A gantry crane is an overhead crane with a structure similar to that of a bridge. The bridge contains a trolley that uses the standard hoisting mechanism for the movement of goods in various directions. Unlike the conventional overhead cranes, gantry cranes are wheeled on rails. This means that it is a mobile structure that can be carried from one place to another quite conveniently.
The structural composition of a gantry crane includes the main work space at the top, also known as the gantry. There are a hoist and a trolley which lift and move the goods. The hoist and trolley are attached to a beam that runs along the median line of the gantry. This gives it a firm structure which can efficiently handle heavy weights.
Gantry cranes are sometimes also known as a portal crane. The term portal is used to describe the work space or portal of the crane. Since gantry cranes are mobile, they are generally used in places where the goods cannot be brought to the crane, like in the case of an overhead crane. Amidst gantry cranes as well, there is a further classification.
There are various types of gantry cranes.
Full Gantry Crane:
In the case of the full gantry cranes, the load carrying part of the crane lies below the gantry and is supported firmly by a beam. A complex network of cables and attachments also staunchly supports the structure. Due to this firm structural composition, full gantry cranes can counter attack the torque from the load. Due to such a mechanism, extremely heavy weights like ship engines can be carried using a full gantry crane. The world’s largest gantry crane, available in the port city of Yantai of China, is capable of carrying 22,000 tonnes.
Rubber Tired Gantry Crane:
As the name suggests, these cranes are wheeled with rubber tires. Due to such a structure, these gantry cranes don’t need a rail for mobility. These are usually smaller than the other gantry cranes which enable the rubber tires to handle their load. When an easily moveable crane is required that can navigate through multiple rails and can be conveniently carried, rubber tired gantry cranes are used. Rubber tired gantry cranes can smoothly lift heavy loads to good heights. These are mostly used in the work areas where there is a considerable size restriction and the maximum space utilisation is required vertically.
Workstation Gantry Crane
Small work stations or medium-sized factories use workstation gantry cranes. These cranes are smaller in size and can conveniently lift lighter goods. When unloaded, these cranes can be moved. However, when they are loaded with goods, they remain stationary. The hoisting mechanism in the workstation gantry cranes is assisted by wire rope hoists or in some cases chain hoists with lower capacity.
All these different types of gantry cranes are used for different purposes. The choice of an effective gantry crane is done based on the work station area and the utility of the crane.