Gantry crane
An overhead lifting machine on legs that run along ground-level rails, used in shipyards, container terminals, warehouses, and heavy-industry yards.
A gantry crane (also called a portal crane or rail-mounted gantry, RMG) is a lifting system that hangs the trolley and hoist from a horizontal bridge spanning between vertical legs. The legs run on rails or rubber tyres at ground level, so the entire crane bridge travels along a rectangular work area. This contrasts with overhead bridge cranes, where the bridge runs on rails fixed to the inside of a building.
Common gantry-crane categories include rail-mounted gantries (RMGs) and rubber-tyred gantries (RTGs) in container terminals; goliath cranes in shipyards (some of the largest gantries in the world, with spans of 100+ metres and capacities of 1,500+ tonnes); workshop and warehouse gantries (semi-gantry, double-girder, single-girder) for industrial assembly; and portable A-frame gantries for light workshop use.
Capacities range from sub-tonne workshop gantries to 1,500+ tonne shipyard goliaths. The biggest manufacturers in the heavy-industry segment are Konecranes, Liebherr (LCC mobile harbour cranes), Kalmar, ZPMC, and Mammoet (mobile gantry systems for heavy transport).
When evaluating a used gantry, the operational specs that matter most are span (rail-to-rail distance), lift height, capacity at full span and at reduced radius, rail vs rubber-tyred travel, and the host structure's compatibility (rail gauge, foundation loads, electrical supply).