Knuckle-boom crane
A truck-mounted crane with an articulated, folding boom that bends at a knuckle joint, used for unloading, material handling, and precision placement in confined spaces.
A knuckle-boom crane (also called an articulated crane, loader crane, or knuckleboom) is a hydraulically actuated arm with a folding "elbow" or knuckle joint partway along its length. The folding action lets the crane operate in tight spaces — it can reach under obstacles and behind the truck cab in ways a telescopic boom cannot. Most knuckle-boom cranes mount on truck chassis behind the cab, though some are fitted to barges, fixed installations, and small trailers.
Knuckle-booms are the standard tool for medium-duty material handling: unloading building materials and prefab units, placing roof trusses, handling timber and steel, marine cargo work, and tree care. Capacities typically range from 1-tonne machines on light trucks up to 100+ tonne-metre machines on heavy chassis. (Knuckle-boom capacity is usually quoted in tonne-metres rather than tonnes — see the load-chart entry.)
The European market is dominated by HIAB, Palfinger, Fassi, Effer, and PM. The bigger machines often have a fly jib (a third boom section) for extra reach and remote-controlled hydraulic functions so the operator can stand near the load. Many are now sold with stability monitoring that automatically de-rates capacity based on actual outrigger spread and slewing position.
Key spec comparisons: lifting moment in tonne-metres at boom length, number of hydraulic boom sections, presence of a fly jib, maximum hydraulic outreach, and remote control type (cable, radio, or both).