For 85 years Cummins has been building power plants for America’s farm and construction equipment, 18-wheelers, motorhomes, pickups, and more.
By Jim Brightly
Technical Editor
July 2004
This is the second installment in FMC’s three-part series highlighting the major diesel engine manufacturers “” Caterpillar, Cummins, and Detroit Diesel “” that supply power plants for the ever-growing type A diesel-pusher motorhome market.
From Key West to Nome, from Bangor to San Diego, FMCA members know that the best way to get away is in a motorhome. And for many, there is no better vehicle to take them on their journey than a diesel-pusher coach. So when a motorhome owner opens the rear engine hatch and sees the Cummins name on the valve cover, he knows that he’ll have all the power needed for the coming trip. It’s called “Cummins Confidence.”
Company History
The word confidence has been associated with Cummins Inc., which has been based in Columbus, Indiana, throughout its 85-year history. In fact, it was a leap of faith that led to the formation of the Cummins Engine Company in 1919. That’s when W.G. Irwin, a prominent local banker and investor, took a chance on his personal chauffeur and mechanic, 31-year-old Clessie Lyle Cummins, who was interested in bringing a new engine technology “” diesel “” to the United States. Mr. Irwin supplied the capital that Clessie Cummins used to secure engine manufacturing rights from a Dutch company to build Hvid diesel engines.
The first Cummins-built Hvid engines were four-cycle, six-horsepower models that were used for stationary power applications. Unfortunately, the underdeveloped engines proved difficult to sell. So, with the help of H.L. Knudsen, a former Hvid engineer, Clessie Cummins set out to develop his own engines. Improvements were made, but the technology still lagged behind the more popular gasoline and steam engines used at the time.
To encourage engine sales, the company attempted several marketing approaches, none of which really worked. According to Cummins’ literature, “When Cummins engines were sold through the Sears catalog as ‘Thermoil’ models, farmers bought the machines, used them, shared them, and shipped them back at the end of the season under the retailer’s money-back guarantee.” This practice, coupled with the 1929 stock market crash that signaled the beginning of the Great Depression, created financial headaches for the struggling company.
While Cummins engines were being used in agricultural and marine applications, Clessie’s dream was to see them on the road. But the early diesel engines were saddled with a daunting problem: a weighty pound-per-horsepower ratio. The engines were just too heavy for the amount of power they could provide. So he began to whittle away the weight and boost the power, hoping to make the engine more viable for highway usage. Unfortunately, technology, even at that time, wasn’t cheap and the company was nearly bankrupt. Cummins needed money, but considering the dour economic times, he figured he’d have little chance convincing his principal financier, W.G. Irwin, to invest more in the failing company. But he had to try.
So he mounted one of his engines in a used Packard limousine and on Christmas Day 1929 took Irwin for a ride in America’s first diesel-powered car, demonstrating that diesel power was possible in automotive applications. The gamble worked, and Irwin agreed to entrust more of his money to the entrepreneur.
With the engine development side of the business on solid footing, Cummins turned his attention to popularizing the automotive diesel for the consumer, particularly the trucking industry. He decided that the best way to advertise the engine’s power, efficiency, and durability was through a series of demonstrations. During a two-year period Clessie and his Cummins team set a diesel speed record in a Duesenberg-bodied race car at Daytona Beach; made a six-day, 3,214-mile, coast-to-coast trip in a Cummins-powered truck for just $11.22 in fuel; and in 1931 established a nonstop endurance record of 13,535 miles at the Indianapolis Motor Speedway.
These feats attracted the attention of numerous truckers and fleet operators interested in switching over to Cummins diesels. In 1933 the company unveiled its powerful Model H, which would become Cummins’ most successful engine line. When word of the diesel’s many advantages began to spread, business took off. Finally, in 1937, Cummins posted its first profit.
Building An Engine Powerhouse
Business boomed in the following years, only to be stymied when World War II erupted in 1941, redirecting most of Cummins’ production to the military. Following the war, Cummins refocused its attention on consumer truck engine sales, which exploded in the 1950s during America’s interstate highway construction program. Cummins diesels powered much of the heavy equipment used to build the highways, which, once completed, became populated by trucks, many with Cummins engines under the hood. By the late 1950s, Cummins had established itself as the market leader for heavy-truck diesel engines, with sales of more than $100 million.
While enjoying success in America, Cummins began to explore overseas markets during the 1960s, opening plants or licensing manufacturers in Europe, Brazil, Australia, India, Mexico, and Japan. The company also realized that the demand for heavy-truck engines would not continue at the same pace, and Cummins officials began looking at other diesel engine opportunities, as well as associated systems. From this foresight sprang a number of other business ventures, including electrical power generation systems (Onan is among them), fuel systems, and air handling, filtration, and emissions products.
