Clessie Lyle Cummins and Cummins Diesel Engines
Rich Cregar, C.L. Cummins Jr, Al Ebron
(2005 National Alternative Fuels Training
Consortium Photo used by permission)
The father of the American diesel truck was born on December 27, 1888 in rural Indiana. His parents were farmers, and owned a place that made them a reasonable living. Farming was not glamorous, and most of the time it was tough, grueling labor, punctuated by periods of drought, floods, bugs, low prices, harsh winters, and always work, tough, never-ending work. There were no tractors, trucks, or cars.
A rural school was rudimentary, and aimed at keeping the children available for farm work should the need arise; largely repetitive, grueling, and boring. There was not much need or encouragement to continue on. Clessie Cummins never had any formal education beyond the eighth grade.
Mechanical things fascinated him; he was always seeking to see how things worked. His great ability was that not only did he grasp the principals, he was able to assemble things back they way they were, sometimes making improvements.
Steam engines were all the rage. In 1899, using molten cast iron poured into wood blocks that he had carved himself for molds, Clessie Lyle Cummins built his own engine, which he used to get water for his father’s farm. It was the talk of the area since he was only 11 years old.
Increasingly, it became obvious to all that farming was not going to be Cummins’ calling. He began to take mechanical jobs and odd bits of work to support himself. His local reputation made him a constant and decent sort of living. Finally, he settled in at a steady job with Nordyke and Marmon, which made Marmon cars.
Through a friend, he was hired by racer Ray Harroun, who fitted a Marmon-Wasp for a run in the first 500 mile race at the Indianapolis raceway, known as the “brickyard” because the 2.5 mile course was paved with bricks. Clessie was a member of the pit crew, and several of his suggestions were adopted to improve speed.
At the end of the day, Harroun won that first race of 1911. A sense of accomplishment and pride from that achievement went with Clessie all the days of his life.
One of Harroun’s sponsors, local banker William Irwin, was aware of Clessie, his reputation for precision, and, above all, his honesty. After the first Indianapolis 500, Clessie went to work for Mr. Irwin as a chauffeur and mechanic. The relationship blossomed and became, over time, much more than employer/employee. Each man held deep abiding respect for each other. Mr. Irwin always marveled at the mechanical and engineering acumen of Clessie Cummins. Adding to his resume, Clessie designed and built his own gasoline engine in 1915 right in Mr. Irwin’s garage facility.
Somewhere in 1917 or 1918, Clessie Cummins saw his first diesel engine, built in the Netherlands by the R.M. Hvid Company. He could not get enough information about it to satisfy his insatiable thirst for knowledge about this “oil burning” engine.
Through a series of letters and visits with local representatives, Clessie Cummins was granted a license from the Hvid company to build diesel engines in the United States. It was one of the first such agreements regarding diesels in the USA. Mr. Irwin was, by then, a National Director of the United States Commerce Department, which probably helped.
Using the license, Clessie Cummins founded the Cummins Engine Company at Columbus, Indiana in 1919. Mr. William Irwin, his former employer, invested liberally in Cummins company. The first installment was $10,000.
The Cummins Engine Company produced its first licensed diesel engine in 1920. It developed 8 horsepower, and was sold for use as a stationary power unit for things like water pumps. It brought in enough money and interest to keep the company going. Clessie worked, when he was not selling or fixing the engines, on improving the design, as well as creating an engine that was totally his own.
In 1921, Clessie was granted two of his 33 patents for diesel engines, for improved fuel delivery and manifolding techniques, which were used to improve the licensed engine, and were later applied to the first totally Cummins-designed engine, 1924’s Model “F.” It sold, but not at the rate expected by Irwin, who had now put $100,000 into the company.
Cummins had already secured an arrangement with Sears-Roebuck and Company to sell his engines through the Sears catalog. There wasn’t a farmer in the land at the time who didn’t know about or receive a Sears Catalog. [The old edition of the catalog also served a great secondary function in the outhouses of the farms when a new one arrived.] Mr. Irwin was not impressed. Sure enough, the farmers bought the engines, used them, then returned them to Sears for refunds when they were done with them! Mr. Irwin was rather upset, while Clessie remained on the search for ways to improve his designs, and ways to sell them in great numbers.
