1 Rope Selection ©Dr. B. C. Paul 1999 With Credit to Dr. H. Sevim for Original Book

2 Requirements for a Good Rope w Strong and Light Weight Choice is usually improved plow steel w Need to load each strand evenly (only as strong as weakest link) - special weave w Must be Flexible Bendability determines size of wheel or drum controls much of inertia

3 Making a Good Hoisting Rope w Can’t spin when it stretches Usual special weaves - often a left hand weave w Can’t spring and bounce under load not funny when hanging down 3000 ft shaft w Needs to be lubricated so wires don’t tear each other up oil also helps to fight rust center often oil soaked fabric

4 Three Major Rope Types w Round Strand least expensive best weight to strength ratio wears well has air space that doesn't add strength w Flattened Strand Shaped like triangle - to put high surface area on Keope Wheel No air space - all muscle may not wear as well

5 Rope Types

6 Last Rope Type w Locked Coil - tight locked out layer Used for maximum strength when everything else will break Very inflexible - may need big wheel if that deep anyway Locking structure can hide broken wires - remember in mine rope every strand is counted on to carry its share of weight

7 Safety Factors w Static Factor of Safety - deals with load just hanging there w Dynamic Factor of Safety - deals with inertia and acceleration forces too w Regulatory Strangeness Varies by Country and Hoist Type some by formulas some by steps increasing with greater depth US uses static but says they'll blame you if it fails on acceleration