At its most basic level, a belt is a looped strip of flexible material used to bind two or more rotating shafts mechanically. They can be used to transfer objects, transmit mechanical power efficiently, or monitor relative movement.
Early uses of belts
For centuries, belts, ropes, and chains have been used as traction devices. The Babylonians and Assyrians reportedly used chains for water drawing machines. These first belts were flat and operated on flat pulleys.
A Chinese text from 15 BC makes the earliest mention of a mechanical belt drive with a pulley machine. The text explains how it was set up for weavers' shuttles to wind silk fibers onto bobbins. Approximately 1,000 years later, when the world's first known mechanized spinning wheel was recorded as having come from China, it relied on a belt drive.
By 1430, interest in the mechanical uses of belts continued to grow, and link chains even turned up on one of Leonardo da Vinci's sketches. Later on, the first theoretical essays on the traction mechanism (a different type of system) were published by Leonhard Euler (mathematician, 1707- 1783). The engineer Johann Albert Eytelwein (1764 - 1848) developed the Eytelwein equation in 1808 based on these essays, a concept still indispensable today for measuring frictionally engaged, non-positive drives.
Belts come into their own during the industrial revolution.
A power transmission drive with flat belts made of chrome leather became the indispensable foundation for manufacturing during the industrial revolution, which started in England in the second half of the 18th century. These belts became increasingly commonplace in modern factories with the emergence of industrialization.
These belts and pulleys were the simplest and most powerful way to transfer power between shafts. Power transmission belts operated smoothly and quietly, helping avoid overload and jamming of equipment and protecting motors and bearings from load changes. They needed minimal maintenance and were incredibly efficient.
Enter the automobile
The timing belt system present in most cars on roads worldwide is the classic example of a standard usage belt drive system. The modern world's movement of people, materials, and goods is mostly made possible due to how well these timing belts worked, and that is not an exaggeration!
In the early 1900s, the United States had a much greater need for motor transportation than the nations of Europe, with its large land area and a hinterland of dispersed and remote settlements. A slightly higher per capita income and equal income distribution than European countries ensured great demand. Against this context, Henry Ford introduced the Model T in 1908, and William Durant created General Motors. The ensuing insatiable demand for automobiles led to the production in 1917 of the vulcanized rubber V-belt.
Belts continue to be an essential tool in today's industries
Power transmission belts continue to play an essential role in various industries and applications, from textiles to manufacturing. Still, they are less noticeable than in the past, as they are covered by the machine frame in many cases and perform their task 'under cover.' Similarly, timing belt systems continue to power most cars on the road.
Whether they are moving a fridge along during production or keeping all of our car engine valves working well as we commute to work, the belt system is likely to be an essential mechanism that improves our lives for many years to come.