In June 1929, Clessie built another engine of his own design. It was not anything that we might envision today, a heavy inline 4 cylinder which didn’t turn much over 1,000 rpm. However, it was well made and a miser on fuel. Clessie convinced Mr. Irwin to allow him to fit an expensive late model Packard touring car with his engine. Mr. Irwin acquiesced, and the tourer was completed with small amounts of room to spare in the engine bay.
Selecting a good mechanic from his company to assist, Clessie Cummins drove the diesel powered Packard to New York City, to show it in the 1938 New York City Auto Show. It was an astonishing achievement. In the 600 miles, the diesel had burned 30 gallons — or $1.38 worth — of fuel! He had all the receipts, and signed statements from station operators, credible witnesses, and/or police to back it all up.
Arriving in New York, he found he could not participate in the Auto Show because he had not registered. Taking a page from Walter Chrysler, Clessie rented space across from the car show to display his remarkable car and diesel power. It made a big impression.
Now, the biggest obstacle to a huge increase in orders was Clessie Cummins himself. He had made no provisions for production lines. He had not anticipated the intense interest in his oil burner. Carefully and wisely, avoiding making promises or taking deposits, Cummins returned to Columbus to plan setting up his plant for a production line to manufacture the engine in quantity. It is not known how Mr. Irwin took the news.
A few weeks later, the huge stock market crash on October 29, 1929 put the country into a tail spin. Any interest in a diesel powered car was set back, and within a few short weeks, Clessie Cummins was looking at bankruptcy in the near future. His biggest supporter and critic, Mr. Irwin, came to inquire what he intended to do. Clessie didn’t know. Their close relationship kept the relationship afloat, and thus the specter of immediate receivership at bay. Mr. Irwin wanted Cummins to succeed.
Clessie worked harder. Around the end of December 1929, Cummins learned that a famed British racer, named Kaye Don, was going to be at Daytona Beach Florida in an attempt to set some land speed records on the beach. Clessie felt he had found a means to garner more publicity for his company. Reporters from all over the world would be there.
A Packard Roadster was acquired. Clessie had it carefully redone without any fenders. His diesel engine was fitted. Again, picking a good mechanic from his factory, Cummins set out for Daytona Beach in February 1930, at the wheel of the car he intended to race over the beach. After a leisurely 7 day trip, with no problems, the diesel powered Packard arrived at Daytona. Interest was very intense, with throngs of reporters eager to have a newsworthy item to report about.
Using receipts, reports done by police, and other credible witnesses along the 1,275 mile trek from Columbus Indiana to Daytona Beach (no interstate highways or real national highways), the diesel burned about $2.30 cents of fuel, for an average of 40 miles per gallon for the $.04 (4 cents) per gallon cost. The reporters were astounded, and dutifully the reports flew over the wires all over the world. Almost lost in the whole thing was a speed record set by Cummins of 80.3 miles per hour, a first for a diesel. After the records were set, Cummins and his mechanic set out for Columbus. Total miles came to 2,550, and total fuel cost, including that used for the record came to $4.75.
With the subsequent publicity, some inquiries were being made by truck operators, mainly for coast-to-coast heavy trucks. Cummins engines were ideal and several concerns began fitting diesels from Cummins in their truck tractors. This helped to keep the factory going, but Clessie Cummins had his sights set on something that would really gain fame for his engines.
Despite the glowing reports of increased ability to haul heavier loads, over longer distances, with far less fuel costs, the word about diesel engines for trucking was not getting out. Clessie decided that perhaps a longer run would induce more interest. Using the same Packard, he went coast to coast with it, experienced few problems, and spent $11.22 on fuel for the entire distance. It garnered local notoriety, but nothing nationally. The country was in the throes of an ever deepening worldwide economic depression.
