The luffing jib (also called luffing boom) is a tower crane boom that can be tilted up and down hydraulically or by cable (luffing). Unlike the horizontal trolley boom, where the trolley moves along the boom, the luffing jib changes its angle of inclination to vary the outreach — positioned almost vertically when minimal slewing radius is required.
The main advantage: minimal slewing radius when the boom is tilted upward. On construction sites with multiple cranes (city centers, high-rise construction), luffing jibs prevent collisions with adjacent cranes. In windy conditions, the boom is tilted upward instead of freely rotating as with a trolley boom. Proximity to airports and airspace restrictions also often necessitate luffing jibs.
Disadvantage: Luffing is slower than trolley movement, and load capacity changes with the boom angle — steeper angle = shorter outreach = higher load capacity. Liebherr (HC-L series), Potain (MDT-CCS), Wolffkran, and Jaso offer top-slewing cranes with luffing jibs. In Asia and the Middle East, luffing jib cranes are significantly more widespread than in Europe.
