Gantry cranes are essential lifting equipment used across various industries, including shipbuilding, construction, logisctics and manufacturing. Their robust design and versatile functionality make them indispensable for handling heavy loads with precision and efficiency. In this article, we will mainly introduce the structure of gantry cranes, explaining their key components and how they work together to deliver optimal performance.
Key Components of General Gantry Crane
Bridge (Girder)
The bridge, also known as the girder, is the primary horizontal beam that spans the width of the crane. It is responsible for supporting the hoist and the load it carries. Gantry cranes can have a single girder or a double girder, depending on the lifting requirements. Single girder gantry cranes are typically used for lighter loads, while double girder gantry cranes are designed for heavier capacities and longer spans.
- The material of the main beam is Q235-B, and the minimum plate thickness is not less than 6mm. The main beam can extend out of the legs to one or both sides to form a cantilever, thus increasing the operation range of the crane. The length of the cantilever is generally less than or equal to 1/3 of the span length.
- The end beam is a box-shaped structure, and the connection between the end beam and the main beam is a rigid connection. In order to facilitate transportation, the main beam and end beam are connected by high-strength bolts, and each connecting plate is positioned by reamed bolts.
Legs
The legs are vertical structures that support the bridge and connect it to the ground or to rails. These legs are crucial for maintaining the stability and balance of the lifting equipment.
The leg adopts a trapezoidal cross-section structure with a large upper and a small lower section. The upper flange of the leg and the main beam flange support are connected by high-strength bolts, and the lower flange of the leg and the upper connecting flange of the lower cross beam are connected by high-strength bolts.
Hoist and Trolley
The hoist is the lifting mechanism of the gantry crane. It comprises a motor, a drum or chain, and a hook or lifting attachment. The hoist moves along the length of the bridge, lifting and lowering loads with precision. The hoisting mechanism adopts a series resistance speed control system with stable braking, small impact and accurate hook positioning, which not only improves the production efficiency, but also greatly extends the service life of the parts of the hoisting mechanism.
The trolley is a mechanism that carries the hoist along the bridge. It moves horizontally, allowing the crane to position the load accurately.
Lifting Attachments
Gantry cranes can be equipped with different lifting attachments to handle a variety of loads, including:
- Hook lifting attachments for almost any type of gantry crane.
- Beam lifting clamps, concrete beam spreaders, adjustable beam sling and hook systems, or other lifting attachments for concrete beam gantry crane.
- Grab buckets for grab gantry crane.
- Electromagnetic or permanent magnets for electromagnetic gantry crane.
Crane Running Mechanism
The crane running mechanism is a critical structure of gantry cranes, responsible for facilitating their movement along a predetermined path. This mechanism typically includes a set of wheels or rollers, driven by electric motors, that enable the crane to traverse along rails or tracks. It consists of a motor, transmission system, and wheels that ensure smooth and stable motion. The wheels can be rubber-tyred for mobility in rubber tyred cranes or steel wheels for rail-mounted gantry cranes. Additionally, the running mechanism incorporates braking systems for safety and control, allowing precise positioning of the crane during operations. This integrated system ensures the crane can efficiently and accurately move heavy loads within its operational area.
Runway (Rails)
The runway is a set of tracks on which the crane travels. These rails can be mounted on the ground or elevated on a structure, depending on the operational requirements. The runway ensures smooth and precise movement of the crane along the designated path.
Control System
The control system is the interface through which the operator controls the crane’s movements. It can be a simple pendant control or a sophisticated radio remote control and cabin control, offering various levels of functionality and safety features. The control systems often include advanced features such as anti-sway technology, load monitoring, and automated positioning.
Power Supply
Gantry cranes primarily operate using direct electrical power supplied through systems such as cable reels or festoon systems. In a cable reel system, a cable winds and unwinds as the crane moves, maintaining a constant connection to the power source. Alternatively, festoon systems use trolleys that support and guide the power cables along a track, ensuring smooth and uninterrupted power delivery. These methods provide reliable and efficient power to the crane’s motors, controls, and lifting mechanisms, enabling precise and robust operation in various industrial environments.
Structures of Different Types of Gantry Cranes
Among the various types of gantry cranes, double girder, rubber tyred, and rail mounted types are widely used due to their distinct structures and operational advantages. Here we compare the structures of these three types of gantry cranes to help you understand their unique features and benefits.
Double Girder Gantry Crane Structure
The double girder gantry cranes feature two horizontal beams (girders) that span the width of the crane. These girders are supported by robust vertical legs, which are anchored to the ground or move along rails. The hoist and trolley run on rails mounted on top of the two girders, providing stability and allowing for the lifting and horizontal movement of loads.
Key Components:
- Girders: Two horizontal beams providing strong support for the hoist and trolley.
- Legs: Vertical supports that transfer the load to the ground or rails.
- Hoist: Lifting mechanism that moves along the girders.
- Trolley: Carries the hoist and moves horizontally on the girders.
- Rails: Fixed on the ground to guide the crane’s movement.
Rubber Tyred Gantry Crane Structure
Rubber tyred cranes are characterized by their mobility, provided by wheels instead of being fixed to rails. The structure includes a horizontal beam supported by vertical legs equipped with rubber tires. These rubber tyre gantry cranes are designed for flexibility, allowing them to move freely within a designated area.
Key Components:
- Girder: A single or double horizontal beam that supports the hoist.
- Legs: Vertical supports mounted on rubber tires for mobility.
- Hoist: Lifting mechanism that moves along the girder.
- Trolley: Carries the hoist and moves horizontally on the girder.
- Wheels: Rubber tires that enable the crane to move without rails.
- Power Source: Usually powered by electric, or hydraulic systems.
Rail Mounted Gantry Crane Structure
Rail mounted cranes are fixed on rails, providing precise movement along a straight path. The structure includes a horizontal girder supported by vertical legs, similar to double girder cranes, but with wheels designed to run on rails. These cranes are highly stable and can handle heavy loads with precision.
Key Components:
- Girder: Horizontal beam supporting the hoist and trolley.
- Legs: Vertical supports with wheels designed to run on rails.
- Hoist: Lifting mechanism that moves along the girder.
- Trolley: Carries the hoist and moves horizontally on the girder.
- Rails: Fixed tracks on the ground that guide the crane’s movement.
Comparison of Different Gantry Crane Structures
Mobility:
- Double Girder Gantry Cranes: Generally fixed on rails; limited mobility.
- Rubber Tyred Gantry Cranes: Highly mobile with rubber tires, ideal for flexible operations.
- Rail Mounted Gantry Cranes: Fixed on rails, providing precise but restricted movement along the rail path.
Lifting Capacity:
- Double Girder Cranes: High lifting capacity, suitable for heavy-duty applications.
- Rubber Tyred Cranes: Moderate to high lifting capacity, designed for flexible industrial lifting applications.
- Rail Mounted Cranes: High lifting capacity, ideal for heavy and repetitive lifting tasks.
Operational Environment:
- Double Girder Cranes: Suitable for indoor and outdoor environments with fixed operational areas.
- Rubber Tyred Cranes: Suitable for indoor and outdoor, flexible operational areas.
- RMG Cranes: Perfect for structured environments with fixed rail paths like ports and rail yards.
Conclusion
Understanding the structure of gantry cranes is crucial for selecting the right crane for your needs and ensuring safe and efficient operation. As a leading crane manufacturer, we offer a wide range of high-quality cranes designed to meet the diverse demands of our clients. Whether you need a large gantry crane for heavy-duty applications or a rubber tyred gantry crane for more flexible use, our team of experts is here to help you find the perfect solution. Contact us today to learn more about our products and services.
