patent, but the inventor lacked financial resources to make the invention a success.

The next documented creation of a "crawler" machine was in the United States, when, in 1900, Alvin O. Lombard started building "crawler" tractors powered by steam boilers. Lombard's tractors were created to haul timber in the woods of Maine. In those days, logging operations were conducted in the winter, because it took fewer horses (less energy) to pull logs loaded on large snow sleds. The sleds were pulled on roads built of snow. The tracks where the sled runners traveled on the snow roads were finished with a topping of ice to reduce the friction or resistance between the heavy sled runners and the snow-road under them. Using sleds and iced snow roads allowed horses to pull much more weight than they could otherwise pull using wheeled trailers on dirt roads. Lombard sought to replace horses with steam power, increasing the amount of work that could be done and reducing the cost of accomplishing the work. The steam-powered crawler tractors could pull behind them many sleds filled with logs, reducing the cost of transportation. As the tractors were very heavy, crawler tracks were used to spread the weight of the steam tractor over a large surface, helping to reduce the adverse impact of the machine on the (relatively) soft snow roads.

Other places had similar problems with soft ground. One of those areas was the one-half million acre delta of the San Joaquin and Sacramento Rivers south of Stockton, California. The land was very rich in nutrients, but very soft - almost too soft for horses, and certainly too soft to support heavy agricultural equipment on wheels. A manufacturer of agricultural machines, including large "combined harvesters" (harvesters that cut the grain, separated the grain from the chaff, discarded the chaff, threshed the grain to remove the outer hard shell, and poured the threshed gain into bags) and steam tractors, lived in this area. He was keenly aware of the need for equipment that could harvest the grains grown on the delta. His name was Benjamin Holt, and he was the president of a family-owned firm, The Holt Manufacturing Company of Stockton, California. Benjamin Holt owned a farm on similarly soft soils. At the time, steam tractors were widely used in the area for agricultural harvesting. In order to overcome the weight distribution problem on soft soils, the iron wheels on the tractors were extended in width horizontal to the ground, making for very wide tractors of nearly 50 feet. The wider the wheels, the less maneuverable the tractor became.


Before the introduction of steam tractors, horses or mules were used to pull the harvesters through the fields of grain. But with the development of "combined" harvesters, the machines were becoming bigger and heavier - attributable to the increased number of functions the machines performed. Accordingly, teams of horses had to struggle to pull the agricultural implements, and it became increasingly necessary to utilize steam tractors to pull the combined harvesters.

Holt was an inventor and manufacturer. His family's firm specialized in manufacturing combined harvesters. Their first was sold in 1886 and their first steam traction engine was sold in 1890. His combined harvesters used chains and sprockets to transfer power from the steam engine to the moving parts of the harvester. Chains and sprockets were the fundamentals of a working "crawler".

Holt was already aware of the notion of "crawler" tractors powered by steam. Holt saw one of Lombard's machines, and several other tracked machines around the US and Europe, and was inspired to create a similar machine at his manufacturing works. Holt's version was first tested on Thanksgiving Day in 1904. Company engineers were instructed to remove the rear wheels off of a steam-powered steam traction engine and replace them with the tracks Holt had designed. This track-type tractor prototype underwent additional tests in March 1905. The story is that during the additional tests, Holt's photographer, Charlie Clements, saw the motion of the track undulating between the drive sprocket and the front idler wheel, and exclaimed that the machine crawled like a "caterpillar." Holt adopted that name for his "crawler" tractors.

Between Thanksgiving 1904 and the end of 1906, Holt had fabricated six steam-powered track-type tractor prototypes. The third prototype tractor actually became the first production machine when it was sold to a company in Louisiana that was reclaiming wetlands that would be dedicated to growing sugar cane.

The steam boilers on all tractors, wheeled or "crawler", proved problematic. As they worked in the fields, they spewed hot cinders that often started fires, especially on grasslands - the wheat and hay fields being harvested as they became golden yellow and dry. The steam boilers were also subject to explosions when steam pressure was inadvertently allowed to become too high or water levels in the boilers to become too low. Even today, antique steam tractor enthusiasts are familiar with the tragedies of antique steam tractors on display at fairs and shows exploding and injuring or killing those nearby.

Aware of the limitations of steam power, in early October 1906, the Holts organized the Aurora Engine Company in Stockton, California, and commenced experimenting with gasoline-fired internal combustion engines - a relatively new arrival on the scene and used to power the new-fangled "horseless carriage" or "automobile". In 1908, production of gasoline-powered "Caterpillar" tractors began, with four produced in that year. The gasoline engines had about 40 horsepower and were styled a "Holt Model 40 Caterpillar." A year later, the same tractor, with a slightly larger engine, was manufactured and labeled the "Holt Model 45 Caterpillar."

The designations of model numbers in the early days (1900-1925) were based upon either horsepower (e.g., the Holt "60") or weight of the tractor (e.g., the "Holt 10-Ton"). Best, one of Holt's competitors that we will learn more about shortly, designated his models by horsepower; Holt initially by horsepower, and later by weight.


Daniel Best was a competitor of the Holt concern. Best had established small factories in Oakland, California, and Albany, Oregon, by 1879 where he manufactured grain cleaners and separators. In 1885, Best had built and sold his first combined harvester. Because of his expanding product line and limited space at his factories, he purchased the existing plant and property of the San Leandro Plow Company in San Leandro, California. Setting up a new company, the Daniel Best Agricultural Works, Best relocated all of his production there in late 1886 and closed the Albany and Oakland plants.

