I did some more searching for parbuckle, and found many sites that mentioned it, so that it is clear it is a fairly common term in mechanical engineering. I even found it used in a site about Paul Bunyan!
"The Winter of the Deep Snow everything was buried. Paul had to dig down to find the tops of the tallest White Pines. He had the snow dug away around them and lowered his sawyers down to the base of the trees. When the tree was cut off he hauled it to the surface with a long parbuckle chain to which Babe, mounted on snowshoes, was hitched."