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.