Best bought the rights to another inventor's steam-powered tractor, and began production of steam traction engines in 1889. Early recognition of the limitations of steam power led Daniel Best to tinker with gasoline-fired internal combustion engines around 1890. In 1893, Daniel Best renamed his company and incorporated it as the Best Manufacturing Company, and in that year produced his first gasoline-powered tractor. But for a period of years thereafter, gasoline tractors were still experimental, and production of the factory consisted largely in steam tractors and in combined harvesters.

Daniel Best was a prolific inventor and had a number of patents to his name. Competition between Best and Holt led to a patent infringement lawsuit commenced in 1905. By the time the trial and appeal had been finished, and with the prospect of a re-trial, the parties decided to settle the matter. Accordingly, in 1908, Daniel Best, retiring from business, gave one-third of the Best Manufacturing Company to his son, Clarence Leo ("C.L.") Best, and sold a two-thirds interest in the Best Company to Benjamin Holt. Even though C.L. Best became president of the new Best concern, Holt had effective control.

In March 1909, the Holt concern, seeking to expand its markets in the mid-West, established a subsidiary manufacturing plant in Minneapolis, Minnesota, under the name Northern Holt Company. Benjamin Holt's nephew, Pliny E. Holt, had been dispatched to Minneapolis to superintend that manufacturing plant. There, Holt started manufacturing "Caterpillar" tractors. In late 1909, Pliny Holt purchased the manufacturing facility of a bankrupt firm located in East Peoria, Illinois. Another Holt subsidiary, Holt Caterpillar Company, was incorporated on January 12, 1910, and the manufacture of the Holt Model 45 "Caterpillar" tractors was continued at East Peoria, beginning in February, under Pliny Holt's supervision.

In 1910, C.L. Best left the Holt-controlled Best Manufacturing Company, and started the C.L. Best Gas Traction Co. in Elmhurst, near San Leandro, California. Holt sued, claiming breach of contract and infringement on the "Best" name (Holt owned the Best Manufacturing Company), but Holt lost. In 1912, C.L. started producing his first "crawler" tractor, a 70 horsepower model. Since in 1910 Holt had registered the name "Caterpillar" as a trademark with the U.S. Patent and Trademark Office, C.L. styled his "crawler" tractors "Tracklayers". Then, in 1915, C.L. demonstrated one of his new "Tracklayer" tractors at the state fair, and Holt sued again, this time for patent infringement. After the commencement of this second lawsuit, C.L. bought the Lombard patents (that pre-dated Holt's "crawler" patents) for $20,000, and then countersued Holt for patent infringement. The upshot of the court actions was that the parties settled, with a cash payment to C.L. Best plus a license authorizing C.L. Best to use all the Holt patents in the manufacture of the C.L. Best "Tracklayers."


The two companies continued in stiff competition. In 1911, The Holt Manufacturing Company introduced its "Holt Model 60 Caterpillar", built at its Stockton, California factory, and in the same year, began production of its "Holt Model 40-60 Caterpillar" at its East Peoria, Illinois plant. The basic difference between the two versions of the Holt Model 60 was in the head and valve design of the engines. The Model 60 (and 40-60) was a highly popular product, soon outselling the earlier Model 45.

In 1912, Holt introduced its "Holt Baby 30 Caterpillar", and in 1914, introduced the "Holt Model 18 Midget Caterpillar", both designed for orchard and vineyard work, and both built at Holt's Stockton, California factory. Three hundred forty-seven "Midgets" were manufactured before production ended in 1917.

In 1913, Holt introduced its hugely popular "Holt Model 60-75 Caterpillar", manufactured at its Stockton plant. By 1916, this machine became the "Holt Model 75 Caterpillar", the best-selling front tiller-wheeled tractor the company ever produced. Starting in 1916, it was built at both Holt plants. The only differences between the Seventy-Fives produced at Stockton and those produced at East Peoria were in the engine cooling systems and in the track assemblies. The "Holt Model 75 Caterpillar" was produced into 1924.

In 1914, the same year as the "Midget" was introduced to farmers, Holt introduced the "Holt Model 120 Caterpillar", essentially designed for military use to pull heavy artillery pieces on battle grounds. Most of these tractors were destined for the battle fields of France in World War I; all were built in East Peoria, and surprisingly, production continued to 1922.

Also in 1914, Holt redesigned its "Holt Model 45 Caterpillar" to run without a front tiller-wheel, the first "crawler" tractor to do so. It was found that by disengaging the power to the tracks on either side, the machine could be turned without a wheel in the front of the tractor to effect the change in direction.

In mid-1913, Holt dissolved all of its subsidiaries and consolidated most of their operations under The Holt Manufacturing Company. This included the Aurora Engine Company and the Holt Caterpillar Company. However, the Best Manufacturing Company was shut down completely, leaving the plant in San Leandro idle.

In 1917, Holt introduced its "Holt 5-Ton Caterpillar" model, primarily designed for military hauling duties. As Holt did not have the production capacity to meet the military's requirements for World War I, the company licensed two automobile manufacturers to supply the military's needs for that tractor: the Maxwell Motor Car Company of Detroit, Michigan, and the Reo Motor Car Company of Lansing, Michigan. This model was converted into a commercial model in 1918 and was produced by Holt up to the merger of the Holt company into the Caterpillar Tractor Co. that would occur in May of 1925.

