In 1842, Roebling pioneered the U.S. wire rope industry when he decided to try making large rope for hauling/towing applications not from hemp, a material that often would not last much more than a year, but from wire. He replaced a 3 in. diameter hemp rope for the Allegheny Portage Railroad with a rope made of low carbon iron wire that was less than half the size and lasted far longer.
“Our industry owes a lot to John Roebling, and it was an honor for us to do something that recognizes his accomplishments and makes others more aware of it”, said Mike Wallace, who in August presented a spool of wire rope to park service officials on behalf of the wire rope industry’s two primary trade associations: the Associated Wire Rope Fabricators (AWRF) and The Committee of Domestic Steel Wire Rope and Specialty Cable Manufacturers. Wallace, who is currently President of AWRF, works for Connecticut-based Loos & Co. Inc. , one of the few remaining U.S. steel wire rope makers.
At the request of AWRF Historian Don Sayenga and with the blessing of Loos & Co., Wallace and Loos Engineering Manager Curt Schopfer led the efforts at his company to manufacture the 31.75 mm replica. They explained that carbon steel wire, which has greater fatigue life than stainless steel, is typically used for applications such as hauling cars up a mountain. However, because the ropes were made to be in outdoor exhibits and to be handled by people, stainless steel was chosen because of its ability to resist corrosion.
A relic piece of rope confirmed the rope’s left-hand closing lay. “This along with the one-size wire records led us to build a 1-1/4 nominal diameter left regular lay 7 x 19”, Wallace and Schopfer explained. The strand core gives this product considerable stiffness compared to a standard IWRC or fiber core rope. Stainless steel was chosen for the replica because of its resistance to environmental deterioration. Also, the material was made relatively soft 100-130 kpsi, to replicate the tensile of the iron available in the period and to facilitate the fabrication process and subsequent handling. As a result, the rope stays together quite well and replica pieces do not require seizing. Wood closing dies were used to match the exact custom diameter of the rope. They also made it possible to fabricate the rope without damaging the exterior wires during the closing process.
Portions of the wire rope will be able to be cut off and displayed at various park locations so visitors can see and touch a piece of history. Observed Wallace and Schopfer, “Handling this rope gives people an appreciation of the monumental obstacles that these pioneers overcame in order to accomplish this task, all done by hand with no specially designed machinery”.
Roebling, a German-born engineer educated at the Bauakademie in Berlin, immigrated in 1831 to Pennsylvania, where he became an engineer for the state, supervising the construction of canals, locks, and dams. Through his position, he saw a rail application that relied on 10 hemp ropes that did not last long outdoors. He experimented with some 2 mm iron wire, and after an initial failure, he made a 7 by 19 left lay wire rope that proved successful.
The state began to switch over to Roebling's handmade product, marking the beginning of the wire rope industry in the U.S. He had a life-long interest in building suspension bridges and he later established a factory in New Jersey that was expanded by his sons into one of the world’s largest steel wire mills after his death in 1869. For more information, go to: Allegheny Portage, www.nps.gov/alpo; AWRF, www.awrf.org; and Loos Co., www.loosco.com. (Reprinted courtesy of Wire Journal International/Wire Association International)