7.1 Gantry Cranes
7.1 Cargo Handling Gear - Gantry Cranes
Cargo handling on merchant vessels requires diverse equipment to efficiently and safely load, unload, and maneuver cargo of various shapes, sizes, and weights.
Gantry cranes offer versatility and lifting capacity. Their fixed structure provides exceptional stability for lifting project cargo, while the mobility of the trolley and jib allows for precise positioning and secure attachment.
Fixed structure: Gantry cranes possess a fixed, gantry structure. This double portal design features two upright supports spanning a horizontal beam, creating a bridge-like configuration.
Mobility through Trolleys and Jibs: While the gantry itself remains stationary, its functionality is enhanced by a movable cable trolley with jib. The trolley travels horizontally along the beam, allowing for precise positioning over the cargo hold.
Attached to the trolley, the jib, a projecting arm, extends further outwards, increasing the crane's span length. This combined mobility of trolley and jib enables the gantry crane to effectively service a wider area within the cargo hold.
Applications and Advantages: Gantry cranes excel in handling specific cargo types. They are particularly well-suited for project cargo, long and heavy objects that may not be readily maneuvered with conventional shipboard cranes.
The gantry's fixed structure provides superior stability when lifting these cumbersome items. Additionally, the ability to precisely position the trolley and jib facilitates the secure attachment of four-point suspension slings to the cargo, ensuring balanced and controlled lifting.
Operational Considerations: The efficient operation of gantry cranes hinges on several factors. Trim, the longitudinal inclination of the vessel, must be carefully monitored to maintain a level working platform for the crane.
Additionally, the maximum lifting capacity of the crane needs to be strictly adhered to, and the cargo weight must be evenly distributed across the four-point suspension to prevent imbalances. Furthermore, the movement of the trolley along the beam is often guided by rails, ensuring smooth and controlled travel.