Rail Container Gantry Cranes

Rail container gantry cranes are a form of gantry cranes mounted on rails to aid movement while hoisting heavy items from one position to another. The other form of movement can be on rubber tyres. The first design of a rail container gantry crane appeared in the year 1960. It was designed by Paceco Corporation and referred to as a “Portainer”, coined from the words “port” and “container”. The major loads hoisted by this type of cranes are cargo containers, usually from ship to shore or vice-versa. Thus, they are also referred to as ship to shore cranes.

Operation Of Rail Container Gantry Cranes

Using either electrical AC or diesel engine powered DC as the power source, the trolley in rail container gantry cranes run along rails wile hoisting loads. These rails are located on the top of the boom and girder or at their sides and serve as the support end for moving the hoisted load.

Rail container gantry cranes are best suited for inter-modal container terminals where multiple containers need to be moved from one holding area to another. This can include ship to shore, truck to train, ship to truck, ship to train and vice versa. For these operations, the most important consideration is movement of the container to its desired location effectively and not the speed at which it is moved. One big advantage of rail container gantry cranes is that it allows for better land usage at a shipyard or port and also reduces possibility of ground accidents. This is so since movements by multiple mobile cranes has been eliminated. Also, it increases available stacking area for containers. When offloading containers from ships, the rail container gantry cranes usually straddle the ship, allowing for lifting and moving massive objects over the ship without problems.

For maximum effectiveness at a container terminal, rail container gantry cranes are built with a supporting framework that can manoeuvre across the length of the quay. This framework supports a platform, also known as a “spreader”, allowing the spreader to be lowered to latch onto a container and move it to and from a specific location at the quay. Containers are usually picked one at a time, but some newer rail container gantry cranes have the capacity to pick up four (4) containers at a go.

Two major types of rail container gantry cranes in operation today are the high profile and low profile variants. The low profile variants are most suitable for use when container terminals are situated close to airports, where the high profile type may obstruct the flight path of a plane. In terms of size, rail container gantry cranes are rated with reference to the Panama Canal, especially when the cranes are welded on to and travel with the ship.

We can have a “Panamax”, “Post Panamax” and “Super Post Panamax”. In this light, a “Panamax” crane is one capable of fully loading and off-loading a container ship that can pass through the Panama Canal, while the “Post Panamax” does same for ships too wide to pass through the Panama Canal. The largest, which is the “Super Post Panamax”, is about twice the size and weight of the “Post Panamax.”

How Do Gantry Cranes Work?

In its simplest form, a gantry crane is a member of the fixed family of cranes, with the other main family being the mobile variant. Similar crane types which are members of the fixed family include the overhead crane, jib crane, loader crane etc. A gantry crane, also called a portal crane is a type of crane that has a vertical support on one end, and moves horizontally at the other end, either on rail tracks or on rubber tyres. Usually, gantry cranes lift large or small objects by the means of a hoist which is fitted in a trolley and allowed to move horizontally across an area over which it picks and drops items. Gantry cranes are found in most port locations around the world, as they are used for lifting heavy objects around ships, which is a major advantage for gantry cranes in the shipping and heavy duty industries.

The major types of gantry cranes in use today include the container gantry crane, rail mounted or Electrical Overhead Travelling (EOT) gantry crane and the workstation gantry crane, mobile gantry crane.

Applications Of The Gantry Crane

As earlier noted, gantry cranes are utilized mainly in heavy industries, with its largest types being found in ship-building and port locations around the world. This is because they are specifically designed for lifting very large and heavy objects. At their prime locations, these objects include containers and ship-engines. Smaller gantry cranes can be found in car workshops and are used for lifting engines and their components in and out of cars. These variants are usually mobile units or free standing gantry cranes.

Power for operation of gantry cranes is usually derived from two main sources via diesel engine power generators and electrical power. The diesel powered generators can be found at the top of the crane and emits Direct Current (DC) while the electrical power source is usually located at the dock. This is also referred to as shore power and emits Alternating Current (AC).

Gantry cranes can be classified either based on their operational capability and size or physical mode of operation. The most advanced of the pack is the automated gantry crane, also referred to as the Stacker. It is usually unmanned and controlled from a remote operations center. This is used when volumes of large loads, especially containers are to be moved between two holding bays, e.g. from ship to train or truck to ship and vice versa. In terms of size, the rail container gantry cranes are the largest available anywhere in the world. Two famous gantry cranes nicknamed Samson and Goliath, built in 1974 and 1969 respectively are one of the largest in the world today. In combination, they have a lifting capacity of over 1,600 tonnes at heights up to 70metres. They currently reside and execute lifting assignments in the largest dry dock in the world at Belfast.

The hoist, that is, load lifter on gantry cranes can either be located in a fixed machinery enclosure or on a trolley. Trolley hoist systems usually run horizontally along rails and can be fitted either on a single beam or on two beams, that is, a mono girder and twin girder respectively. When gantry cranes run on rubber tyres, there is no need for a rail system, thus reducing cost and earth impact.