Gantry cranes are essential lifting systems used across ports, shipyards, manufacturing facilities, and construction sites. Among their structural classifications, single girder and double girder designs are the most common. Understanding the differences between these two structures is crucial when selecting the right crane for specific operational, budget, and space requirements.

This article examines the structural composition, advantages, limitations, and application suitability of single and double girder gantry crane for sale to help you make an informed decision.

1. Structural Overview

Single Girder Gantry Crane

A single girder gantry crane has one horizontal main beam (girder) supported by legs on either side, traveling on rails or wheels.

Main Components: One girder, two legs, trolley/hoist, end carriages, and travel mechanism.

Trolley Position: The hoist trolley runs along the bottom flange of the single girder (under-running) or on top of it (top-running).

Design Simplicity: Lighter structure with fewer components compared to double girder designs.

Double Girder Gantry Crane

A double girder gantry crane features two parallel horizontal main beams connected by cross bracing, supported by legs.

Main Components: Two girders, two legs, end carriages, trolley, hoist, and travel mechanisms.

Trolley Position: The trolley travels on rails mounted on top of both girders.

Structural Robustness: Capable of supporting higher loads and longer spans.

2. Load Capacity and Span

Single Girder:

Typical capacity: Up to 20–30 tons (though heavy-duty designs can exceed this).

Suitable for shorter spans, usually up to 20–25 meters.

Designed for lighter lifting duties and moderate operational cycles.

Double Girder:

Typical capacity: 20 tons to over 500 tons.

Capable of handling long spans (30 meters or more).

Ideal for heavy-duty operations and continuous use.

3. Structural Strength and Stability

Single Girder:

Less structural mass means lower dead weight and reduced foundation requirements.

More flexible under load, which can be beneficial for certain applications but may limit performance in high-precision lifting.

Double Girder:

Higher structural rigidity due to the twin-girder arrangement.

Better load distribution across the crane structure, reducing stress on individual components.

Suitable for high-precision lifts and operations requiring minimal deflection.

4. Lifting Height

Single Girder:

Lower lifting height since the hoist is usually mounted beneath the girder.

May not be suitable for applications requiring maximum hook height.

Double Girder:

Greater lifting height as the hoist can be mounted between the girders.

Provides additional headroom, which is crucial in shipbuilding, steel fabrication, and container handling.

5. Cost Considerations

Single Girder:

More cost-effective in terms of manufacturing, transportation, and installation.

Lower maintenance costs due to fewer structural components.

Best suited for light to moderate lifting applications.

Double Girder:

Higher initial investment due to more materials and engineering complexity.

Increased maintenance requirements but delivers greater long-term versatility and durability.

More cost-efficient over time for heavy-duty, high-cycle applications.

6. Installation and Maintenance

Single Girder:

Faster and easier installation due to its lighter and simpler design.

Easier to relocate for temporary projects.

Maintenance is generally simpler.

Double Girder:

More complex installation requiring precise alignment and stronger foundations.

Higher maintenance requirements due to additional components but offers greater structural lifespan.

7. Applications

Single Girder Applications

Small manufacturing workshops

Assembly lines

Light fabrication shops

Small warehouses

Outdoor yards with moderate lifting needs

Shipyards and ports

Heavy manufacturing plants

Steel fabrication facilities

Precast concrete yards

Container handling terminals

9. Choosing Between Single and Double Girder Gantry Cranes

When deciding between a single or double girder structure, consider:

Required lifting capacity – If exceeding 20–30 tons regularly, a double girder is advisable.

Span length – Long spans favor double girders for stability and safety.

Lifting height requirements – High hook positions typically require double girder designs.

Budget constraints – Single girder gantry cranes are more affordable but may have performance limitations.

Frequency of use – High-cycle operations benefit from the durability of double girders.

Space availability – Single girders require less space and lighter foundations.

Conclusion

Both single girder and double girder gantry cranes serve critical roles in material handling, but their structures are optimized for different operational demands. Single girders provide a lighter, cost-effective solution for moderate lifting, while double girders deliver superior strength, height, and capacity for heavy-duty applications. By carefully evaluating load requirements, lifting height, span, and budget, operators can select the most efficient crane structure for their needs - ensuring safety, productivity, and long-term reliability.