Up the road from Columbus was Auburn, home of the famous Duesenberg Motor Company. Clessie Cummins contacted them to build a racer aimed at conquering the Indianapolis 500, and a new Cummins two seat racer was initiated. Clessie designed a four cylinder engine which took advantage of the dangerous Indy rules, which allowed a 6 litre or 366 cubic inch displacement. Converting a model “U” from its marine application was easily done. It had a 3 valve head, and put out 85 horses from 361 cubic inches. It was an anvil-like, tough engine.
Before Indianapolis, Clessie took a trip to Daytona Beach in 1931. Registration laws and regulatory items, like bumpers, were a far future thought back then. Driving through the biting cold in a two-seat roadster which most likely had no provisions for heat was not mentioned in news about Clessie setting a new world land speed record of over 100 miles an hour.
Once the new record was set, the mechanic and Clessie returned to Columbus driving the Duesenberg racer. It generated interest along the way. Duesenberg autos had acquired a formidable reputation, early on, and coined a new phrase along its way: “it’s a Duesey!” Clessie was also gratified about the incredulity expressed when people heard it was a diesel. Even though the racer was a Cummins design to fit the Cummins diesel, it was a plus that people thought it was a Duesenberg. The community that Clessie was seeking to garner respect from knew the origins of the design. That was the important part.
Arriving back in Columbus, after some discussion on design for the body, new sheet metal was fitted to the racer, making it shorter to fit the rules of the Indianapolis 500. The track owner was famed World War I aviator and national hero Eddie Rickenbacker, leading ace of the hugely successful American “Hat In The Ring” flying squadron. Clessie spoke with Eddie; rules had been loosened because attendance was becoming a problem, in the midst of the Depression. Rickenbacker sought to generate interest in any way he could, and having a diesel race would garner some folks to come and see it. The only requirement that Rickenbacker set for Cummins was to have to exceed a minimum lap time of 70 miles an hour. He may or may not have been well aware of the 100 mile an hour record recently set by the same racer in Daytona a few weeks earlier.
Testing began shortly thereafter. The car was never trailered. It was driven the 40 or so miles from Columbus to the race track and back for testing and on the race day.
Driver Dave Evans set a 4 lap qualification run of 96.871 miles an hour. While it wasn’t a speed record, it was a record for the first diesel powered car at Indy. The car was heavy, at 3,386 pounds, the second heaviest in the field. It was also slow, being way behind the pole setting laps of the previous champion, Billy Arnold, who ran at 116.080 mph. There was some real concern about the tires being able to withstand the weight along with the abrasive brick surface.
These concerns were all set to rest at the end of the 1931 Indianapolis 500. Dave Evans finished in 13th place overall. His average speed was a respectable at 86.170 miles per hour. He made no pit stops for the entire length. That is right, the entire 500 miles was run with no stops, all on the fuel in the tanks. The tires were worn, but held up well.
Mr. Irwin was convinced that Europe was an untapped market, and he and Clessie took the car to Europe in March 1932. They demonstrated the car in France, Italy, Switzerland, and England. Orders were sent back to Columbus for manufacture. Overall, it was a good trip, but still the sales that Irwin wanted, as well as the money he sought, did not rise to the level he expected.
The race and European tour accomplishment generated huge interest in the Cummins diesels. Trucking firms sent representatives to talk to Clessie. Sales, during the deepening depression, actually did rise. In the meantime, Clessie Cummins continued to make improvements on his engines, and garnered more patents for his work.
In 1932, large-truck maker Kenworth had an option of diesel power for the first time in any company-built truck (Kenworth also featured torsion bar suspensions as an early option). It was the Cummins 4 cylinder, 100 horsepower, HA4 model. Clessie decided that to generate further interest he would outfit a cross country truck, and go coast to coast with it and under diesel power.
