Engine Development

In March of 1928, C. L. Best met with a young consulting engineer named Carl George Arthur Rosén to discuss the possibility of equipping a Caterpillar 60 Tractor with a diesel engine. Henry Kaiser, who would later found Kaiser Aluminum, had already installed 60 hp Atlas Imperial Diesel Engines in two Caterpillar 60 Tractors, but the Atlas engines had been designed to be stationary engines and were much too heavy for mobile applications. In his yearlong investigation, Rosén purchased engines from several manufacturers both in the United States and Europe, including Benz, Atlas, Buda and Coho. While none of these engines proved satisfactory, his team had gained a great deal of knowledge and was confident that they could design their own diesel that would more closely match Caterpillar's requirements.

The preliminary engineering work was done by January of 1930, the first precombustion chamber test engine was tested on July 3, 1930. A precombustion chamber engine was used because at this time there was no diesel fuel per se. What was available was a collection of various distillates that varied widely in composition and quality. Any engine would have to be able to burn whatever fuel was available locally. Additionally, Rosén's experience with the marine business before he came to Caterpillar had taught him that any fuel system would have to be non-adjustable or else the company would face a litany of complaints as customers tried to "improve" engine performance by doing their own fuel system adjustments, a practice that continues today. An overhead cam, direct injection engine was also developed at that time, but was not put into production because of the narrower range of fuels that it would tolerate.

In October of 1931, Caterpillar introduced the D9900. While the D9900 produced a whopping 89 hp @ 700 rpm and weighed in at 5,175 lbs (2352 kg), it would revolutionize the industry. That is why the original D9900 can be found in the Smithsonian today. This was also the first diesel engine to be equipped with air-intake filters. The original D9900 is still in working condition, it was last run in the 1970's for emissions testing (it passed).

One of the first two Diesel Sixty's produced was sold to a California farmer named W. C. Schuder. After 27,000 hours of operation, he sold it to Clarence Danielson. Eventually it was purchased by a collector named Fred Heidrick, who maintains it in working condition today. While it took 250 years after the invention of the steam engine for portable steam power to be available on the farm, it took Benjamin Holt, Clarence Leo Best and C.G.A. Rosén one tenth of that time to evolve the steam traction engine into the modern diesel crawler.

With production gearing up, the East Peoria, Illinois plant boasted the world's only moving diesel assembly line. By 1933, Caterpillar's diesel engine production exceeded the total U.S. diesel production for the preceding year. In a few short, years Caterpillar had become one of the world's largest producers of diesel engines.

In June 1932, the first Caterpillar Diesel for use by another manufacturer was sold to the Thew Shovel Company of Lorain, Ohio. This D9900 powered a 1-1/2 cubic yard (1.2 cubic meters) power shovel. The Caterpillar Diesel offered greatly improved power, reliability and economy over both gasoline engines and competitor's diesels. Other original equipment manufactures soon saw the advantages of Caterpillar diesel power and adapted Caterpillar diesels to their applications.

The Engine Sales Group that was organized in 1932 was starting to meet with more success. Caterpillar engines, both diesel and gasoline, found their way into more and more applications, like this D7700 powering an irrigation pump in Colorado. Sales climbed from thirteen engines to nine different OEM customers in 1932 to 3,430 engines sold to 136 different OEM customers nine years later. Originally, engines were sold "as is," they didn't even have flywheel housings, but eventually Caterpillar developed the "Power Unit" concept of an engine, radiator, air cleaner and cowling on an I-beam base that was sold as a unit.

Caterpillar diesels had an advantage over many competitive engines because Caterpillar engines had been initially designed for tractors. Remember that this was an era where features like enclosed push rods and oil bath air cleaners, standard on Caterpillar engines, were considered unnecessary luxuries by other manufacturers. (In fact, in his book, "My Days With Cummins Diesel," Clessie Cummins talks about the failure of a Cummins Model F engine in an unnamed power shovel because of its exposed "rocker arms, push rods, camshaft bearings and some other moving parts..."). Just as diesel power was beginning to take hold, the world caved in on the young industry. Engines that had gone 3,000 hours without ring sticking or liner scuffing were suddenly dying at 300 hours. As the piston rings got stuck in their grooves, the engine lost compression. As the engine lost compression, it lost power. Eventually, there would not be enough compression for ignition and the engine would not run at all.

