jibhead

The jibhead is the structural assembly at the free end of a crane jib, where the hoist rope attaches and loads are picked up. It carries the full working load of the crane and must withstand bending, shear, and torsional stress as the jib swings and the load moves beneath it. In mining operations, where jibs are mounted on gantries or pedestal cranes over loading bays and stockpiles, the jibhead takes repeated shock loads from bucket grabs and magnet systems.

Construction varies with load class and jib design. A simple jibhead on a small capacity jib may be a welded steel box section with a clevis or trunnion pin for rope attachment. Larger mining jibs use cast steel jibheads with integral load sheaves; the hoist rope runs through a block that rotates on bearings mounted in the head casting. High-cycle operations demand jibheads with needle roller bearings or sealed ball bearings to manage sideways thrust from skewed loads.

Failure modes and maintenance

Fatigue cracking initiates at the stress concentration where the jibhead transitions to the main jib tube. Loads that jerk sideways instead of lifting vertically, caused by uneven grab closure or magnetic pull, magnify bending stresses here. Regular visual inspection under good light, especially around welds and the rope attachment eye, is critical. Any sign of paint peeling, rust bloom, or linear cracks means the jibhead is yielding and requires ultrasonic or magnetic particle testing before return to service.

Wear in the rope attachment pins and sheave bearings is progressive and cumulative. Grooved rope wears the sheave grooves; worn grooves then abrade the rope faster. A jibhead sheave worn to less than its original diameter reduces mechanical advantage slightly, but the real danger is uneven rope tension between parts of a multi-part rope, which pulls the jibhead sideways under load. Replaceable jibheads on modern cranes are bolted on for this reason; older cranes with welded heads require in-situ machining or full jib replacement.

The term jibhead appears mainly in British and Commonwealth mining and quarrying work; American equipment spec sheets more often say jib end, jib tip, or simply refer to the hoist block assembly. In European standards, jibkop (Dutch) and similar terms are used. The word aligns with maritime jib terminology, where a jib is any forward-pointing spar; here it just means the reach of the arm itself.