PDFWAC 296-96-24655
Sheaves and supporting members.
(1) The minimum sheave diameter shall be 40 times the diameter of the rope used. For example, a 9.525 mm (0.375 in.) rope requires a 381 mm (15 in.) diameter sheave.
(2) The overhead supporting members shall be designed, based upon impact loads, with a safety factor of:
(a) 9 If wood; and
(b) 5 If steel.