In 1917, Holt also introduced its "Holt 10-Ton Caterpillar" model, again, primarily designed for military hauling duties. This model was converted into a commercial model two years later and was produced by Holt up to the time of the merger.


C.L. Best was known for continual changes and improvements to his products, and, at least in the West, the Best "Tracklayer's" reputation soared. He had been using Buffalo-brand gasoline engines in his tractors, but, in 1913, Best started the manufacture of his own four-cylinder gasoline engines, and installed them in his tractors. Best's first "crawler" tractor was its C.L. Best Model 70 "Tracklayer". The "70" had some desirable features missing in Holt's products: a liberal use of high-grade steels (instead of iron), and power-assisted steering for the front tiller wheel. In 1914, Best's Model "70" became the C.L. Best Model 75 "Tracklayer", with the added power indicated by the model number. The Best Model 75 was produced through 1919.

In 1914, Best introduced its "humpback" Model 30 "Tracklayer". It was called a "humpback" because the sprockets that turned the tracks was not in contact with the ground, but rather was above the back idlers, similar to a modern Caterpillar tractor. This tractor was Best's answer to Holt's Model 18 "Midget". The Best "humpback" 30 was discontinued within a year of its introduction.

In 1914, to counter Holt's new "Caterpillar 45" without a "tiller" wheel, Best introduced his C.L. Best Model 40 "Tracklayer", also the first Best tractor without a "tiller" wheel. Since the Best Model 40 was lighter in weight, the 5 horsepower difference was unimportant. Best discontinued this model in 1919.

In 1916, Best introduced its C.L. Best Model 90 "Tracklayer" and its Model 120 "Tracklayer", both models very large tractors, and its much smaller tractor for agricultural uses, the C.L. Best Model "8-16 Tracklayer," introduced in 1915. All three tractors were discontinued in late 1917. Best released a memorandum stating, "Owing to the demand for the '40' and '75' Tracklayers we have discontinued construction of all other models."

In 1916, with a financial enticement from the city of San Leandro, C.L. Best purchased Holt's recently-vacated production plant in San Leandro, and moved his manufacturing from Elmhurst back to his father's old factory in San Leandro. Additional financing was arranged, and the old buildings were replaced by a modern factory facility.

In 1918, Best introduced its smallest tractor, the C.L. Best Model 25 "Tracklayer", of which about 300 were manufactured before production was discontinued in 1919.

In 1919, Best introduced its "Best 60 Tracklayer", the first big Best tractor without a front "tiller" wheel for steering. It was to become the best-known of all of C.L. Best's tractors, and was the finest large tractor then made. This was followed by the 1921 introduction of the Best 30 "Tracklayer", built on the same principles as the popular 60, but about one-half the size and with one-half the power. As with the Best 60, the Best 30 met huge approval in the marketplace.


World War I brought additional business to Holt. The Holt company had previously expanded its markets overseas, including Russia, Europe, and South America. Therefore, his machines were known overseas. He also had experience with securing government contracts. His overseas markets and acumen with selling to governments separated him from the competition. He was able to sell most of his production of tractors to the U.S. military, which tractors were used to pull artillery pieces and wagon-loads of supplies "Over There". Also, several other concerns were licensed to manufacture "Caterpillar" tractors to Holt's specifications to meet the Army's demand. He sold to the U.S. Army the following tractors: 1,800 of the Holt Model 45 "Caterpillars"; 1,500 of the Holt Model 75 "Caterpillars", and 90 of the Holt Model 120 "Caterpillars". Holt's total war production of tractors has been estimated to have been over 5,000, with 2,100 of them having been sold to the Allies. He also sold his newer 5-Ton and 10-Ton models with armor panels on them. The company prospered.

Despite Holt's war-time sales success, the company was left in a weakened position at the close of the War. The military had contracted with Holt for the production of a total of 24,791 tractors, but by the end of the War on November 11, 1918, only 9,771 tractors had been manufactured under the contracts. The company had undertaken an expansion in plant capacity based upon the nearly 25,000 tractors requested, and the need for that capacity ended abruptly, as the procurement contracts with the military were cancelled. Additionally, the tractors so favored by the military - large and heavy machines - were ill-suited to the needs of farmers, Holt's biggest customers before the War. Moreover, Holt had a large inventory of tractors destined for the military, but with the cancellation of the procurement contracts, Holt was left without buyers for them. Additionally, surviving U.S. Army Holt "Caterpillar" tractors from Europe were brought back to the U.S., and together with those that had been stockpiled here awaiting shipment, were sold as War surplus - depressing the new tractor market for years. Those armored War surplus tractors could be seen working on farms, for municipalities, and on construction and logging jobs for some years after the War.

At his death in 1920, Benjamin Holt's company was in difficult financial straights. In order to keep the company going, money was borrowed, and that gave the bankers a large say in the affairs of the company. The banker with the most clout was Thomas Baxter, who threatened to ruin the company unless he was made its president. The company had little choice if it wished to survive, and so Baxter succeeded founder Benjamin Holt as president. Baxter realized that the company's customers needed smaller "crawlers", and eliminated the largest tractors from the line-up.

