The Original Cummins Diesels

By Staff
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Courtesy of Ken Davidson, 60110, Cummins Engine Co., Inc., Columbus, Indiana 47201.
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Aden L. Hawbaker, 85S6 Talhem Road, Chambersburg, PA 17201, with his Thermoil engine made by Cummins for Sears, about 1920; 2 HP.
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(Courtesy of Ken Davidson, 60110, Cummins Engine Co., Inc., Columbus, Indiana 47201.)
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Thermoil 7 HP, =M74, shown by Dave Herbst, near Sacramento, at Galt, California, National EDGTA show; photo by Howard . Shideler, 2803 E. Highway 120, Manteca, California 95336.

40646, Cummins Engine Company, Inc., 1000 Fifth Street,
Columbus, Indiana 47201.

This article is reprinted from Cummins Clippings, magazine of
Cummins Engine Company, Inc., Columbus, Indiana. Permission to
reprint has been given by Ken Davidson, Editor. The article was
brought in by Aden L. Hawbaker, 8586 Talhelm Road, Chambersburg, PA
17201, owner of a restored Thermoil engine.

The first Cummins diesels were known as Hvid type oil engines.
They were built under a license granted by a Robert M. Hvid who
owned the U.S. patents for the fuel and combustion system. During
the years 1919 through 1922, Cummins built 1?, 3, 6 and 8
horsepower Hvid engines. All were single, horizontal-cylinder

Except for size, these engines were of the same design. The
details are shown on the cross section that appears with this

The Cummins Hvid engines were compression ignition engines. We
call them ‘diesels’ today. They had a precombustion chamber
into which fuel was fed by gravity through metering valves
controlled by the governor. The fuel was fed into the cup during
the intake stroke. During compression, the fuel would heat up and
partially vaporize. Then, when it reached ignition temperature, the
vapor would explode and drive the main fuel charge with the

Cummins never was able to resolve several problems with this
fuel system. First, the ignition timing varied with fuel quality,
air temperature, and other factors. Clessie Cummins’ first
diesel invention was a means to mechanically time the ignition. By
lengthening the fuel valve, he sealed off the orifices between the
cup and the cylinder until the proper time for ignition. This
invention enabled Cummins to get six horsepower from an engine that
was originally designed for five horsepower.

A second problem was rapid car-boning inside the pre-ignition
chamber cup because of the precombustion of the fuel. After a few
hours, the engine would lose power and the cup had to be cleaned.
While this was easy to do, most people who bought the engines had
neither the mechanical ability nor the inclination to clean the

A third problem was that people had trouble starting the engines
because they did not understand compression ignition. They tried to
crank against compression, the same way they started gasoline
engines then. Carl Hertel, Cummins Shop Superintendent, spent many
weekends in the field teaching people how to use the compression
release. One Saturday he went down to the Ohio River because
they’d had a complaint.

‘What the guy was doing,’ he said, ‘was cranking
against compression. You know how they worked? You threw up the
lever and pushed the valve in and you would get it spinning and
then just take the crank off and throw the lever down and it would
start. He just let the engine run. I went in there and shut it off.
He said, ‘Oh, you will never get it started. There is only one
man on this river strong enough to start it.’ I said,
‘It’s easy if you know how,’ and went in and started

The worst problem, at least the most dramatic, was that the fuel
valves leaked, resulting in overflowing and overspeeding. Hertel
told about going to Chicago to start one:

‘This I will never forget because I went up there and
started it for him. We were in there talking and left it running.
We got over against a horse stall and the flywheel cut through the

These engines were among the smallest ever built and Cummins did
not have manufacturing equipment capable of the necessary
precision. The Hvid system worked pretty well on larger engines
with bigger valves. Actually, Hvid engines-when properly
adjusted-ran on a true diesel cycle. The Cummins engine operated
best on kerosene, but advertising said that they could be run on
old butter, fish oil, crude oil, and just about anything else that
would flow and burn.

Cummins built and sold only 22 engines, all six horsepower,
during 1919. Then they got into a real fiasco.

While Cummins was developing and going into production of the
six horsepower engine, Sears Roebuck was having Hercules Engine
Company of Evansville design a line of Hvid engines of 1? to 9
horsepower for sale to farmers through their mail-order catalog.
When Hercules found that they could not produce all of the engines
Sears wanted, they suggested that Sears contact Clessie Cummins. As
a result, Cummins agreed to produce 4,500 of the 1? and 3
horsepower models-engines that hadn’t yet been built and
tested. Hercules built the larger sizes listed in the 1920 through
1923 catalogs.

Sectional view of Cummins oil engine.

Sears apparently was impressed with Clessie Cummins’
ignition timing device because part of the deal was for Cummins to
supply injectors for the six horsepower engines built for Sears by
Hercules. We sold over $10,000 worth of six-horsepower injectors to
Hercules in 1920.

Sears sold the engines as ‘Thermoil’ kerosene engines on
terms of ‘$5 down-thirty days trial-ten months to pay.’ The
farmers took advantage of these terms. They bought the engines,
used them for thirty days, returned them, and got their down
payment returned. Sears then returned these engines to Cummins.
Although most of the returns were runnable, they were all

An original (1919) Hvid engine; 3 HP, 1 cylinder, 600 rpm.

Cummins’ sales reached a peak of $25,000 in December, 1920,
and then collapsed to less than $5,000 in February, 1921. Engines
were returned faster than they were shipped. Returns actually
amounted to more than 20% of sales. For the next four years,
Cummins had little to sell. In some months sales were less than
$100, mostly for contract machining jobs that came in.

Cummins really benefited from , this sad experience because they
decided to develop a new fuel system independently of what other
companies were doing. Hans L. Knudsen was hired as Chief Engineer,
and it was largely through his work that a successful fuel system
was ultimately developed.

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