The evolution of the tractor

Uncover the history of and engineering behind tractors that are now so common in agriculture

Small front tyres and extra-large rear tyres make the tractor a rather unusual machine with an awkwardly perched driver trying to manoeuvre the bouncy vehicle. The precursor to this modern vehicle goes back to the end of the 18th century, when the Industrial Age in England and the steam engine started to replace tasks done by horses and oxen in the fields. But these engines were stationery and had their limitations. By the 1840s, a portable steam engine that could be pulled by a horse became popular.

The first petrol-powered tractor made its appearance in 1892. American inventor John Froelich created one with large steel wheels with metal lugs. The combination of big rear wheels and small front wheels became a basic design principle and continues to be in use. However, while the large steel wheels provided good traction in loose soil, farmer found them hard to use on soft soil. Here is a fun fact: The tanks built by the British and French for use in World War I were inspired by these tractors.

With rubber tyres replacing steel wheels in the 1930s, the tractors became more efficient and easier to handle as it had a better grip. The tractors’ big rear wheels are the result of careful engineering and design principles. They provide better traction and stability, distribute the weight evenly, reduce soil compaction, provide greater surface contact and enhance grip on various terrains including uneven and soft ground. The heavy tyres also help counterbalance the very heavy engine located at the front.

This is not all. The rear wheels also generate higher torque, enabling the machine to pull heavy loads easily. It also allows the engine power to be used efficiently and reduces fuel consumption. Finally, it helps keep the centre of gravity low, which enhances stability and makes it less likely to tip over. This keeps the driver safe.

So what do the smaller front tyres do? Their smaller size allows sharp turns, better control, reduces soil compaction and protects crops from damage.

Can you think of another vehicle with large rear wheels and small front wheels? Yes, Formula 1 racing cars, which are at the opposite end of the spectrum and one of the fastest land vehicles. But that is a story for another day.