President Baxter decreed that, with the U.S. government announcing a highway building fund, Holt would gear a significant part of its business toward road construction, so as to garner a slice of those funds. But developing a new product line emphasizing the smaller tractors that farmers needed cost money, and that increased the already high debt the company was carrying. In order to equip the "Caterpillar" tractors with road-building equipment, such as earth-moving blades ("bulldozers") and pull-scrapers which Holt did not manufacture, the company would eventually turn to independent manufacturers such as Robert G. LeTourneau to supply them.

While failing to obtain a military contract during WWI, Best obtained assurances from the government that he would have all of the steel his company needed to continue manufacturing tractors for farmers during the war. This set the company up for having the market advantage when the war ended. During the post-war depression, the company's sales actually increased by nearly 70 percent. In 1920, the Best company changed its name to the C.L. Best Tractor Co., and assumed a large amount of debt in order to expand production, especially of its new Best Model 60 "Tracklayer". It expanded its product line again in when in 1921 it introduced its popular Model 30 "Tracklayer".


The Best and Holt companies had been engaged in litigation against one another during the period from 1907 to 1918. It has been reliably estimated that the total cost of litigation during that period was roughly $1.5 million, at a time when the dollar had real value. The lawyers and the results of their work had nearly bled the companies dry.

C.L. Best and Benjamin Holt were leaders in their industry. But the fellow who next changed the landscape of "crawler" tractor manufacturing was Harry H. Fair of the bond brokerage house of Pierce, Fair & Company of San Francisco. Fair was the gentleman who had arranged financing for C.L. Best to purchase his father's shops in San Leandro in 1916. Fair was also a significant shareholder in the C.L. Best Tractor Co., and was on its board of directors. Ultimately, Fair was approached by several key Holt shareholders who wished Fair's bond firm to handle future financing of the Holt company. Fair was engaged by the Holt company, and quickly became aware of its precarious financial condition. Fair proposed that the Best and Holt companies consolidate together, as it was possible that they would both go out of business if they did not.

Best had the better financial status, more advanced tractor designs, and the beginnings of a better dealer group. Holt offered its worldwide reputation and name, bigger factories, a 40-year old combined harvester line, and the Caterpillar trademark. The shareholders of both companies accepted the proposal to consolidate together, and in legal maneuvering that occurred in April and May 1925, the Caterpillar Tractor Co.Ā© was formed and the consolidation was effected. The Best factory in San Leandro, California, became the first headquarters location for the new company and limited production was continued at the plant for a number of years. The Holt's factory in East Peoria, Illinois, became the main manufacturing plant for the company. In 1930, the headquarters was officially moved from San Leandro to East Peoria in order to fulfill the terms of the merger.

C.L. Best was named chairman of the board of directors, and Raymond C. Force, Best's attorney, was named president of the company. A consolidation of the companies was intended to lead to more efficiency, a reduction in the combined number of employees, a reduction in models offered, a reduction in plant capacity, and the elimination of duplicate dealerships in the same geographic area, all resulting in what economists refer to as "increasing economies of scale". Indeed, soon after the consolidation in 1925, the product offering of "crawler" tractors was rationalized.

The new company's first product line had only five track-type tractors - the 2-Ton, 5-Ton, and 10-Ton from The Holt Manufacturing Company's former product line and the Thirty and Sixty from the C. L. Best Tractor Co.'s former product line. The 10-Ton and 5-Ton were discontinued in 1926. In 1928, the 2-Ton was discontinued.

Fair's vision was correct, and the shareholders in the consolidated company were rewarded. Between 1926 and 1929, sales more than doubled, and profits roughly tripled. At the same time, the efficiencies of the consolidated operations led to consumer price reductions in the Caterpillar Thirty and Sixty models: from $3,665 to $2,475 for the Caterpillar Thirty, and from $6,060 to $4,300 for the Caterpillar Sixty.


The first tractor that was designed and produced by the Caterpillar Tractor Co. that was not based on a previous Holt or Best model was its Model Twenty, which went into production at San Leandro in 1927. Production of the Twenty was started at East Peoria, Illinois, in 1928.

In 1928, Caterpillar introduced its Model Ten. The Model Ten was designed to replace the 2-Ton. The following year, Caterpillar introduced its Model Fifteen.

The Great Depression is usually thought of as having started in the U.S. with the stock market crash of October 1929. Many would say that the U.S. didn't climb out of the economic depression until the advent of World War II (in 1941 for the U.S.). The decade following 1929 was to prove difficult for all manufacturers, including the Caterpillar Tractor Co.

At the beginning of the Great Depression, Caterpillar had a product line of tractors that included (from smallest to largest), its Ten, Fifteen, Twenty, Thirty, and Sixty. As the Great Depression deepened, Caterpillar adopted the same strategy that surviving automobile manufacturers adopted: introduce new models. Accordingly, in 1931, the company introduced the Twenty-Five and the Fifty. In 1932, the company introduced the "small" Fifteen, the high-clearance Fifteen, and the "small" Twenty. These models were, like all earlier models, powered by gasoline-fired internal combustion engines.

Effective December 7, 1931, all Caterpillar tractors were painted in the now-familiar "Caterpillar Hi-Way Yellow" with black trim, although for an extra charge, any purchaser could have his tractor painted in some other color. Before then, the standard colors used by the Caterpillar Tractor Co. had been gray with red trim.


