A Closer Look: Line Shaft Systems

Normally in this segment of the blog we tend to focus on smaller artifacts that visitors might not regularly notice or know much about. However, this time around I thought I would cover a little bit about a very large object, or set of objects, in the museum that can surprisingly get overlooked, the line shaft power system and the motors that power it. A line shaft system is a method of power transmission from a rotating central shaft, through pulleys, and on to individual pieces of machinery or equipment. This was the standard system used in factories to power multiple pieces of equipment from the Industrial Revolution through the mid-20th century.

The main central shaft can be powered by any number of different energy sources, such as a water wheel, steam engine, internal combustion engine, wind, or electric motors (later in the early 20th century). The line shaft in use at the Kregel Windmill Company was fairly standard for the time it was built around 1879. The shaft runs latitudinal to the factory building and is mounted in the ceiling with belts running down to one piece of machinery or laterally over to multiple pieces ran off of one secondary shaft. The power is transferred from the shaft and pulleys (also known as millworks) to the machinery via flat belts. In the case of the Kregel Windmill Company, the belts are made from buffalo hide rather than cow leather, mostly because it is much thicker and a longer continuous belt can be made due to the much larger hide. In later years canvas and textured rubber belts were manufactured that were cheaper and easier to produce than hide belts. According to the 1910 Grand Rapids tool catalog we have in our reference library here at the museum, customers could purchase a 4" wide belt for $1.50 per foot. That means, considering inflation, that would come to $36.46 per foot today; a exorbitant price. 

Before the widespread use of electricity the main source of power for the Kregel Windmill Company line shaft system was a Van Duzen 14 hp gasoline engine, which was mounted inside the building with the exhaust piped out through the back wall. This engine would have been incredibly noisy and oily, making it the factory a rough place to work in those days. Since then these engines have become extremely rare and unfortunately the museum is not in possession of the Van Duzen engine owned by the Kregels. The only information we have to confirm their having owned one is a sales sheet from 1931 that shows them selling one and a worn out two-ball governor from that particular model on the front shelf in the factory. For those wondering, the engine was sold by the Kregels for $75; it is worth considerably more now since there are only a handful in existence. 

Van Duzen 14hp Gasoline Engine at Coolspring, PA

In getting back to the line shaft system itself, during the majority of its operation, maintenance was a serious issue to keep up with on a daily basis. Most of the bearings in a line shaft system are Babbitt, a poured, molded bearing material made from lead and tin that long predated the current standard of roller and ball bearings. Although Babbitt was a useful material it needed lubrication quite often to keep the bearing from seizing up or wearing down the soft material. In the small Kregel Windmill Company factory there are approximately 40 individual grease points for the 18 pieces of machinery. That's not counting the points where the shaft is mounted to the structural beams of the factory building, known as pillow blocks. These grease points would need to be oiled at least every couple days if not daily, depending on the frequency of use. At most the gas engine system could operate about 3 machines at one time, so the oiling frequency would be less in those years compared to 6 or 7 machines after the advent of electric motors. 

One of the first large-scale line shaft operations in the United States after the Industrial Revolution was the famous Lowell Mills in Lowell, MA. Beginning around 1828, line shafts were employed in those mills to power dozens of automated looms. Below is an incredible video that demonstrates the complexity of these line shaft powered mills.

Much like in the video, the pulleys (or commonly blocks) at the Kregel Windmill factory are made of wood. Wood was a great material to use for these line shaft blocks for a couple of reasons. Firstly, wood is readily available and these blocks can be made from scrap pieces of wood fitted together like a jigsaw puzzle to make any size block that was needed. Second, wood contains natural tannins that slowly leach out to the surface and act as a sort of dressing for the buffalo hide belts, meaning that they do not necessarily have to be dressed with pine tar or another sticky sort of treatment to avoid slippage. 

There are many interesting ways of using the belts on a line shaft system to perform different jobs. The orientation of the belts on the blocks allows for changes in the output speed, output direction, and various other desired modifications. By using different sizes of pulleys in different combinations, as well as various belt configurations, factories could connect two pulleys together in a myriad of ways. In fact, the pulleys did not even need to be in line with each other, as shown by just a couple of the following examples.

I hope this serves as a good general primer on the subject of line shaft systems in factories during the Industrial Revolution. There is obviously much more to these complex systems than what I have discussed here, but I just wanted to give a quick overview. I hope that if anyone is interested they will take the time to swing by the museum and have a look at our system to learn more. After all, the Kregel Windmill Factory Museum is one of only 13 places in the United States where you can see an intact, historic line shaft system. Although the system is functional, thanks to our renovation project, we aren't able to provide the public with demonstrations due to the safety issues that would cause. However, we have videos available to show just how the system works. So stop by and have a look, we'd be happy to show you!

May your blades always catch the wind!