Cummins also made arrangements to rent the Indianapolis Motor Speedway for a show of engine endurance, with a full week long running of the car. Except making stops for fuel, the 168 hour run covered 13,535 miles. The average speed was 80 miles an hour. Fuel mileage was calculated at 32 miles per gallon. Diesels tend to be more efficient at load than at rest. Fuel costs were not given, but, unofficially, it cost about 422 gallons of fuel, which totaled $16.88 [422 x .04]. Overall, highly impressive, but again, only local notoriety resulted.
Knowing that Kenworth was set to announce the availability of Cummins diesel engines in 1932, Clessie Cummins decided to make another coast to coast run, this time in a fully outfitted cross country tractor trailer outfit powered by his diesel engine. In 1931, a special built truck was assembled at the Columbus Indiana plant. It was fitted with two beds, plenty of storage for food, parts, and had a stove for cooking. Three men would make the trip, two mechanics and Clessie Cummins himself.
Clessie made an agreement with Continental Oil Company to supply all the fuel, lubricants, and one hot meal per person a day for the trip. The truck was shipped to New York City, where it was met by Cummins and the two mechanics. After a bit of fanfare for the local newspapers, the trio set off for the West Coast.
In Southern Illinois, the cooling system sprung a leak causing the engine to overheat. Improvising, the trio on board made temporary repair by using shingles from a road side shed. Limping into St. Louis Missouri, the truck paused for full repairs. The cooling system was made like new, and a fuel pump was brought in from the factory at Columbus to replace one that was ailing.
A bureaucratic wrangling was in the works. An earlier cross country trip for records, conducted by General Motors, had caused the collapse of 43 bridges along the route, because the choice for travel did not take into consideration that many bridges were not designed for heavy trucks. Seeing the new attempt coming along nearly the same route caused local Sheriff and state police officials to constantly stop and question Cummins as to the route he intended to take. They did not want their fragile infrastructure, in Depression era economic conditions, destroyed by some “damn fool in a truck trying to impress someone.” No bridges were collapsed by Clessie, but it meant constant detours to avoid bridges. In one instance they had to ford a river near Amarillo.
There were other mishaps. A valve rocker arm failed, causing raw fuel to spill onto the hot exhaust manifold. It caused a fire that ripped into the cabin, setting fire to the bottom of the seats, and burning one of the mechanics’ feet on the bottom. The damage was relatively minor and did not stop the trip.
A life changing experience occurred near Cajon Pass near Barstow, California. Coming down the grade, with Clessie at the wheel, the weak brakes failed. Frantically downshifting to slow down, Clessie was horrified when he observed a train crossing at the bottom. The caboose cleared the crossing seconds before the truck ran over the tracks at 30 mph.
While trying to slow the truck, Clessie woke up his “swamper” or loader, who was riding in the passenger seat. When asked why the driver would wake him up just before hitting the railroad crossing, the swamper replied, “because he didn’t want me to miss the biggest damned accident we ever was gonna have.”
It was a life changing experience that would lead to one of Clessie Cummins’ greatest inventions, late in his life. He never got over that feeling of impotence and terror.
Other than that, the run generated the publicity it deserved, with repeated widespread coverage. The total running time was 97 hours and 20 minutes, beating the previous record of 103 hours and 59 minutes. The speed averaged 33.03 miles an hour. The fuel mileage really wowed them at 15.75 miles per gallon. Total cost for fuel came to $11.22 over the 3,214 mile trip. Interest was huge from interstate firms, trucking outfits, and manufacturers. Orders began to pour in. Sales increased from 10 engines a month to 100!
Mr. Irwin began to see the kind of profits that he had originally envisioned. Clessie Cummins devoted himself to the full-time development of the diesel engine. Now, he had the funding to carry through on many experiments previously sidelined due to monetary restriction.
Indianapolis was always on Cummins’ mind. He returned to the Memorial Day Classic in 1934 with two cars, built to house his diesels. For the 1934 Indy race, only 15 gallons of fuel could be carried in the car, and only 45 gallons were allowed for the entire race, although two cycle diesels were allowed 55 gallons.