We digress here to relate how Caterpillar came to introduce the diesel engine to its product line in 1931, which was to revolutionize the Caterpillar tractor. Briefly, in 1893, Rudolph Diesel, a German, received his first German patent on what was to become known as the "Diesel" engine. The essential mechanical difference between a gasoline-fired internal combustion engine and a diesel- (oil-) fired internal combustion engine is that in a gasoline engine, the gasoline vapors inside the cylinders require an electric spark to cause an explosion; in a diesel engine, the compression generated inside the cylinders causes the oil vapor to become hot and explode without an electric spark. The diesel engine requires as little as one-third the amount of the fuel needed by a gasoline engine to produce the same amount of work. Another characteristic of the diesel engine is its "low end torque". The diesel can pull more at low idle and lower engine speeds than a spark- ignited engine. Thus the diesel is noticeably better at "hanging in" as the load increases. For example if you had a tractor with a diesel engine, you could start a heavy load by engaging the clutch without opening the throttle. If you tried the same with a gasoline-fired engine of comparable size, it would be more likely to die. As early as 1898, diesel engines were being manufactured in the U.S. A diesel engine was displayed at the 1915 Panama-Pacific Exposition held in San Francisco, and the display attracted much attention from C.L. Best and his engineer Oscar Starr. However, the diesel engine was not sufficiently developed to be adapted to tractor use, and C.L. Best was not able to use the engine at that time, although he maintained contact with George A. Dow of Alameda, California, a holder of a license to manufacture diesel engines. Dow, through his engineer Art Rosen, subsequently approached the Holt company as early as 1923, suggesting that Holt install diesel engines in the Holt "Caterpillar" line of machinery. However, Holt was not interested in diesel engines. Shortly after the Best-Holt consolidation into the Caterpillar Tractor Co. in 1925, C.L. Best revisited the question of diesel engines. He hired Art Rosen in 1928, who had experience with the application of diesel engines to marine uses. Between 1926 and 1932, Caterpillar spent over $1 million in engineering research and development to produce Caterpillar's first diesel engine - the D9900, for the market.

With Caterpillar's initial diesel engine development was finished, the D9900 Diesel Engine was tested on the Caterpillar Sixty Tractor chassis. As a result, various changes were made to the Sixty, including beefing up the frame of the tractor to carry the heavier diesel engine, and using a different transmission that was heftier and geared down for the diesel engine. The result was a diesel tractor that, in early field tests, worked well under a heavy strain while consuming only 4 gallons of diesel fuel (oil) per hour at a cost of 4 to 7 cents per gallon. (At that time, gasoline sold for 14 to 16 cents per gallon.) The first production models of the Diesel Sixty were sold in 1931 (14 tractors in all), and then the model number was changed to Diesel Sixty-Five, with 142 having been sold in 1932 (totaling 157 tractors in the 2 years of production). The Diesel Sixty-Five production was terminated with the introduction of four new Diesel tractor models in 1933: the Diesel Thirty-Five, the Diesel Fifty, the Diesel Seventy, and the Diesel Seventy-Five, which replaced the Diesel Seventy.

With roughly a thousand diesel-engine tractors in the field, problems with fuels and lubricants became evident. Although the company thought that the diesels would run on any grade of fuel oil, it was found that sulphur and waxes in the fuels were deleterious to the engines. The problems encountered included stuck piston rings, scored cylinder walls, and burned main bearings. It was discovered that oils with paraffin bases instead of asphalt bases did not cause as much sticking of the rings. So the company teamed up with Standard Oil of California to develop the first detergent oils. As it developed, the company could not get the oil industry as a whole to adopt and adequately distribute the detergent oils throughout the U.S., so Caterpillar enlisted its dealership network to distribute the necessary oils until such time as all the oil companies produced and sold detergent oil products manufactured to Caterpillar's specifications.

Once the diesel engine had proven itself reliable and economical, the market for gasoline-powered crawlers declined significantly. The diesel engines delivered more power for far less operating cost than the gasoline engines. For that reason, Caterpillar discontinued a number of gasoline-powered tractor models in the early to mid-1930s.


In the mid-1930s, Caterpillar also was moving toward bigger and bigger diesel-powered tractors. The move to larger tractors was initiated in response to the "New Deal" programs, wherein the U.S. Government was spending huge sums of money on public works projects, as a "pump-priming" measure to increase economic activity to get the country out of the Great Depression (1929-1941). At the same time, manufacturers as Robert G. LeTourneau were building larger and larger implements to accomplish the large and heavy work demanded by the public works projects. Those larger implements required larger and more powerful tractors to pull them. The results of this trend were the introductions of the Diesel Seventy, then the Diesel Seventy-Five, then the RD8, and then the D8, each in its turn the largest and most powerful tractor built.

It was during the Great Depression when the focus of Caterpillar's marketing changed. Small farmers and ranchers did not have the financial resources to purchase Caterpillar products; only the government, and large contractors engaged in public works projects, had a need, and could afford, Caterpillar tractors and other equipment. Accordingly, the company gradually abandoned agriculture as its primary focus.

In order to facilitate brevity, between 1925 and the entry of the U.S. into World War II in 1941, the Caterpillar line-up of tractors, both gasoline and diesel powered, is summarized in the following table. All tractors listed were introduced before 1941, but production on some models lasted into the 1950s. Tractors are listed generally in the order of the year of introduction. Only those manufactured in the U.S. are included.

