Traditionally, locking line swivels are used when pulling cable with a wire rope to prevent the rope from twisting or unravelling.
We recently had a request from a customer regarding our 00505-030A locking swivel. This product is a locking line swivel, constructed with special bearings for supporting tensile load. The swivel is designed to ‘lock up’ when load is applied, and allow rotation again once pulling tension is relieved.
The question from our customer was: When does the swivel lock up? The answer is, famously: It depends. It really depends on your definition of ‘locking’, since the torque vs. load curve for this swivel is actually linear. In other words, the more tensile load applied to the swivel, the more torque it takes to rotate the swivel. This applies to the 00505A series of swivels in general.
For instance, our test results for the 00505-030A show that at 2000lbs line load, it takes 10ftlbs of torque to rotate the swivel. At 4000lbs load, the torque requirement doubles roughly to 20ftlbs. At the 5:1 SWL of 6000lbs, one would require 30 ft-lbs, and at the 3:1 SWL of 10,000lbs, 50 ft-lbs is required to rotate the swivel. So your desired locking value really depends on how hard you pull. In any case, relieving pulling tension on the swivel will allow the locking torque to also return to zero.
Don’t forget to use cable lubricant to reduce your pull load tension.