Tribology is a relatively modern term, coined only back in 1966 in the Jost Report. However, human interaction with tribology and its concepts go back to almost the birth of the human species. Over the course of this series, we’ll look at how humans have dealt with friction, lubrication and wear throughout the ages, and how tribology as a discipline has evolved over time.
You might be thinking: why would ancient, pre-industrial humans have to worry about friction, lubrication and wear? While the problems faced by modern engineers and tribologists are certainly very different in their applications, the science behind tribology has been an important part of human culture for millennia.
By rubbing sticks against each other (friction), the first humans created fire, allowing us to survive the cold and dark. The sharpening (wear) of rocks and sticks gave us the means to hunt and feed ourselves, while the greasing of wheel axles with animal and plant oils (lubrication) allowed one of the most important and influential inventions in human history to work at all!
Animal and plant oils were also used by the ancient Egyptians to help in their building projects, with engravings and artwork depicting vast statues being dragged across the ground on top of giant rollers or sleds, while liquids – most likely animal or vegetable oils – are poured in front of the rollers as lubricants as they are transported across the sands. The picture on the right is a restored version of a painting from the tomb of Djehutihotep, showing a man pouring liquid from a jug in front of the sled to help lubricate the sand!
This method would be repeated for the building of the Great Pyramids, with the huge blocks of limestone and granite dragged over the sand (and up slopes with up to a 20% incline!) on sleds.
Another great ancient civilisation even made use of bearings! An example of a wooden ball bearing that was used to support a rotating platform, and has been approximately dated at around 40 BC, was discovered in the remains of a sunken Roman ship in Lake Nemi, Italy.
The pre-industrial age also laid the foundations for how mechanical engineering and tribology would interact. The pre-industrial age covers so much history that the invention of ball bearings and gears – two of the most fundamental and widely studied components of tribological systems to this day – were created during this period.
Even famed inventor Leonardo da Vinci knew the benefits of reducing friction in mechanical systems, as between 1498-1500 he sketched a ball bearing component of his own design, that was to be used for his famous helicopter design! He also performed the first experiments on friction in 1493, writing the results down in one of his notebooks.
In 1699 near the end of the pre-industrial age, French scientist Guillaume Amontons published the re-discovered laws of friction first put forward by da Vinci. These laws (while not mentioning lubricants which change the laws considerably), still form the basic understanding of dry friction that is taught in schools today!
Amontons’ laws of friction are:
- The force of friction is directly proportional to the applied load.
- The force of friction is independent of the apparent area of contact.
With the dawn of the first industrial revolution in 1760, machine elements would start to play a much more important role in tribology, along with the improvements of lubricants, bearings, and gears. But that is all for next time…
Keep an eye out for the next instalment of our History of Tribology series, coming soon!