A 2000-ft mine hoist operates with a 72-in drum using 6 x 19 monitor-steel wire rope. The cage and load weigh 8000 lbf, and the cage is subjected to an acceleration of 2 ft/s2 when starting.
(a) For a single-strand hoist how does the factor of safety n = Ff /Ft vary with the choice of rope diameter?
(b) For four supporting strands of wire rope attached to the cage, how does the factor of safety vary with the choice of rope diameter?