Model (fuel) Year started Year ended Total number mfg.
Sixty gasoline 1925 1931 16,813 (fn 1)
Thirty gasoline 1925 1932 23,830 (fn 1)
2-Ton gasoline 1925 1928 8,565 (fn 2)
5-Ton gasoline 1925 1926 1,455 (fn 2)
10-Ton gasoline 1925 1925 749 (fn 2)
Twenty gasoline 1927 1932 8,568
Ten (incl. High Crop) gasoline 1928 1933 4,932
Fifteen gasoline 1928 1932 7,559
Twenty-Five gasoline 1931 1933 638
Fifty gasoline 1931 1937 1,808
Fifteen (small) gasoline 1932 1933 307
Fifteen (High Crop) gasoline 1932 1933 95
Twenty (small) gasoline 1932 1933 652
Thirty-Five gasoline 1932 1935 1,730
Sixty-Five gasoline 1932 1933 521
Twenty-Eight gasoline 1933 1935 1,171
Seventy gasoline 1933 1937 266
R2 gasoline 1934 1942 2,418
R3 gasoline 1934 1935 59
R5 gasoline 1934 1940 1,548
Twenty-Two gasoline 1934 1939 15,156
Forty gasoline 1934 1936 584
Thirty (6G)/R4 gasoline 1935 1944 5,383
Diesel Sixty diesel 1931 1931 14
Diesel Sixty-Five diesel 1932 1932 143
Diesel Thirty-Five diesel 1933 1934 1,999
Diesel Fifty diesel 1933 1936 2,065
Diesel Seventy diesel 1933 1933 51
Diesel Seventy-Five diesel 1933 1935 1,078
Diesel Forty diesel 1934 1936 1,971
RD6/D6 diesel 1935 1959 58,973
RD7/D7 diesel 1935 1955 (fn 5) 56,527
RD8/D8 diesel 1935 1955 (fn 6) 46,698
RD4/D4 diesel 1936 1959 (fn 3) 94,496
D2 diesel 1938 1957 (fn 4) 26,454
D5 diesel 1939 1939 46

Footnote No. 1. Estimated. This tractor was produced by the C.L. Best company before the consolidation in 1925, and the exact serial number of the last Best produced at the time of consolidation was not recorded.

Footnote No. 2. Estimated. This tractor was produced by the Holt company before the consolidation in 1925, and the exact serial number of the last Holt produced at the time of consolidation was not recorded.

Footnote No. 3. Through the 6U/7U series

Footnote No. 4. Through the 4U/5U series

Footnote No. 5. Through the 3T, 4T, and 6T series.

Footnote No. 6. Through the 13A series.


Many attachments were added to the tractors in order to make the machines more useful. Early-on, snow plows were affixed to the front of the tractors to open roads in winter. Manufacturers such as LaPlant-Choate affixed earth-moving blades on the front of tractors - the blades commonly referred to as "bulldozers". Other manufacturers, such as Robert G. LeTourneau, manufactured scrapers to pull behind the tractors, for earthmoving purposes. Winches were manufactured by companies such as Carco and Willamette-Ersted to be affixed to the rear of tractors to facilitate the skidding of logs in lumbering operations. And gasoline-fired internal combustion engines were modified to burn butane, a much cheaper form of hydrocarbon fuel than gasoline. Caterpillar Tractor Co. made none of the apparatus for its tractors mentioned in this paragraph.

In road construction and maintenance, the horse-drawn pull-grader was quickly adapted for tractor work. One of the companies manufacturing graders for this purpose was the Russell Grader Manufacturing Company of Minneapolis. In fact, Russell had modified one of its grader products to affix to the front of a Caterpillar 2-Ton Tractor, to create a self-propelled "Motor Patrol". In 1928, Caterpillar purchased the Russell company. The product offerings after Caterpillar's acquisition remained self-propelled graders, tractor-pulled graders, and elevating graders. The so-called "self-propelled" graders at that time were simply attachments to the front of "crawler" tractors. The new self-propelled graders were the Ten Motor Patrol (affixed to a Caterpillar Ten), the Fifteen Motor Patrol (affixed to a Caterpillar Fifteen), the Twenty Motor Patrol (affixed to a Caterpillar Twenty), and the Twenty-Eight Motor Patrol (affixed to a Caterpillar Twenty-Eight).

In April 1931, Caterpillar introduced its all-new "Auto Patrol" rubber-wheeled grader. Late that same year, the Auto Patrol was renamed as the No. 9 Auto Patrol. This machine formed the basis for all motor graders produced by the earth-moving industry.

Model (fuel) Year started Year ended
Auto Patrol gasoline 1931 1931
No. 9 Auto Patrol gasoline 1931 1932
No. 7 Auto Patrol gasoline 1932 1933
No. 11 Auto Patrol gasoline 1932 1940
No. 10 Auto Patrol gasoline 1933 1940
Diesel Auto Patrol diesel 1934 1937
Diesel No. 10 Auto Patrol diesel 1936 1940
Diesel No. 11 Auto Patrol diesel 1937 1940
Diesel No. 12 Auto Patrol diesel 1938 1940
No. 12 Motor Grader diesel 1939 ?
No. 12 Motor Grader gasoline 1939 1942
No. 112 Motor Grader diesel 1939 ?
No. 112 Motor Grader gasoline 1939 1947
No. 212 Motor Grader diesel 1939 ?
No. 212 Motor Grader gasoline 1939 1947
No. 12E Motor Grader diesel 1959 ?
No. 112E Motor Grader diesel 1959 ?
No. 14B Motor Grader diesel 1959 ?
No. 14C Motor Grader diesel 1959 ?
No. 112F Motor Grader diesel 1960 ?
No. 14D Motor Grader diesel 1961 ?
No. 16 Motor Grader diesel 1963 ?
No. 12F Motor Grader diesel 1965 ?
No. 14E Motor Grader diesel 1965 ?


