Onesiphore Pecqueur
Today, let us meet Onesiphore Pecqueur. The University of Houston presents this series about the machines that make our civilization run, and the people whose ingenuity created them.
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Well, there’s a mouthful – Onesiphore Pecqueur. He was born in France in 1792. And he became a clockmaker. He was good at it. He won a gold medal for a watch he’d created when he was twenty-seven. It had two linked dials that displayed both conventional and sidereal time.
Then, five years later, Pecqueur took an interest in James Watt’s new steam engines. So, he designed a steam car. Watt himself had opposed using steam engines to drive vehicles. But no matter. Pecqueur got a French patent for his design.
The car was never built, but the patent application included a device that solved a problem no one else had anticipated. Such a vehicle would normally have two axles with only one driven by the motor. In his case, and in most of our cars today - certainly not all of them - the rear axle is the driven one.
Okay, now let’s turn left at a corner. When we do, the left-hand front wheel turns more slowly than the right. No problem since each wheel is independent. But if the rear axle is driven – at the same speed on both sides – that means trouble when we turn a corner. You’re likely aware that, today, our rear axles are split in two, with a gear box in the middle. It lets the two sides rotate at different speeds while we drive them. That gear box is our so-called differential gear.
Modern automobile differential gear (courtesy, Wikimedia commons)
Pecqueur invented that gear box. To see how it works, you and I need to watch one of the many online videos. But he completely described it in his patent drawing for his steam car.
Now: I say much in this series about how hard it is to find any invention without antecedents. Some historians have suggested that the ancient Chinese South Pointing Chariot used a differential gear. It was a chariot that carried a figure who always pointed south, no matter which way the chariot turned. Some have suggested that it used some kind of a differential mechanism.
Well, maybe. But too many competing theories are more plausible. We must look, instead, at Pecqueur’s previous life. Watches, as it turns out, have long used differential gears. Ones that let two related motions differ while they drive a common output motion.
So, it seems, Pecqueur was the right person at the right time – the one to carry a very clever, and far from obvious, mechanism from one application to another far different one.
Does that minimize his accomplishment? Hardly. That would deny that inventions have causes. So, my hat is off to this unsung maker of the machine that rides in your car and mine, to this very day.
I’m John Lienhard, at the University of Houston, where we’re interested in the way inventive minds work.
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Wikipedia article about Onesiphore Pecqueur https://en.wikipedia.org/wiki/On%C3%A9siphore_Pecqueur
https://www.pecqueurmotorists.com/en/the-pecqueur-differential-mechanical-genius-on-your-wrist
Differential (mechanical device) - Wikipedia
South-pointing chariot - Wikipedia
Pronounce Onesiphore Pecqueur approximately Oh-NAY-sih-for PECK-er
This video is one of many that we can find online which explain differential action. You might find one that you find more to your liking. Bing Videos
https://www.vitav.fr/onesiphor-pecquer-un-genie-oublie-de-la-mecanique/?utm I include a translation below. And urge you to note that the Papin reference is incorrect. Papin died in 1712, long before Pecquer, and he never built a steam carriage.
Onésiphore Pecquer: a forgotten genius of mechanics – a Clockmaker and pioneer of automotive mechanics. The work of Onésiphore Pecquer (1792-1852) led to major advances in the field of mechanics. This engineer is notably credited with the creation of the differential, in 1828.
Born in the Amiens region (Picardy), Onésiphore Pecquer was not only a clockmaker but also a mathematician, physicist, chemist, and mechanic. He became known in 1819 for creating a clock that, through the communication and interdependence of its gears, could indicate two different measures of time -- sidereal and mean. His popularity grew even more in 1825 when he developed a rotary steam engine. Pecquer made headlines again when he filed a patent on April 25, 1828, for a steam carriage. This carriage had a steam engine at the front that transmitted energy to the rear wheels, allowing them to operate independently of each other in terms of rotational speed. The goal of this invention was for the carriage to be able to turn smoothly. This is how the differential came into being. However, it was not until 1860, three years after Onésiphore Pecquer's death, that the first steam carriage was built by the famous Denis Papin -- a major Invention. While the invention of the differential revolutionized the field of automotive mechanics, the life of its inventor was long forgotten. Today, however, the genius of this mechanic has regained recognition. As late as 1934, the Quillet Encyclopedic Dictionary stated in the entry for “differential” that “the name of the inventor” remained unknown.
Pronouncing Onesiphore Pecqueur as oh-NAY-sih-for peck-ER
This Episode first aired on March 2, 2026.