Old Days: Belt and Pulley

Innovation has often transformed labor and industry. One example is the belt and pulley power transfer system, a technology that revolutionized how energy was used in farming and manufacturing.

Before the 19th century, work was done manually, relying on brute strength and simple tools to complete tasks that required considerable time and effort. In the late 19th century, the leather belt, pulley system, steam engines, and water wheels allowed power transfer sources to various machinery.

At its core, the leather belt and pulley system is simple and elegant. Typically made from durable leather, the belt loops around pulleys attached to different machines. Power is transferred from one pulley at the source to other connected pulleys and, consequently, the machines they drive.

The implications of this technology in rural America were profound. The system allowed for mechanizing tasks such as milling grain, sawing wood, and threshing crops in agricultural settings. Farmers could now operate multiple machines simultaneously, significantly increasing productivity and reducing the labor force’s physical demands. This change led to greater efficiency and paved the way for increased agricultural output, contributing to the growth of local economies.

In industrial settings and tiny workshops, this technology served as a backbone for enterprises that utilized various machines for woodworking, blacksmithing, and textile production. Artisans could use a single power source to run multiple tools, enhancing productivity and expanding the possibilities for rural businesses.

The pullies’ size controls the driven machine’s belt speed. When variable speed is required, and both the power source and the driven machine are stationary, the fixed length of the belt becomes an issue. One way this problem was solved was by using two sets of stepped pullies, with constant source rotation speed yet allowing variable rotation speed to the driven machine while keeping the belt length the same (See the second image.) The example above has five different speeds. This seems to be the basis for an early CVT. While this example belt is pretty short, these drive belts sometimes were 50 to 100 feet long. As better materials became available, leather belts were replaced and upgraded.

As a teenager, I worked summers for some farmers in the surrounding area. One of them had an old sawmill that was leather belt-driven. He used a Farmall H series tractor to power it. In the picture below, you can see the built-in belt pulley on the right side of the tractor. Belt tension and alignment were done by moving the tractor. This says something about my age (old as dirt) , but it brings back good memories, and I’m glad I got to experience it.

The pulley and belt photos were made outdoors in the high desert near Santa Fe, New Mexico, in 2016. I believe that climate helped to preserve them.