Gantry cranes are one of the most common types of industrial cranes. They are quite similar to bridge cranes in nature; the only significant difference between the two types is the movement of rubber-tyred gantry cranes relative to bridge cranes.
The important features of a gantry crane are briefly described in this section.
Main Girder
It forms the Crane’s primary structural system, along with the supports. Its objective is to provide a platform for the carriage-hoist unit’s movement as well as to support the efforts it receives. It can also hold the control cabin, numerous electromechanical systems, and maintenance access gateways.
It is made up of a large-scale metallic girder. These cranes’ main construction is mostly made up of box type girders made of steel sheets with a required dimension of 8 mm.
• Design of a gantry crane
• Gantry Crane Made of Aluminum
Basic Components of Gantry cranes:
- Support Legs
They are in charge of receiving and channelling the higher output by the beam to the earth. They can also accommodate the cockpit, electromechanical systems, and approach stairs, just like the beam.
- Trolley
It is the structure that supports and houses the elements that make up the upraise system for cranes with open winches, or it is the structure that supports and houses the hoist for cranes with this type of product. It can be constructed as a whole or in parts, depending on the size or weight.
Its shape, size, and weight are all varied since they are developed and designed to meet the specific requirements of each Crane, which vary depending on lift capacity and service features. The trolley is used to keep the hoist in place. It has an electromechanical group attached to it that permits it to travel along the beam.
- Technical Specifications
The end trucks for bridge translation must be composed of structural steel in the shape of a box and must be able to withstand all combined vertical, lateral, and torsion forces induced by live loads, dead loads, impact loads, accidental loads, and dynamic loads caused by crane operation.
The maximum permitted deformation caused by the dead weight, carriage weight, and 125% of the nominal static load in the bridge shall not exceed 1/8 of the clear.
In this deflection, the impact load should not be taken into account. The carriage must be powerful that is equal to the dead load’s deflection plus half of the live load’s deflection. Lifting points (lifting lugs, eye bolts, etc.) must be present on the vehicles.
- Crane hook
The hook and hoist rope is a machine that consists of two or more pulleys and a rope, cable, or chain that switches between multiple hazards. They allow you to raise a load with a force that is less than the weight that has to be moved.
The hoist is a mechanism that allows a load to be lifted vertically by employing the lift force created by the action of at least two pulleys. When the loads are light, the branches can be chains or steel cables.
Technical specifications:
The Crane’s primary hook can be of the twin peak type, made of forged steel and supported by ball or roller thrust bearings to allow full rotation around its vertical axis.
The auxiliary hook can have a single peak (standard) and have the same other properties as the main hook. The auxiliary hook will move along the outer bridge beam along the sidewalls and will be independent of the car’s movement.
A platform must be constructed for the maintenance of the auxiliary lift, which is accessible from the overhead Crane. A mechanical safe must be installed on both the main and auxiliary hooks. The appropriate tools for greasing the bearings of the pulley holder must be provided.
Mechanism of translation
Rails or pneumatic wheels are the most popular ways of translating gantry cranes. As a result, the supports are designed to support bogies or frames with electromechanically driven wheels.
Steel wire rope use:
The lifting cables must be designed and constructed specifically for crane service; flexible, self-lubricating, improved plough steel (tensile strength can be between 180 and 200 kg / mm2), 6 strands of 37 threads or 6 strands by 19 threads, with steel core, and the design and implementation must comply with quality standards.
The attempt produced by the rated load plus the weight of the rigging of the hooks in each of the connections must not exceed 20% of the last effort of the same material.
Conclusion:
The contractor must supply the proper grease for the cable; within this delivery, a sufficient quantity of grease must be evaluated for the bridge assembly, two further re-lubrications during the Crane’s operation process in the Central’s equipment assembly, and the Crane’s initial repair.
