Think about this fact for a moment: humans have used horses and wagons for millennia. Yet, in the space of 100 years, less, actually, the use of horses had ended.
Most of us no longer have a connection to these beautiful animals or the really elegant inventions that shaped the wagons and buggies that were used for most of human civilization. True, the advances made for the creation of the humble axle did set up the use of axles in cars. How many of us think about this tool which was really the product of many years of trial and error investigation?

First came the wheel?
Not exactly. Remnants of sledges using rollers, not wheels, have been discovered n eastern Europe. There is a lot of discussion about the dating of these rollers and some estimates put it back to about 4000 B. C. (To my amazement, when I began researching wagons and horses, I discovered that Eastern Europe and the steppes were actually the home of many inventions that today we take entirely for granted. Axle is actually an evolved word (aks) from some Proto Indo-European tongue that spawned of the languages from Greek to German, Iranian to Celtic that we are familiar with today. Honey bees. Pigs. Sheep who were domesticated first for meat – they were short fibers so the wool was unspinnable. No one is sure whether it was a mutation or human intervention that created sheep with the wool we use today. )
But I digress.
Sledges had to be pulled by teams of oxen and were very heavy. Also, and this is where the axle comes in, they didn’t move smoothly. Drag is very important in the movement of objects since it pulls back. Think of trying to move something through heavy mud. Later wheeled wagons and of course our current cars don’t have drag – not from the wheels nor to this degree – because the wheels and axle and all the other pieces are constructed in such a way that the vehicle moves as though it is much lighter, without the clutch of another force holding it back. From mud to a smooth asphalt road, for example.
Are we to wheels yet?