Wheels Over Water: Spinning Multiple Wires
Previous posts in the New Narrows Bridge Series:
Laying the Cable Wires
The process of laying the wires begins by securing one end to the anchorage. This wire is then looped up and over the spinning wheel, and the top wire returns to the spool which feeds it. As the spinning wheel moves outward from the anchorage along the tram, the lower wire called the dead line — remains fixed, while the upper wire, the live line — is drawn out from the spools onshore, much like a fishing line after a strike.
As the wheel moves outward from the anchor, it lays both lines in their selected position — guided by the positioning forks and the saddles on both towers — until the opposite anchorage is reached.
Once the wheel reaches the opposite anchor, the loop (or loops) of wire are removed from the spinning wheel and placed around the strand shoe (see the previous post), a semicircular casting with grooves for the wires, secured by anchor bolts to the opposite anchorage. When 454 wires have made this journey, they are bundled into a single strand or tendon. A total of 19 strands comprise the final cable, which is then compacted, wrapped, and sealed with epoxy to form the final cable.
Next: Compacting the Cables.