The engine manufacturers blamed the oil companies and the oil companies blamed the engine manufacturers. It took several years before everyone realized that a new refining process introduced in the early 1930's had removed naturally occurring detergents from the crude oil. With the detergents gone, there was nothing to inhibit the formation of combustion by-products in the ring grooves, which eventually led to the ring becoming stuck in the groove and not sealing. At this point, a serviceman would have to pull each piston and scrape off the accumulated sludge after applying a boiling bucket of chemicals to the piston. Caterpillar knew there had to be a better way. In discussions with the Shell Oil Company, a chemical was identified that did not require boiling to remove the sludge. It was a chemical detergent. One enterprising serviceman started putting the chemical in the engine crankcase just prior to each oil change. As he drained the oil, he also drained the dissolved sludge. This process quickly evolved into adding small amounts of the detergent to the oil to replace the natural detergents that had been present in the crankcase oil just a few years before. From that point, the Shell Oil Company started adding the detergent during production back at the refinery.

In an effort to cut through the brand loyalty of consumers, and at the same time insuring that Caterpillar engines received the proper type of lubrication, Caterpillar started issuing certificates to oil companies whose detergent oil was approved by Engineering. Since other oil companies did not want to be left out, Caterpillar was put into a position of having to create standards for diesel engine lubricating oil. After investigation, Engineering was convinced that it was impossible (in 1935) to evaluate a lubricating oil on the basis of chemical and bench tests. They only had confidence in actually testing the oil in an engine. To facilitate this, the one-cylinder engines that Caterpillar used for development work were made available to the petroleum industry to test oil performance. One-cylinder oil test engines are still manufactured today.

In 1935 the eight-cylinder D17000 was introduced for industrial applications. The D17000 was Caterpillar's first non-captive engine. In other words, it was not designed to be used in any Caterpillar earth-moving product. It crushed rock, propelled boats, generated power, drove locomotives and served in hundreds of applications during its twenty-year production life. A common practice at the time, the D17000 was started by a small two-cylinder gasoline "pony" engine that was mounted above the flywheel. The fuel tank and muffler are visible at the rear of this engine. (Many D17000 engines are still on the job today.)

One of the D17000's many applications was providing power for locomotives. Here, four are seen during construction of a locomotive at the Davenport-Besler Locomotive Works. 1939 was truly a watershed year for the Caterpillar diesel engine business, with three major initiatives launched. Working in cooperation with the Louis-Allis Company, Caterpillar introduced a complete line of self-regulated generator sets. Although they appear large by modern standards, self-regulated generators were far simpler and more compact than the standard generators made up to that date. The economy and reliability of Caterpillar diesel engines made them ideally suited for power generation. Caterpillar also accepted responsibility for the complete package, engine, generator and switchgear, providing parts and service support from a single source.

1939 also saw the introduction of a complete line of marine engines. With the exception of the D17000, all were marine versions of tractor engines. Caterpillar Diesel Engines were tailor made for work and fish boat applications where a premium was placed on the kind of solid, reliable performance that Caterpillar Diesels delivered. These engines carried the Caterpillar reputation for power and reliability onto the water. They were sold as a complete package, including the marine gear and heat exchanger.

Back on land, certain truck owners who were looking for power, economy and reliability were repowering trucks with Caterpillar Diesels removed from tractors or purchased outright. In 1939, truckers who wanted Caterpillar Diesel power got a boost from the factory when Caterpillar introduced their first truck engine, the D468. The six-cylinder D468 was rated at 90 hp @ 1800 rpm, and was sold complete with transmission. At the time, only one truck in 10,000 had a diesel engine, so the D468's ability to run all day on $5 worth of fuel stood out. The engine did have its drawbacks, however, being a converted D4600 tractor engine, it weighed in at 2,120 lbs (962 kg), which was simply too heavy. The next year, a second truck engine, the 60 hp four cylinder D312, was introduced.

