Overhead Crane image courtesy of Brehob Corporation.

At a time when Ireland’s troubles were raging, there came a great announcement from one of Northern Ireland’s largest employers, Harland & Wolff. They were going to build two enormous gantry cranes to further their reputation and reach as one of the largest shipbuilders in the world. The first was completed in 1969 and the second in 1974. Named after biblical figures symbolizing grand strength, the first was called Goliath and the second Samson. Although things did not bode so well for these two fellows, the twin shipbuilding gantry cranes still stand at Queen’s Island in Belfast, Northern Ireland, and are considered landmark structures of the city.

Gantry cranes come in all sizes, but are most noticeably used to move very heavy loads, especially extremely large ones like in shipyards, bridge building and industrial installations. There are special versions of gantry cranes called container cranes, or Portainer cranes, that load and unload ship-borne containers at a port. Gantry cranes can be large enough for the movement of shipping crates across storage yards, and they can be small enough to suit small-scale, indoor industrial processes.

A gantry system is supported by a stable structural framework. The hook and hoist assembly is fitted in a trolley for horizontal movement along rails across a single beam (mono or single-girder) or two beams (twin or double-girder). Relying on the linear and vertical motion powered by drives and motor systems, the hoist can lower, lift and move the load across the beams. The frame consists of equally balanced support beams with gantry rails that run perpendicular to the trolley beam(s). Therefore, the gantry rails and the trolley beams are connected at right angles to each other, creating the capabilities of side-to-side and length-to-length motion.