A rubber tyred gantry crane, also known as a RTG crane or transtainer, is a mobile gantry crane used for stacking intermodal cargo containers within the stacking areas of a shipping container terminal.
Although from a side view, a RTG crane and a straddle carrier look strikingly similar, however the top of a RTG features a movable crane and runs on rubber-tyres, instead of steel rails.
The first electrified rubber-tyred gantry crane (ERTG) was unveiled by The Georgia Ports Authority (GPA) in the United States, in December 2012. The new technology reduces fuel consumption by an estimated 95 percent.
A ship-to-shore (STS) crane, also known as a container crane, is a type of large dockside gantry crane found at many of the world’s container terminals. STS cranes are used for loading and unloading container cargo from shipping container vessels.
This type of container crane is generally classified by its lifting capacity, and the size of the container ships it can load/unload.
At the moment there are 3 common STS crane classifications:
Panamax: This crane can load and unload containers from a container vessel capable of passing through the Panama Canal – approximately 12 to 13 containers wide.
Post Panamax: These cranes can accommodate a container ship too wide to pass through the Panama Canal – approximately 18 containers wide.
Super-Post Panamax: The largest of the modern container cranes are classified for use on vessels with 22 or more containers wide.
A ship-to-shore rail mounted gantry crane (RMG) is a specialized version of the gantry crane. In this application, the horizontal gantry rails and their supporting beam are cantilevered out from between frame uprights, which have been spaced to suit the length of a standard freight container. This is done so that the beam supporting the rails projects over a quayside and over the width of an adjacent ship, allowing the hoist to lift shipping containers from the quay and move out along the rails to place the containers on the ship. The uprights have wheels which run in tracks allowing the crane to move along the quay to position the containers at any point on the length of the ship.
The first versions of these ship-to-shore rail mounted gantry cranes were designed and manufactured by Paceco Corporation. They were first known as Portainers and became so popular that the term Portainer is commonly used as a generic term to refer to all ship-to-shore rail mounted gantry cranes.
Aside from their applications in the shipping industry, rail mounted gantry cranes (RMG) are also commonly found in factory applications such as steel yards, paper mills or locomotive repair shops. Carrying capacities of the RMGs range from 2 to 200 tons, and in rare circumstances, even greater. Most are electrically powered.