Air-jet spinning process (wire rope)
The air-jet spinning process is a process for the production of parallel wire ropes for the suspension cables of a suspension bridge .
This term is actually a wrong expression, since the wires are laid parallel and not twisted ( spun ). It has nothing to do with the air-jet spinning process in the textile industry.
First, for the workers on the pylons leading narrow walkways ( catwalks ) set up to have the same slack as the future extension cable. Then a continuous endless tow rope is installed over each catwalk, which is driven by a drive pulley at one end of the bridge (anchor block) and guided around a pulley at the other end.
The large reel with the steel wire for the bridge is set up at its end; the free end of the wire is attached to the anchor block next to it. The wire is hung in a loop over a pulley that is attached under the tow rope. The pulley is pulled over the pylons by the tow rope, winding the wire from the reel while its end is still attached to the anchor block. At the other end, the wire loop is hung over the cable saddle, the pulley is pulled back from the tow rope and unwinds more wire from the reel. This loop is hung over a cable saddle at the first anchor block and the process begins again.
The wires are then aligned next to each other, bundled into strands, compressed by rope press machines under high pressure to form a suspension cable and then sheathed.
This procedure can take several months for large suspension bridges. For the Golden Gate Bridge , the air-jet spinning process took six months and nine days for both suspension cables. For each suspension cable, 27572 wires were pulled over the pylons.
John August Roebling developed the process to readiness for practical use and received a patent for it in the USA, relying on preliminary work by Louis-Joseph Vicat .
Individual evidence
- ^ Gerhard Mehlhorn, Manfred Curbach (Ed.): Handbook bridges . 3rd edition, Springer-Vieweg, Wiesbaden 2014, ISBN 978-3-658-03339-2 , p. 605 and p. 607, Fig. 6.7-2
- ↑ Patent US4945 : Apparatus for passing suspension wires for bridges across rivers. Registered on January 26, 1847 , applicant: John A. Roebling, inventor: John A. Roebling.