For the two years that Clessie had not been to the race, an in-house debate had raged over the advantages of two cycle diesels. For his part, Clessie had some healthy skepticism; up to that date, the most engines, including his own, used the Otto four stroke cycle. Two strokes were difficult to keep lubricated, and smoked pretty heavily. Diesel tended to make the smoking worse. Still, GM was rumored to be developing a two-stroke diesel.
To settle the issue, Clessie built a two cycle and a four cycle racing diesel, again having Duesenberg build two chassis. Two 364 cubic inch engines were made, built from aluminum and supercharged. Both cars qualified, with the 4 cycle in 22nd starting place, and the two stroke in 29th place. The 4 cycle made it to lap 81, driver Dave Evans blew the transmission on leaving the pits. A short time later, the two cycle came in, and the driver had burned his foot on the hot transmission casing. Evans jumped in the car for relief. For the rest of the race, the two cycle ran hot, blew clouds of grayish blue smoke, and churned its way through the field. Evans brought the car home in 12th place. It remains the highest finish for a diesel.
The cars were brought into the garage area. As the two cycle began to cool, unmistakable sounds of metal bonding itself to other metal were heard. The pistons, and other components, had literally melted into the sides of the block, seizing the engine up forever. Cummins was quietly furious. He slammed the garage doors, and he and another mechanic removed it from the car. It was loaded into the back of a truck. During the evening trip back to Columbus, a stop was made on a bridge over the White River. Cummins and two other men pitched the two cycle engine into the deepest part of the river below. Nothing was said. No more discussion about two cycle diesels occurred at Cummins. That policy remains in place to this day.
Clessie spent the next couple decades dedicated to his engines. He personally gained 31 additional patents. World War II erupted in 1941, and between the military and civil applications, Cummins diesel grew, expanded its facilities, increased its work force, training, benefits, and range of engines. All major trucking companies used Cummins engines. They were rugged, anvil reliable, made excellent power, and constantly delivered excellent fuel mileage.
By 1950, Cummins did not need to go back to racing. However, the Indianapolis 500 always stood just a short ways up that road. Clessie L. Cummins had gone into semi retirement, leaving his brother, Donald Cummins, also a great engineer, in position to operate the company. Whether it was something that Donald wanted to do, or it was Clessie wanting to finish a project started, Cummins went back to Indy in 1950.
The company had just introduced its newest engine, a 401-cubic-inch, 6-cylinder in-line beauty: the JBS 600. Initial reports about the engine had truckers, owners, and manufacturers raving. The engine was massive but many efforts had been made to lighten the engine with aluminum in the head, pistons, block, and other areas.
Contributing to the overall weight was the Roots supercharger, mounted directly on the front of the engine at the crankshaft pulley. It was that area that failed about lap 50, literally nearly shaking the engine apart. The race ended for the Cummins special on that day.
With the Korean conflict in 1951, Cummins again found itself swamped with military orders, necessitating quick expansion of its facilities. No one thought much about the Indianapolis race for 1951. However, Clessie was working on it during 1951, which would result in his greatest assault upon the race, and his best effort to date.
Clessie had been experimenting with turbocharging to replace the heavy superchargers. The rules gave blown diesels a maximum displacement of a 6.6 litre. Clessie and his brother Don were hot after it with a specially built racing engine of 402.6 cubic inches, lightened with aluminum and magnesium. Output was a serious 380 horsepower.
The chassis builder was Frank Kurtis, whose Kurtis Craft had built several winning cars for Indy. (He had also built several chassis for Chrysler Corporation in 1952, running stock-block V-8 hemi engines — the Chrysler cars were disqualified when the rules were hastily changed against the stock blocks). Kurtis had been experimenting with placing the driveshaft alongside the driver’s left hip, shifting weight, and lowering the overall height of the car. Mounting the engine on a horizontal plane, rather than vertical, added to the sleek design. At its cowl, the car was 23 inches tall! However, it weighed 3,100 pounds, compared to the 2,000 pound average weight of the other entries. The engine was 750 pounds on its own. Tire wear was going to be a factor if any serious racing was conducted to get the car to the lead.