Aside from acquisition of the Russell Grader Manufacturing Company, the Caterpillar Tractor Co. did not build earth-moving equipment, but rather the tractors to which earth-moving equipment was attached. Other companies manufactured earth-moving equipment. Robert G. LeTourneau was an earth-moving contractor, who constantly tinkered with ideas and equipment, and came up with some wonderfully revolutionary ideas in earth-moving. His biggest contributions to the industry were in the line of scrapers, bulldozers, rippers, and the cable control units that operated the adjustments (e.g., raising and lowering blades). LeTourneau was a genius. While scrapers had been around a long time, it was LeTourneau who came up with remote controls for them that allowed the tractor operator to operate them instead of having a second person riding on the scraper where the adjustments were made to the blade. He then developed scrapers with their own motive power, transferring power to the wheels by way of electricity (just as a modern diesel-electric locomotive transfers power to its wheels), and with rubber wheels that could move earth much faster than a "crawler" tractor could pull a scraper. LeTourneau's method of operating was to fabricate the machine, use it on his own jobs, note the flaws, improve it or fabricate a better model, and to again use it on a job. This cycle of creation and destruction resulted in his manufacturing implements that worked.

In 1934, LeTourneau entered into an arrangement with the Caterpillar Tractor Co. as an official implement manufacturer for Caterpillar. LeTourneau would design equipment for Caterpillar tractors, and Caterpillar encouraged its wide network of dealerships to sell LeTourneau's products. Therefore, in 1935, LeTourneau moved his operations from Stockton, California to Peoria, Illinois, where he established a manufacturing plant near Caterpillar's. LeTourneau had placed much trust and confidence in the "crawlers" made by Best, Holt, and then Caterpillar, as those brands of "crawler" tractors were used exclusively by his earth-moving firm. Caterpillar dealers took orders for their tractors to be built with LeTourneau's implements, and when the tractor was finished at the Caterpillar factory in East Peoria, Illinois, it was moved by railcar a short distance to LeTourneau's factory in Peoria, Illinois, to have the implements, such as "bulldozers", installed. In 1937, LeTourneau produced his first scraper without front wheels, a site that is now familiar on all large earth-moving construction jobs.

LeTourneau was not alone in developing and manufacturing implements to be installed on Caterpillar tractors. The LaPlant-Choate firm manufactured hydraulic-controlled "bulldozers" and other equipment for Caterpillar tractors.

Entry of the U.S. into World War II in December 1941 brought challenges to the Caterpillar Tractor Co. During the War, most of the company's production capacity was devoted to military products to meet the government's needs. As with Holt in World War I, Caterpillar licensed American Car and Foundry of Pennsylvania to fabricate Caterpillar's D7 "crawler" tractors to Caterpillar's specifications for the military. Production of the military D7 model was in the neighborhood of 1,100 per month. Caterpillar diesel power units were in large demand by the military for field power. Fortunately for domestic manufacturers, at the close of World War II, the military did not ship the tractors and other construction equipment back from the theaters of war, but left them behind - in the Pacific Theater, often dumped overboard from ships into the ocean. Accordingly, manufacturing of tractors and similar machines was not adversely impacted by "war surplus" equipment, and after the War, Caterpillar shifted its production back to the civilian market.


Caterpillar was moving aggressively into the earth-moving specialty, since that was where the money was to be made. In 1941, it introduced a rubber-tired tractor, the DW10, designed to pull scrapers and other similar implements. The advantage of this tractor over the "crawler" type, was its speed in moving earth. Because of wartime demands, production of the DW10 was suspended in 1943, and would not be manufactured again until 1945. The DW10 pulled one of several implements: the LaPlant-Choate CW-10 Carrymor, the LeTourneau Model LS Carryall scraper, the Athey PD 10 side-dumping trailer, and the Caterpillar W10 bottom-dumping Wagon. The DW10 was built into 1954 when the DW15 was released as its replacement.

The DW10 was intended by Caterpillar to be a direct competitor with LeTourneau's rubber-tired scraper, the "Tournapull", which had been introduced to the market in 1938. Caterpillar viewed LeTourneau's "Tournapull" as a threat to the dominance of Caterpillar's "crawler" tractor in the earth-moving market. Although the two companies worked closely together during the major portion of the War, when their marketing agreement expired in 1944, it was not renewed. This released Caterpillar to manufacture earth-moving equipment that would compete directly with LeTourneau across its product line. And compete Caterpillar did!

In 1945, Caterpillar introduced its first bulldozer straight blades operated by cable control units. Its angle blades were introduced in the following year. They next offered hydraulic controlled blades in 1947.

