Mechanical safety fuse link

A mechanical safety fuse link apparatus for use as a serial element in a load lifting line, to extend telescopically from a short length to a longer length when load lifted by way of the link causes slipping of a linear slip clutch in the apparatus, the apparatus comprising:

• a) a telescoping body, having first and second members, capable of telescoping between a first length and a longer second length, with limiter means to prevent separation of said body;
• and
• b) a linear slip clutch, in the body, arranged to retain said body in said short length condition until a preselected load is imposed on said load lifting line, and to release said body from said first length when the preselected load is exceeded.
• c) said linear slip clutch comprising a peripheral groove in the surface of said first member, and adjustably bias loaded dogs on said second member arranged to be forced radially out of said groove to allow said slipping, the adjustable bias arranged to deliver force to said dogs through pivoting linkage, said pivoting linkage arranged such that a given bias delivers a maximum radial load to said dogs when the dogs are in the groove, and to deliver less than said maximum radial load to said dogs when the dogs are forced out of said groove.