Crane Rating Question

New owners of a 70's vintage (pre-OSHA) BE Hy-Dynamic rough terrain crane, trying to rationalize the load chart on the machine. It came without a block, not a problem. It's claimed rating is 25,000lbs, with two 1/2" sheaves on the boom. The load chart shows a single-line rating of 6,250lbs, which works for a 4-line reeving except I can't find a 1/2" wire rope with that WLL at a 5:1 safety factor - the best I can find is 8x25 with a WLL of 4,640 for a 4-line rating of 18,560. Any ideas about...

Crane Rating Question

Crane Rating Question