How wire rope is made

A crane cable is a hundred or so thin wires twisted into strands, and the strands twisted again around a core.

stations: 6
things upstream: 26
raw sources: 12
steps from the ground: 6

The short version

Wire rope is made by twisting steel wires into a helix to form a strand, then laying several strands around a central core in a machine called a strander. The wires are high-carbon steel drawn to great strength. A core of fiber or steel carries lubricant, and finished ropes get loops, thimbles or clips.

Draw high-carbon wire

Rope wires are plain carbon steel with 0.4 to 0.95 percent carbon, drawn very hard so each thin wire is strong. Rope that runs over small pulleys needs wire that bends again and again without cracking.

Goes in
Steel wire
Spin wires into strands

Wires are fed from reels through barrels and twisted around a center wire into a helix, layer upon layer. In a parallel-lay strand, each outer wire rests in the groove between two inner wires, so they touch along a line instead of crossing in points.
Choose and fit the core

The center can be sisal or synthetic fiber, one strand of steel, or a complete small wire rope of its own. Fiber is the most flexible. A steel core resists crushing and lasts best in harsh conditions.
Lay strands round the core

A strander winds several strands around the core in a helix. The outer strands go in the opposite direction to the wires inside them, which helps the rope resist twisting under load.
Soak in lubricant

The wires slide against one another each time the rope bends, so it is lubricated inside. A natural fiber core can soak up to 15 percent of its own weight in lubricant and feeds it to the wires from within.
Terminate the ends

Ends are finished with a spliced eye or a loop held by U-bolt clips. A thimble inside the loop stops it bending too sharply and pinching the wires.

End of the lineWire rope Next it goes into elevator, suspension bridge cable, sailboat.

Worth repeating

Modern wire rope was invented by the German mining engineer Wilhelm Albert between 1831 and 1834, for mines in the Harz Mountains.
Albert's first rope had three strands of four wires each.
A wire rope can have broken wires and keep working, since the neighbors pick up the load, unlike a chain, where one bad link ends it.