This terminal section of a crane boom or jib houses the main sheaves, wire rope guides, and dead-end anchors for the hoist system. It must withstand severe bending moments and torsional loads from the swinging payload. Inspectors pay close attention to this area for fatigue cracking and sheave pin wear due to the constant dynamic loading.
Heard on the job
The rigger noticed a frayed wire rope right where it passes over the main sheave at the jibhead.