Faced with worldwide competition in the 1980s, Cummins invested $1.3 billion in new plants, equipment, and engine design. In the 1990s, the company focused even more attention on major manufacturing overseas, and also developed an extensive service network. Moving into the new millennium, Cummins’ winning formula continued: in 2003 it posted sales of $6.3 billion.
The Engines
Emissions are a major topic among diesel-engine manufacturers. By 2007, Environmental Protection Agency (EPA) standards require a significant reduction in the amount of oxides of nitrogen and diesel particulate matter released into the air. Well before this mandate and earlier emissions regulations that took effect in 2002, Cummins had been working to reduce emissions with its cooled exhaust gas recirculation (EGR) technology, which it began work on in the early 1990s. The process works like this: a small amount of hot exhaust air is routed through a cooler and then mixed with the fresh air going into the engine. The cooled exhaust gas helps reduce the temperature during combustion, which lowers the formation of oxides of nitrogen.
The company produces five engines (ISB, ISC, ISL, ISM, and ISX) that are used in the RV industry. Independent chassis manufacturers Freightliner, Spartan, and Workhorse all use Cummins engines, as do several motorhome manufacturers that produce their own chassis. In fact, the company estimates that seven out of every 10 diesel-powered motorhomes on the road today are equipped with Cummins engines.
The ISB is the most economical engine in the Cummins lineup. It is a fully electronic, 24-valve, in-line six-cylinder turbocharged diesel that produces 300 horsepower “” 30 percent more power than its predecessor “” with 10 percent more peak torque (660 pound-feet at 1,600 rpm). The ISB has an integrated exhaust brake for better driver control and reduced brake wear, a new electronic fuel system, and a variable-geometry turbocharger. Said to be up to 80 percent quieter than its predecessor, the ISB also runs cleaner and provides better fuel economy. The ISB holds four gallons of oil with a change interval of 15,000 miles or one year, whichever comes first.
The ISC, Cummins’ top-selling product, showcases full-authority electronics, 24-valve centered fuel injection, and is reportedly 50 percent quieter than previous models. With its high-pressure common-rail (HPCR) fuel system and Holset turbocharger, the ISC maintains high injection pressures regardless of engine speed. A combination full-flow and bypass oil filter increases piston ring and bearing life. The ISC holds 6.3 gallons of oil with a change interval of 15,000 miles or one year, whichever comes first.
According to Cummins, the ISL is the newest and fastest-growing engine in the motorhome market, offering excellent performance and sophisticated electronics. It provides RVers an outstanding combination of power and reliability. The ISL’s HPCR fuel system and patented Holset variable-geometry turbocharger increases both acceleration performance and stopping power when used in conjunction with the optional Jacobs compression brake. The ISL holds 7.3 gallons of oil with a change interval of 20,000 miles or one year, whichever comes first.
The ISM engine is designed for long-distance cruising with what is said to be the highest power-to-weight ratio in its class. The ISM’s technology includes a faster electronic control module (ECM), a Holset variable-geometry turbocharger, dual-pulse fuel injection, a Jacobs compression brake, and a redesigned piston bowl that is said to provide more power at the top end and more torque on the lower end of the rpm range. The ISM holds 10.3 gallons of oil with a change interval of 15,000 miles or one year, whichever comes first.
The ISX engine is touted by Cummins as “the first diesel of the 21st century,” with dual overhead cams, an integrated engine brake, and up to 600 horsepower. The dual overhead camshaft design delivers high performance, low emissions, and exceptional braking. The first cam drives high-pressure fuel injection for clean, responsive power. The second cam includes a dedicated set of lobes for the operation of the integrated engine brake, in addition to operating the intake and exhaust valves. The Holset variable-geometry turbocharger produces quicker throttle response, eliminating turbo “lag” for faster acceleration. Computer-controlled infinite adjustment provides the exact amount of boost needed at any engine speed. The ISX holds 14 gallons of oil with a change interval of 15,000 miles or one year, whichever comes first.
Through vision, technical know-how, and perseverance, Clessie Cummins revolutionized the automotive industry. And the company he founded continues to do the same to this day.
Cummins Inc., Box 3005, Columbus, IN, 47202-3005; (800) DIESELS (343-7357); www.cummins.com.
Engine Horsepower@rpm Torque (pound-feet@rpm)
ISB 300 300 @ 2,500 600 @ 1,600
ISB 300 300 @ 2,500 660 @ 1,600
ISC 315 315 @ 2,000 950 @ 1,300
ISC 330 330 @ 2,000 950 @ 1,400
ISL 350 360 @ 2,000 1,050 @ 1,300
ISL 370 370 @ 2,000 1,200 @ 1,300
ISL 400 400 @ 2,000 1,200 @ 1,300
ISM 450 450 @ 1,800 1,450 @ 1,300
ISM 500 500 @ 1,900 1,450 @ 1,300
ISM 500 500 @ 1,900 1,550 @ 1,300
ISX 525 525 @ 1,700 1,650 @ 1,200
ISX 600 600 @ 1,800 1,850 @ 1,200