Production of both truck engines, like much civilian production, was halted at the start of the Second World War. The military wanted crawler tractors with bulldozers such as this D4 on New Georgia Island in the Solomons. In the bloody battle for Tarawa (and others), Caterpillar tractors were used to bulldoze the firing positions of bunkers. Caterpillar equipment developed an immense reputation during the war for reliability and productivity. In many theaters crawler tractors with bulldozers were considered more important than tanks, and without a doubt they were one of the keys to victory in WWII, especially in the Pacific. Before the American entry into the Second World War, Caterpillar was asked to develop a diesel version of the current M4 Medium Tank engine, the Curtis Wright Cyclone. (The Wright Cyclone was a radial airplane engine. The use of airplane engines in tanks was a common practice in WWII because of their high output and low weight.) The original idea was for Caterpillar to develop an engine that could be retrofitted into existing tanks at rebuild and fitted into new production with a minimum of re-engineering. Working night and day, Caterpillar engineers had an operating engine in the test cell in less than six months.

It was a supercharged, air-cooled, nine-cylinder radial engine that developed 450 hp and could burn either diesel fuel or low octane gasoline. (In test, the engine developed as much as 875 hp, comparable to modern tank engines.) Tests in tanks showed the new engine to be a dramatic improvement over conventional gasoline engines in performance, reliability and safety. The early Army tests were held up for several weeks because the tremendous torque of the Caterpillar Diesel utterly destroyed the standard M4 clutches and propeller shafts. One engine destroyed its clutch and twisted its propeller shaft into three pieces on the first day. The transmission, which was made by Caterpillar, held together, however. But just as the revolutionary engine was going into production, the program was stopped. The Cyclone had been displaced in 1942 as the standard M-4 engine by a Ford gasoline V-8. The population of Cyclone powered tanks was rapidly diminishing and did not present an urgent repower requirement. Additionally, the Army of WWII was powered by gasoline; some within the military felt it would present supply problems to require two different fuels. In the end, only a single battalion was equipped with Caterpillar Diesel powered M-4 A-6 Sherman medium tanks.

Caterpillar had started the war as an American company with no overseas plants and small but significant export sales. Six years later, the Caterpillar name would be known throughout the world, carried by American combat engineers and SEABEES. A combination of the reputation Caterpillar would earn in the harsh conditions of combat and the acute need for tools to rebuild two shattered continents would transform a postwar Caterpillar into the multinational company that it is today. After World War II, Caterpillar launched a period of unparalleled growth. For the first time since the old Aurora Engine Company, Caterpillar established a dedicated engine facility, Building KK in East Peoria, Illinois, U.S.A.

There had been many advances in engine design during the war and Caterpillar was anxious to exploit them. New models, many of which had been authorized before the war, were introduced in quick succession. The 12-cylinder, 500 hp (373 kW) D397 and an 8-cylinder version, the 300 hp (224 kW) D375, were the largest diesel engines mass produced on an assembly line anywhere in the world at their introduction. By 1950, Caterpillar's industrial engines ranged from 30 hp to 520 hp (22 kW to 697 kW) and included 36 models. Additionally, in 1953 the Industrial Engine Division replaced the Special Engine Sales Group that had been established twenty-two years earlier, underscoring a deepening commitment to the engine business.

In 1957, the in-line 6-cylinder D353 was introduced, the first of a new 6.25" (159 mm) bore, 1200 rpm family. A V8 (the D379), V12 (D398) and a V16 (D399) were also added. The 6.25" bore engines were produced through 1990, a 33-year production run.

In 1955, Caterpillar first offered turbocharging, boosting power while reducing emissions. Turbocharging was followed quickly in 1958 by aftercooling, which lowers charge air temperatures for more efficient combustion and lowered emissions.