What Is a Double Girder Overhead Crane? How Does It Differ from a Single Girder Overhead Crane?

Ⅰ Definition:

A double girder overhead crane is a type of bridge crane designed with two main girders and end beams, forming a “bridge” structure that spans across the upper space of workshops, warehouses, and other industrial buildings. It moves longitudinally along the rails through the crane travelling mechanism, while the trolley runs transversely on the main girders. Together with the hoisting mechanism, this enables the crane to perform three-dimensional lifting and material handling.

The rated lifting capacity of a double girder overhead crane typically ranges from 5 tons to 500 tons, with spans exceeding 35 meters, making it an indispensable lifting solution for large-scale industrial facilities.

Ⅱ Core Structure and Working Principle of a Double Girder Overhead Crane

1. Key Structural Components

Metal Structure：

• Main Girder: Usually designed as a box girder (welded from steel plates) or a truss girder, the main girder bears the entire load. Its cross-section is typically rectangular or I-shaped.
• End Beam: Connects the two main girders, with crane wheels mounted at both ends to enable the longitudinal movement of the crane along the runway rails.

Hoisting Mechanism：

• Consists of an electric motor, reducer, drum, wire rope, and hook block. The motor drives the drum to rotate, winding or unwinding the wire rope to lift or lower the load.

A double girder overhead crane is often equipped with both main and auxiliary hoisting mechanisms (e.g., 50/10 tons, where the main hook is 50 tons and the auxiliary hook is 10 tons) to meet different lifting requirements.

Travelling Mechanism

• Crane Travelling Mechanism: Composed of a motor, reducer, coupling, and wheel sets, it drives the bridge frame to move longitudinally along the crane rails.
• Trolley Travelling Mechanism: Installed on top of the main girders, it enables the trolley to travel transversely along the girder, achieving horizontal displacement.

Electrical System

• Includes control cabinets, operator’s console, cable sliding lines, frequency inverters, and safety devices. It controls start, stop, speed regulation, and safety protection of each mechanism.

Some advanced models are equipped with PLC-based intelligent control systems for enhanced automation.

2. Working Principle

The operator issues commands through the control console, which are received by the electrical system. The system then activates the corresponding motors. After torque is increased through the reducer, the motors drive the drum rotation or wheel movement, enabling the lifting, lowering, and travelling actions of the crane.

Ⅲ Classification of Double Girder Overhead Cranes

Ⅳ Advantages of Double Girder Overhead Cranes

1.High Load Capacity
Capable of lifting loads ranging from tens to hundreds of tons, a double girder overhead crane meets the requirements of large-scale equipment installation and heavy-duty material handling.

2.Wide Working Range
The crane covers the entire workshop area, and with extended rails, its operating range can be expanded to multiple factory buildings.

3.Strong Stability
With high structural rigidity, the double girder design provides excellent resistance to wind loads and vibrations, making it suitable for lifting and positioning precision equipment.

4.Multi-Mechanism Coordination
Equipped with both main and auxiliary hooks, as well as dual-speed control, the crane can adapt to complex lifting processes such as turning, alignment, or assembly of oversized components.

Ⅴ Comparison Between Double Girder Overhead Cranes and Single Girder Overhead Cranes

6. How to Select the Right Double Girder Overhead Crane?

Before selecting a double girder overhead crane, it is essential to carefully analyze and define your operational requirements:

1.Lifting Capacity (Tonnage)

• Determine the capacity based on the maximum weight of the loads handled in daily operations. It is recommended to reserve an additional 10%–20% margin.
  For example: if the maximum load is 5 tons, a crane with around 6 tons of lifting capacity is advisable.
• Note: The lifting capacity also includes the weight of lifting devices (such as hooks, electromagnetic lifters, or grabs), which should be calculated in advance.

2.Span and Lifting Height

• Span:The horizontal distance between crane runways. It must match the span of the workshop (measured by the column spacing or runway beam distance).
• Lifting Height:The maximum vertical distance required for lifting loads. Factors such as workshop height, stacking height, and ground clearance should be considered.
  Example: a clearance of 1–2 meters from the workshop ceiling should be reserved for safety.

3.Working Environment and Conditions

• Ambient Temperature:Standard operating conditions range from –20°C to +40°C. For high- or low-temperature environments, special materials or configurations are required.
• Duty Class:Classified from A1 to A8 according to operating frequency and load conditions.
• Explosion-proof / Anti-corrosion Requirements:For chemical plants or dusty environments, explosion-proof or corrosion-resistant cranes should be selected.

4.Operating Speed and Control Mode

• Hoisting Speed:Low speed for heavy loads, high speed for no-load operations. Select based on efficiency needs.
• Travelling Speed:The crane (long travel) and trolley (cross travel) typically operate at 40–80 m/min. Variable frequency drives can be selected for precision handling.
• Control Mode:Options include pendant control, wireless remote control, or operator cabin control (a cabin is recommended for high-altitude or intensive operations).

Additional Considerations for Selecting a Manufacturer

1.Qualification and Certification

• Business license and production permits for lifting equipment.
• Quality management system certifications and environmental management certifications.

2.Production Capacity

• Factory scale and production facilities.
• Advanced processing equipment and inspection procedures.

3.Project References and Reputation

• Case studies from similar industries.
• Customer feedback and user evaluations.

HSCRANE holds a complete set of manufacturing qualifications, including the Special Equipment Manufacturing License, ISO 9001 Quality Management System Certification, and ISO 14001 Environmental Management System Certification, ensuring that every overhead crane complies with national and international standards.

With modern workshops and advanced processing equipment, combined with a strict quality inspection process, we maintain full control from raw materials to finished products, guaranteeing high precision and long service life for each crane.

Our solutions have been successfully applied across a wide range of industries, including ports, mining, and power plants, earning strong recognition in the market. Customer feedback highlights: “Efficient and reliable performance, worry-free after-sales service!”

At HSCRANE, we believe that trust comes from professionalism, and quality builds the future. We welcome you to visit our facilities in person and explore tailor-made crane solutions designed to meet your specific requirements.