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Making Things Go Round And Round

By Dan Harshman

Back in the day when the Edinburg Mill was operating there was equipment and machinery running on all of the floors of the building. And all of it ran off something called a Line Shaft.  A line shaft is a power driven rotating shaft that transfers the power from a main source to many different pieces of machinery. You can still see the one that operated most of our Mill on the second floor of the Museum. 

Line shafts were used extensively from the time of the Industrial Revolution until the early 20th century; in our case until 1979 when the Mill ceased to operate. Prior to electric motors becoming small enough to be directly connected to a piece of machinery, the line shaft was used to supply power from a large main power source throughout a mill, workshop, or other industrial building. The central power source might have been a steam engine, animal power, windmill, turbine, or a water wheel like what originally powered the Edinburg Mill. Even when our Mill converted from water power to an electric motor, the line shaft was still used to distribute power throughout the Mill.

The line shaft that can still be seen in the Mill today is a typical example where the line shaft is suspended from the ceiling and runs the length of the area. The large drive wheel of the shaft lines up with the power source that is located in the basement of the Mill. A visit to the restaurant in the basement level will give you a chance to see where the actual power came from. 

Although there is an electric motor powering it today, the actual main drive wheels are still in place as they would have been during the water powered period. I’ve told you in the past about the two steel Fitz Water Wheels that supplied power for the Edinburg Mill the first 90 years or so of its operation. They were replaced by electric power sometime in the 1940s.

The flat steel and wooded drums in the basement were turned by either power source and transferred that power to the line shaft on the second floor of the Mill using a wide flat belt. These belts were usually tanned leather or cotton duck impregnated with rubber. 

Leather belts were fastened together in a loop using rawhide or wire lacing, lap joints and glue, or a type of metal fastener. Cotton Duck belts usually used metal fasteners or were melted together with heat. The leather belts were run with the hair side against the flat drums for the best traction. They needed to be cleaned and conditioned periodically to keep them in good working order.

The flat pulleys or drums were constructed of wood, iron, steel or a combination thereof. I’ve heard that the use of a metal gear or cogwheel was avoided in many mills like ours because of the high dust factor involved with grinding wheat. A spark from metal hitting metal could ignite the dust in the air causing a fire or dangerous explosion. A close look at our line shaft on the second floor will also show you that bearings were used in the hangers along the length of the shaft at certain intervals. The distance between the hangers depended on the weight of the shaft and the number of pulleys.

The shaft had to be kept aligned or the stress on it would cause it to overheat the bearings and ultimately could break the shaft. Bearings were usually the friction type and required regular lubrication. This was an important job in the mill to ensure that bearings did not lock up and malfunction.

Different sized pulleys were used in combination to vary the rotation speed of the shaft. For example, a 40 inch pulley turning at 100 revolutions per minute (RPM) would turn a 20 inch pulley at 200 RPM.

Pulleys could be solidly attached (“fast”) to the shaft while an adjacent pulley could turn freely (“loose”) on the shaft to be used as an “idler”. This allowed the belt to be maneuvered onto the idler to stop the power and back to the fast pulley to supply power. This arrangement was often used near a specific machine to provide a means of shutting the machine off when not in use. You might remember that this way of engaging a belt is what did in young Frankie Hottel when he tried to sharpen his ax. Often at the final belt that powered a machine, a pair of stepped pulleys could be used to give a variety of speed settings for the machine.

Starting in the basement of our Mill, the belt ran up through the ceiling to the first floor where the visitor center is now located. You can still see the protective cage in the corner where a large loom is now displayed. The belt continues through the ceiling of the first floor up to the Line Shaft’s large (around 4 feet in diameter) drive wheel. It goes over the top of that wheel and returns to the basement level to complete the loop. Today the belt doesn’t really make the entire loop because of fire separation requirements. 

But if it did, we would be able to start our line shaft turning again by activating the power source in the basement. We actually discussed doing this on a daily basis, but quickly realized that large spinning steel wheels weren’t the safest thing to have our visitors walking around.

A fun fact about something that is in our film The Burning that we show as part of the Museum. In the scene where local historian Richard Kleese is telling the Edinburg Mill’s Civil War story he is standing in the second floor area of the Museum. You might have noticed that the line shaft wheels are turning next to him. The power source for this was me. I was over at the other end of the shaft turning the large drive wheel by hand. I made it through two takes of the filming, but as I remember it, wasn’t too interested in there being a third take.

There is a smaller line shaft located on what is the forth floor of the Mill you can look up at when standing in the main room below it. It has much smaller wheels on it and we really don’t know if this is its original location in the Mill. But wherever it was, it would have been turning at a much greater speed than the larger line shaft on the second floor. 

I hope I’ve piqued your interest to come by the Edinburg Mill to check out a 19th century state of the art source of power. As you stand there looking at the large steel and iron wheels, try to imagine what it must have been like to have worked in a place like our mill. Wheels and belts spinning all around you operating the grain elevators and the racket of a hammer mill filling the air around you. I’m betting our old mill was definitely rocking and rolling back in the day.