Things began to look up quickly. On the first day for qualifying, as the first entrant on the track, the big diesel roadster completed its 4 lap qualification at 138.010 miles per hour, a new record. It stunned all the other 32 competitors, including Team Ferrari, the only foreign entry. The speed held, putting the car on the pole for the race. Clessie was very confident.
The main issue with the big diesel is that on initial acceleration, it could not keep up with the gasoline powered cars. Given its great speed, it quickly caught them, but it then had to pass them to regain its position. It was a worry, given that it would lead off on the pole, only to see that quickly evaporate until the initial inertia was overcome.
The Memorial Day race day flag fell, and as supposed, the roadster was passed by several cars. However, it held its own. By lap 70, the diesel began to belch huge clouds of coal black smoke, a clear indication that something was wrong. A pit stop was made, but two laps later, the car retired. Later, an inspection revealed that the air intake for the turbo charger had become clogged with bits of rubber from the race track. An ill placed inlet was the failure, not the engine itself.
Cummins left the racer untouched, placing it on permanent display in the main lobby of the Cummins building at Columbus. It remained there, on display, until 1968. A planned 50 year celebration in 1969 led to the car being torn down for a complete rebuild. Then an ugly truth was revealed! The crankshaft had cracked starting at the 2nd journal, and ran the entire length to the 6th journal. Had the turbo not clogged, the engine itself would not have lasted much over 5 laps more. People were sworn to secrecy about it, keeping intact the story that none of the Cummins engines at Indy had problems. It kept the “pancake” diesel engine going, with thousands of installations world wide in bus applications.
After taking more and more time away from the company, Clessie retired as Chairman of the Board at the age of 67. In 1955, he formed another company, Cummins Enterprises Inc. He held onto his famous patents, although he didn’t try to interfere with his “old” company. Later, he moved to California. He found interesting work with the Allison Aircraft Engine Company.
Clessie Cummins continually experimented with ways to use the truck engine to slow the whole rig down. Just prior to his release from his Cummins Engine Company in 1954, Cummins and his son, Clessie Lyle Cummins, Junior, found it — an “engine brake,” a valve lifter that slightly opens the exhaust valves to release compression, and prevents fuel from igniting. Using a switch mounted inside the cab, a driver can select the number of cylinders to use in engine braking the truck.
Clessie shopped the idea around to several manufacturers. All turned him down. He then went to his own company. They indicated that they were also not interested. Shortly afterwards, his nephew introduced the head of Jacobs Chuck Company (famous for the three-bit rotating drill chueck) to Clessie; by 1959, a lot of big rigs were equipped with the “Jake Brake” engine braking system. It is still an indispensable component of any big diesel rig, and is even part of some class 2-3 diesel pickups (such as those made by Ram).
Clessie quietly retired after working for the Allison Company in California. He passed away there on August 17, 1968, after writing a short autobiography, now long out of print and hard to find. His son expanded on it with his own biography of Clessie Cummins.
The “Jake Brake” continues to be manufactured in Bloomfield Connecticut, with great success.
At Cummins Engines, a 1989 contract for supplying diesel power to the Dodge Truck Division for its line of Ram pickups resulted, eventually, in a great deal of additional business. General Motors had diesel engines for its pickups since 1978, and Ford since 1983; Dodge, after dalliances with Mitusbishi and Perkins, would end up with the best powerplants of the Big Three. (See details on our Cummins 5.9 and 6.7 liter straight-six diesel engines page)
Cummins produced its 1.5 millionth diesel engine for the Dodge Ram in 2006, a year in which 80% of Dodge heavy-duty truck buyers went for the diesel option. There was even a plan to fit new Cummins V-engines into Dodge Ram 1500 pickups, which was well into the engineering phrase when it was put on hold and eventually replaced by VM diesels, possiby due to cost reasons (since that engine was used by Chrysler in other vehicles).