By William Gurstelle
Rudolf Diesel and the Fire Piston
Welcome to the first installment of Remaking History, where I’ll trace the connections
between the science and history of an experiment or invention, and show you how
to re-create it as a project for your home workshop. If you have suggestions for a
Remaking History column, I’d love to hear them.
—William Gurstelle, firstname.lastname@example.org
Carl von Linde was dead tired. The eminent
engineer, considered the father of the modern
refrigerator, had just returned to his home in Germany from a lecture tour that took him to, among
other places, Malaysia. This being the late 19th
century, the voyage had taken months. Von Linde
had seen and learned much during his excursion
to Southeast Asia, and as a faculty member of the
prestigious Munich Technical University, he was
obligated to deliver a presentation on the results
and findings of his trip to students and faculty.
During his lecture, the fatigued Herr Doktor
felt the need for a nicotine hit. He paused and
withdrew from his pocket a small wooden cylinder
and plunger, which he called ein Feuerkoben. The
small device was a gift from the people he had
met on Penang Island in the Strait of Malacca. The
indigenous people of the region used it to start fires.
A person experienced in the use of the Feuerkoben,
or fire piston, could reliably provide hot, glowing
embers anytime they were needed, even under the
humid conditions of the rain forest.
At the lectern, von Linde slapped the plunger
down and the tinder inside ignited. He plucked out
a glowing ember and lit his cigarette with it. It was a
neat gesture; to the audience, it looked like he had
produced fire from nothing at all — no match, no
flint. The fire had magically appeared from the bottom of an empty, hollowed-out tube.
The concept was not lost on audience member
Rudolf Diesel, who was one of Professor von
Linde’s most promising students. Diesel had been
experimenting with the recently invented internal
combustion engine and was growing frustrated with
the spark-ignition engine’s inherent low efficiency.
166 Make: Volume 19
When von Linde lit that cigarette, a question jumped
into Diesel’s head: Could the same thermodynamic
process that ignited the tinder in the bottom of the
fire piston also ignite fuel in an internal combustion
engine? If so, perhaps here was a way to significantly
improve the engine’s efficiency. And as history
proved, it was indeed.
Unlike typical gasoline engines, the eponymous
and now ubiquitous diesel engine has no spark plug
or carburetor. Instead, the diesel engine works by
compressing fuel under very high pressures. When
the fuel-air mixture in the cylinder compresses, it
also gets very hot. In fact, it quickly exceeds the
flash temperature of the fuel and ignites it. The
compressed gas expands violently upon ignition
and pushes the compressing piston away with
enough force to easily turn a drivetrain.
Scientists had known for 100 years that compressing a gas in a closed, insulated space causes it to get
hot. In 1809, French scientist Joseph Gay-Lussac
conducted experiments that proved the temperature of a fixed mass and volume of a gas is directly
proportional to its pressure.
But it fell to Diesel to figure out how to use
this knowledge to make a high-efficiency engine
that could work with no need for a spark. Diesel
published a paper in 1893 outlining his ideas for a
spark-free, compression-ignition engine. In 1897, he
built the world’s first working compression-ignition
internal combustion engine.
Was von Linde’s fire piston the true antecedent
of the Mack truck engine? Well, accounts vary, but
one thing is certain: the fire piston is not only fun to
make and use, it’s scientifically interesting and historically significant. Here’s how to make your own.