A line shaft is a power transmission system used extensively during the Industrial Revolution. Prior to the widespread use of electric motors small enough to be connected to each piece of machinery, line shafting was used to distribute power from a large central power source to machinery throughout an industrial complex. The central power source could be a water wheel or turbine, animal power, a stationary steam engine, or a steam traction engine.
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History
Early version of line shafts date back into the 18th century, but truly came of age in the early 19th century industrialization and manufacturing. Line shafts were widely used in Manufacturing, woodworking shops, machine shops, saw mills and grist mills. Line shafting fell out of favor in the early-to-mid 20th century with the widespread availability of electrical power and availability of compact electric motors. Such independent motors are far less maintenance intensive than maintaining a line shaft system. Those systems in place tended to be converted to power from a large internal combustion engine or large electric motor. Some systems were broken up with separate motors driving different parts of what was one system. Most systems were out of service by the mid-20th century and relatively few remain, even fewer in their original location and configuration.
Operation
A typical line shaft would be suspended from the ceiling of one area and would run the length of that area. One pulley on the shaft would receive the power from the a parent line shaft elsewhere in the building. The other pulleys would supply power to pulleys on each individual machine or to subsequent line shafts. In manufacturing where there were a large number of machines performing the same tasks, the design of the system was fairly regular and repeated. In other applications such as machine and wood shops where there was a variety of machines with different orientations and power requirements, the system would appear erratic and inconsistent with many different shafting directions and pulley sizes. Shafts were usually horizontal and overhead but occasionally were vertical and could be underground. Shafts were usually rigid steel, made up of several parts bolted together at flanges. The shafts were suspended by hangers with bearings at certain intervals of length. The distance depended on the weight of the shaft and the number of pulleys. The shafts had to be kept aligned or the stress would overheat the bearings and could break the shaft. The bearings were usually friction type and had to be kept lubricated.
In the earliest applications power was transmitted between pulleys using loops of rope on grooved pulleys. This method is extremely rare today, dating mostly from the 18th century. Flat belts on flat pulleys or drums were the most common method during the 19th and early 20th century. The belts were generally tanned leather or cotton duck impregnated with rubber. Leather belts were fastened in loops with rawhide or wire lacing, lap joints and glue, or one of several types of steel fasteners. Cotton duck belts usually used metal fasteners or were melted together with heat. The leather belts were run with the hair side against the pulleys for best traction. The belts needed periodic cleaning and conditioning to keep them in good condition. Belts were often twisted 180 degrees per leg and reversed on on the receiving pulley to cause the second shaft to rotate in the opposite direction.
Pulleys were constructed of wood, iron, steel or a combination thereof. Varying sizes of pulleys were used in conjunction to change the speed of rotation. For example a 40" pulley at 100 RPM would turn a 20" pulley at 200 RPM. Pulleys solidly attached to the shaft could be combined with adjacent pulleys that turned freely on the shaft (idlers). In this configuration the belt could be manuvered onto the idler to stop power transmission or onto the solid pulley to convey the power. This arrangement was often used near machines to provide a means of shutting the machine off when not in use. Usually at the last belt feeding power to a machine, a pair of stepped pulleys could be used to give a variety of speed settings for the machine.
Occasionally gears were used between shafts to change speed rather than belts and different sized pulleys, but this seems to have been relatively uncommon.
Early Examples
In an early example, Jedediah Strutt's water-powered cotton mill in Belper, built in 1776, all the power to operate the machinery came from a single water wheel or steam engine. Power was distributed from this prime mover by the "rope race", a system of rawhide belts, ropes, pulleys and line shafts.
Preservation
A number of line shaft systems still exist. This list is in development.
Original Systems
- East Broad Top Railroad and Coal Company. Rockhill Furnace, PA (inoperable wood shop, blacksmiths shop, foundry)
- Longleaf Lumber Company/Southern Forest Heritage Museum, Longleaf, LA (partially operable - machine tools, sawmill)
- Sierra Railroad Shops/Railtown 1897 State Historic Park, Jamestown, CA (operable - machine tools, blachsmith shop)
- Empire Mine State Park machine Shop, Grass Valley, CA (??? - machine tools)
- Hagley Museum, Wilmington, DE
- Stott Park Bobbin Mill, Cumbria, England (???)
- Mingus Mill, Great Smokey Mountains National Park, SC (partially operable - grain mill)
- Hanford Mills Museum, East Meredith, NY (???)
- Slater Mill Historic Site, Pawtucket, RI (???)
- Thomas Edison National Historical Park, West Orange, NJ (??? - Machine Tools)
- W J Doran Company, Waupaca, WI, (fully operational - machine tools)
- Shelsley Watermill, Shelsley Walsh, Worcester, UK (partially operable - grain mill)
Reconstructed or Demonstration Systems
- Smithsonian Institution, Arts and Industries Building, Washington DC (machine tools)
- White River Valley Antique Association, Enora, IN (machine and woodworking tools)
- Cincinnati History Museum, Cincinnati, OH (machine tools)
- Henry Ford Museum and Greenfield Village, Dearborn, MI (machine tools)
- Molly Kathleen Mine, Clear Creek, CO (sawmill)
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