John Roebling didn't invent the suspension bridge, yet he is well-known for building the Brooklyn Bridge. Roebling didn't invent spun wire roping, either, yet he became wealthy by patening processes and manufacturing cables for bridges and aqueducts. "He was called a man of iron," says historian David McCullough.
From Germany to Pennsylvania:
- 1831, sailed to Philadelphia, PA with his brother Karl. They planned to migrate to western Pennsylvania and develop a farming community, although they knew nothing about farming. The brothers bought land in Butler County and developed a town eventually called Saxonburg.
- May 1936, married Johanna Herting, the town tailor's daughter
- 1837, Roebling became a citizen and a father. After his brother died of heatstroke while farming, Roebling began working for the State of Pennsylvania as a surveyor and engineer, where he built dams, locks, and surveyed railroad routes.
- 1842, Roebling proposed that the Allegheny Portage Railroad replace their continually breaking hemp coil ropes with steel coil ropes, a method he had read about in a German magazine. Wilhelm Albert had been using wire rope for German mining companies since 1834. Roebling modified the process and received a patent.
- 1844, Roebling won a commission to engineer a suspension aqueduct to carry canal water over the Allegheny River near Pittsburgh. The aqueduct bridge was successful from its opening in 1845 until 1861 when replaced by the railroad.
- 1846, Smithfield Street Bridge, Pittsburgh (replaced in 1883)
- 1847 - 1848, the Delaware Aqueduct, the oldest surviving suspension bridge in the U.S. Between 1847 and 1851 Roebling built four D&H Canal aqueducts.
- 1855, Bridge at Niagara Falls (removed 1897)
- 1860, Sixth Street Bridge, Pittsburgh (removed 1893)
- 1867, Cincinnati Bridge
- 1867, Plans the Brooklyn Bridge (Roebling died during its construction)
- 1883, Brooklyn Bridge completed under the direction of his oldest son, Washington Roebling, and his son's wife, Emily
Elements of a Suspension Bridge (e.g., Delaware Aqueduct):
- Cables are attached to stone piers
- Cast iron saddles sit on the cables
- Wrought-iron suspender rods sit on the saddles, with both ends hanging vertically from the saddle
- Suspenders attach to hanger plates to support part of the aqueduct or bridge deck flooring
Cast iron and wrought iron were new, popular materials in the 1800s.
Restoration of the Delaware Aqueduct:
- 1980, bought by the National Park Service to be preserved as part of Upper Delaware Scenic & Recreational River
- Almost all of the existing ironwork (cables, saddles, and suspenders) are the same materials installed when the structure was built.
- The two suspension cables (see red enclosure in picture) are made of wrought iron strands, spun on site under the direction of John Roebling in 1847.
- Each 8 1/2-inch diameter suspension cable carries 2,150 wires bunched into seven strands. Laboratory tests in 1983 concluded that the cable was still functional.
- Wrapping wires holding the cable strands in place were replaced in 1985.
- In 1986, the white pine wooden superstructure was reconstructed using Roebling's original plans, drawings, notes, and specifications
Roebling's Wire Company:
In 1848, Roebling moved his family to Trenton, New Jersey to start his own business and take advantage of his patents.
- 1850, established John A. Roebling's Sons Company to manufacture wire rope. Of Roebling's seven adult children, three sons (Washington Augustus, Ferdinand William, and Charles Gustavus) would eventually work for the compnay
- 1935 - 1936, oversaw the cable construction (spinning) for the Golden Gate Bridge
- 1945, provided the flat wire to the inventor of the Slinky toy
- 1952, business sold to the Colorado Fuel and Iron (CF&I) Company of Pueblo, Colorado
- 1968, the Crane Company purchased the CF&I
Wire rope cabling has been used in a variety of situations:
- suspension bridges
- cable cars
- ski lifts
- pulleys and cranes
- mining and shipping
Roebling's U.S. Patents:
- Patent Number 2,720, dated July 16, 1842, "Method of and Machine for Manufacturing Wire Ropes"
"What I claim as my original invention and desire to secure by Letters Patent is: 1. The process of giving to the wires and strands a uniform tension, by attaching them to equal weights which are freely suspended over pulleys during the manufacture, as described above. 2. The attaching of swivels or of pieces of annealed wire to the ends of the single wires or to the several strands, during the manufacture of a rope, for the purpose of preventing the twist of the fibers, as described above. 3. The manner of constructing the wrapping machine....and the respective parts of which are combined and arranged, as above described, and illustrated by the accompanying drawing, so as to adapt it to the particular purpose of winding wire upon wire ropes."
- Patent Number 4,710, dated August 26, 1846, "Anchoring Suspension-Chains for Bridges"
"My improvement consists in a new mode of anchorage applicable to wire bridges as well as chain bridges...What I claim as my original invention and wish to secure by Letters Patent is -- The application of a timber foundation, in place of stone, in connection with anchor plates, to support the pressure of the anchor chains or cables against the anchor masonry of a suspension bridge -- for the purpose of increasing the base of that masonry, to increase the surface exposed to pressure, and to substitute wood as an elastic material in place of stone, for the bedding of the anchor plates, -- the timber foundation either to occupy an inclined position, where the anchor cables or chains are continued in a straight line below ground, or to be placed horizontally, when the anchor cables are curved, as exhibited in the accompanying drawing, the whole to be in substance and in its main features constructed as fully described above and exhibited in the drawing."
- Patent Number 4,945, dated January 26, 1847, "Apparatus for Passing Suspension-Wires for Bridges Across Rivers"
"What I claim as my original invention, and wish to secure by Letters Patent, is -- The application of traveling wheels, suspended and worked, either by a double endless rope, or by a single rope, across a river or valley, for the purpose of traversing the wires for the formation of wire cables, the whole to be in substance and in its main features, constructed and worked, as above described, and illustrated by the drawings."
Archives and Collections for Further Research::
- John A. Roebling Collection, National Museum of American History, Smithsonian Institution
- The Roebling Museum, Roebling, New Jersey
- The Delaware and Hudson Canal Slide Show, National Park Service, U.S. Department of the Interior
Books Related to Roebling:
Spanning the Industrial Age: The John A. Roebling's Son Company, Trenton N.J. 1848-1974 by Clifford W. Zink and Dorothy White Hartman
Sources for this Article:
*The Great Bridge by David McCullough, New York: Simon and Schuster, 1972, Chapter 2
*John Roebling, Upper Delaware, National Park Service
*Roebling's Delaware Aqueduct, National Park Service
*Allegheny Portage Railroad, History and Culture, National Park Service
*Roebling and the Brooklyn Bridge, The Library of Congress
*"Modern History of Wire Rope" by Donald Sayenga
*United States Patent and Trademarks Office, Department of Commerce
*All websites accessed June 11, 2012