A driller is pulling on a stuck drillstring. The derrick is capable of supporting a maximum equivalent derrick load of 500,000 lbf, the drilling line has a strength of 51,200 lbf, and the strength of the drillpipe in tension is 396,000 lbf. If eight lines are strung between the crown block and traveling block and safety factors of 2.0 are required for the derrick, drillpipe, and drilling line, how hard ean the driller pull trying to free the stuck pipe? Answer: 166,667 lbf.