12.3 Master Links, Rings and Swivels
Key Takeaways
Master-link capacity and hook fit are separate checks.
Intermediate links organize connections but do not inherently equalize legs.
Under-load swivel use requires explicit product approval.
Collect forces without crowding
Links and rings connect rigging components or collect several sling legs into a common upper connection. A master link receives the assembly’s combined load and must fit the hook and lower components. Its opening and bearing geometry matter independently of its tensile rating.
A link too small for the hook can ride toward the tip, wedge against the shank or prevent the hook’s latch from closing. A link large enough to admit many eyes can still create crowding, crossed loads or bending if the eyes do not seat correctly. Select the rated collector arrangement specified for the assembly rather than forcing all connections into the nearest ring.
Master-link subassemblies use intermediate links to organize multiple legs and provide room for proper bearing. They are common in three- or four-leg systems, but no universal rule requires one identical arrangement for every sling assembly. The manufacturer’s approved construction and rating control. Intermediate links do not automatically equalize lower-leg forces.
Identify the rating basis
A link can carry different arrangements with different capacity conditions. The sling material, number of legs, included angles and connected hardware influence its application. A manufacturer may rate a master link as part of a particular chain assembly rather than give an unrestricted capacity for any collection of components.
| Collector check | Purpose |
|---|---|
| Manufacturer and rating | Establishes the actual product and allowable use |
| Upper hook fit | Keeps load in the bowl with proper bearing |
| Lower component fit | Avoids crowding, crossing and binding |
| Included angles | Keeps forces within rated conditions |
| Complete assembly demand | Includes everything the collector carries |
The master link may carry payload plus lower rigging and a lifting device. An individual leg connection carries its own tension. Do not assume both demands are numerically identical. Trace the masses and forces through each level of the assembly.
Use compatible connectors
Connecting links for chain often have specific locking, pin or bushing arrangements. Install the correct components in the specified sequence. A connector that appears closed may still be incomplete if its locking pin is not fully installed. Do not replace parts with bolts, wire or a different manufacturer’s piece without approval.
Some connectors are intended for chain, some for textile slings, and some for wire-rope eyes. Contact width and bend geometry can limit the use of a steel fitting with a textile sling. The fitting’s WLL alone does not prove that it will not pinch or cut the sling.
Avoid joining eyes by an unapproved improvised arrangement. The resulting bend and contact can be different from either sling’s rated condition. Use appropriate rated hardware with the manufacturer’s specified geometry and capacity.
Swivels manage alignment only as designed
A swivel permits relative rotation in a connection under its specified conditions. Some products are intended for alignment without load; others use bearings designed for rotation under load. Read the actual product instructions. A swiveling appearance does not establish under-load rotation permission.
A swivel also interacts with rope construction. Certain rope systems restrict swivels because rotation can affect strand balance or core behavior. The rope and equipment manufacturer instructions must agree with the proposed connection. Do not insert a swivel simply because a load tends to spin.
An under-load swivel does not eliminate the need to control payload rotation. Wind, asymmetric contact or rope torque can still create movement. The handling plan must provide appropriate orientation control and safe personnel positions.
Demand example
A master link collects two legs carrying a 20,000-lb payload and 800 lb of lower device and rigging weight. In the simplified static model, its vertical resultant demand is 20,800 lb. Each inclined lower leg can have a tension that is greater than half that total. Selecting a master link based on one leg’s reaction or selecting each leg based on the master link’s vertical load would confuse the force paths.
Inspect and maintain the connection
Check markings, wear, cracks, deformation, corrosion, heat damage and locking parts under applicable B30.26 and manufacturer criteria. A distorted ring can impose unintended bearing even if its remaining cross section appears large. Missing pins or incomplete locks require removal from use until properly resolved.
Do not heat, weld or bend a link to change fit. Altering its geometry can change strength and invalidate the assembly rating. A component that does not fit should prompt compatible selection, not field reshaping.
During take-up, verify the collected legs settle into their intended positions. Do not reach into a closing collector to straighten a crossed eye while force develops. Stop and unload through the planned process before correcting the arrangement. After use, keep related components identifiable and prevent loose connectors from being mistaken for approved substitutes.
The exam trap is treating a collector as a magic capacity multiplier. It organizes and transmits forces; it does not create additional sling strength or guarantee equal lower-leg loading. Capacity and geometry must be checked at every interface.
Sources: CCO B30.26 and reference booklet resources, Crosby connector information.
A swivel turns freely while unloaded. Does that establish permission to rotate it under load?
Yes; unloaded freedom proves bearing capacity
Yes if the load is balanced
Yes if its paint matches the master link
No; the actual product must be approved for under-load rotation
Sections you finish are checked off in the contents.