In 1946, Caterpillar introduced its first pull-scrapers. These were designed to be used with the Caterpillar D6, D7, and D8 tractors, and the scrapers were designated the No. 60, No. 70, and No. 80, and all were operated by cable control units (essentially a winch on the rear of the tractor that controlled cables that controlled the adjustments on the scraper). These were followed by the No. 40 (to be used with a D4 and controlled by hydraulics) in 1949, and a No. 90 first produced in 1951 (cable controlled, to be used with a D8 tractor). Over the next several years, the designs for all of these pull-scrapers were modified with improvements. In 1955, the No. 80 was replaced by the No. 463; in 1956, the No. 70 was replaced with the No. 435; also in 1956, the No. 90 was replaced with the No. 491.

In 1950, Caterpillar began producing its new self-propelled rubber-tired scrapers - the two-axle, four-wheel DW20 and the single axle, two-wheel DW21 - intended to slice into LeTourneau's "Tournapull" market. Again, over the next few years, there were many design changes and improvements to these two models, but in early 1961, both models were discontinued. They were replaced by the 600 series Caterpillar introduced in 1962, with 7 new models. The two-axle models were the 641, 651, and the twin-engine 657. The twin-engine 657 was based upon a similar product manufactured by Euclid that it had introduced in 1949. The three-axle models were the 632, 650, 660, and the 666.


In 1951, Caterpillar acquired the Trackson Company of Milwaukee, Wisconsin. Established in 1922, Trackson had been manufacturing side-boom pipe-laying attachments designed to specifically match Caterpillar tractors since 1936. In 1937, Trackson started supplying its "Traxcavator" cable-operated front-loading shovels for attachment to Caterpillar tractors, and eventually that model line would accommodate the D2, D4, D6, and D7 tractors. After the acquisition of Trackson, Caterpillar eventually made the loaders as a single unit from the ground up, introducing its 933C, 955C, and 977D front-end tracked loaders in 1955. These models continued, with various improvements, into the 1960s. The following table shows Caterpillar's tracked front-end loaders from 1955 to about 1960.

Model Year Introduced
HT4 1950 (ended in 1955)
No. 6 1953 (ended 1955)
933C 1955
933E 1957
933F 1958
955C 1955
955E 1958
955H - PS 1960
955F 1960
977D 1955
977E 1958
977-H - PS 1960

In addition to the tracked front-end loaders, Caterpillar developed rubber-tired wheeled loaders, which were entered the market in 1959, with its Model 944A "Traxcavator". The following year, Caterpillar introduced two more models, the 922A and the 966A. In 1963, two new models were offered, the 988 and the 966B, both of which were articulated steering wheel loaders. These were followed by the 922B (1962), the 950 (1964), the 980 (1966), the 930 and the 992 (both in 1968), and the 920 (1969).

Other Caterpillars with roots in the Trackson Company of Milwaukee were its pipelayers, essentially "crawler" tractors with booms on the side to handle pipe. Caterpillar replaced the concept of a pipelayer attachment on a crawler tractor with the industry's first integrated pipelayer machine, the No. 583 Pipelayer in 1955. The following table shows Caterpillar's pipelayers from 1955 to about 1960.

Model Year Introduced
583C 1955
572C 1957
572D 1958
561B 1959
583H-TC 1959
583-PS 1960

In 1963, Caterpillar entered the off-the-highway truck market, with the production of its 769, a 35-ton capacity truck.

In 1963, Caterpillar also entered the articulated rubber-tired wheeled bulldozer market with the 834 followed by the 824.


In the 1950s, Caterpillar adopted several improvements to its tractors: the wet clutch (improving clutch life), turbochargers (increasing power), and the "powershift" transmission (eliminating the flywheel clutch lever, the gearshift lever, and the forward and reverse levers).

In 1954, Caterpillar introduced its largest tractor to date, the D9D. Entering production in 1955, it was offered in two models - the direct-drive transmission and the torque converter drive. In 1959 the new D9E was introduced, being a more powerful tractor, in three versions - the direct drive, the torque converter drive, and with powershift. In 1961, the D9E was replaced with the D9G, with powershift transmission standard.

In the mid-1960s, in order to meet the needs of the large farms and ranches of the West, especially in the wheat-raising areas, Caterpillar engineered tractors, styling them the "Special Application" tractors - D4, D5, and D6. The "SA" models, engineered for drawbar work (i.e., pulling agricultural implements), offered direct-drive transmissions, variable horsepower in higher gears, full-length fenders to reduce dust reaching the operator from the fast-moving tracks, and more creature comforts.

Here ends our brief history of Caterpillar. The Antique Caterpillar Machinery Owners Club is interested in Caterpillar equipment that is 40 years old, or older. The early to mid-1960s represents the newest equipment of which we take official notice. We hope that you have found this brief history instructive. If you are interested, we have also placed a history of our club on the homepage of our website. Thank you for looking!

For further information, here is a list of books that are currently in print. We encourage you to read them for a fuller appreciation of the history of Caterpillar equipment and the companies involved in manufacturing them.

Caterpillar, by Randy Leffingwell (Osceola, WI: Motorbooks International, 1994), ISBN 0-87938-921-4

Caterpillar Century, by Eric C. Orlemann (St. Paul, MN: Motorbooks International, 2003), ISBN 0-7603-1604-X

Caterpillar's Roots, by Jack Alexander

Additionally, portions of this site may have been reviewed by Caterpillar Inc. Corporate Archives.

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