Electric Hoist Double Girder Overhead Crane

Advantages of Double Girder + Electric Hoist:

Higher Capacity

Handles heavier loads than single-girder cranes (up to 550+ tons).

Better Hook Height

The hoist is placed between the girders, maximizing vertical lift space.

Durability

Ideal for harsh environments (e.g., foundries, steel mills) with optional heat-resistant coatings.

Precision & Safety

Electric hoists offer finer control, overload protection, and fail-safe brakes.

Customizability

Can integrate magnet, grabber, or other attachments for specialized tasks.

 

Selection Considerations:

Load Capacity – Match the crane to your maximum load (+20% safety margin).

Span & Lift Height – Ensure the crane covers the required work area.

Duty Cycle – Choose between standard (CMAA Class B–D) or heavy-duty (Class E–F).

Power Supply – Typically 3-phase AC (380V, 480V, etc.).

Environment – Explosion-proof, high-temperature, or outdoor options available.

 

Comparison with Other Crane Types

Feature	Double Girder + Electric Hoist	Single Girder Crane	Gantry Crane
Max Capacity	5–550+ tons	1–20 tons	1–500 tons
Hook Height	Highest (hoist between girders)	Lower (hoist below girder)	Varies (depends on design)
Span	Up to 35m+	Up to 25m	Adjustable (outdoor use)
Precision	High (VFD control)	Moderate	Moderate
Cost	Higher initial cost	More economical	Mid to high range
Best For	Heavy industry, steel, power plants	Light workshops, warehouses	Outdoor yards, construction

 

A double girder overhead crane with an electric hoist consists of several key components that work together to enable safe and efficient lifting and movement of heavy loads. Below is a detailed breakdown of the main components:

 

1. Bridge (Double Girder Structure)

Main Girders (2) – The primary horizontal beams that span the width of the crane runway.

Made of welded steel (box-type or truss design).

Supports the trolley, hoist, and load.

End Trucks (2) – Wheeled assemblies at each end of the bridge that allow the crane to move along the runway rails.

Include drive motors, wheels, and brakes for longitudinal travel.

 

2. Electric Hoist & Trolley System

Electric Hoist – The lifting mechanism (either wire rope hoist or chain hoist).

Includes:

Motor (for lifting/lowering).

Drum or sprocket (for rope/chain winding).

Hook block (for attaching loads).

Brake system (electromagnetic or mechanical).

Limit switches (to prevent over-hoisting/lowering).

Trolley – The assembly that carries the hoist along the bridge girders.

 

Includes:

Trolley frame (supports the hoist).

Trolley wheels & drive motor (for cross-travel movement).

Buffers (to absorb shocks).

3. Runway System

Runway Beams – Support the crane's movement along the building length.

Can be top-running (rails on top of beams) or underhung (suspended from ceiling).

Runway Rails – Steel tracks that guide the crane's wheels.

Rail Clamps – Optional safety devices to prevent crane movement during maintenance.

4. Electrical System

Power Supply – Typically 3-phase AC (380V, 480V, etc.) via festoon system, cable reels, or conductor bars.

Control System –

Pendant control (handheld wired remote).

Radio remote control (wireless operation).

Cabin control (for large cranes, with operator seat).

Variable Frequency Drives (VFDs) – For smooth acceleration/deceleration.

Safety Devices –

Overload limiter.

Emergency stop.

Anti-collision sensors (for multiple cranes).

5. Safety & Auxiliary Components

Bumpers / Buffers – Absorb impact at crane travel limits.

Anemometer (for outdoor cranes) – Measures wind speed to prevent unsafe operation.

Lights & Alarms – Visual/audible warnings during operation.

Load Indicator – Displays real-time load weight.

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6. Optional Attachments

Magnet Lifter – For handling steel plates/scrap.

C-Hook / Grabber – For specialized loads (coils, barrels, etc.).

Anti-Sway System – Reduces load swing for precision positioning.

Summary of Key Differences vs. Single Girder Cranes

Feature	Double Girder Crane	Single Girder Crane
Girders	Two main beams	One main beam
Capacity	5–550+ tons	1–20 tons
Hook Height	Higher (hoist between girders)	Lower (hoist below girder)
Durability	More robust for heavy-duty use	Lighter, cost-effective
Cost	Higher initial cost	More economical

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SKETCH

Main technical

 

Double girder overhead cranes with electric hoists are widely used in heavy industries due to their superior strength, precision, and durability. Here are the key advantages:

1. Higher Lifting Capacity

Can handle 5 to 550+ tons, making them ideal for heavy-duty applications like steel mills and shipbuilding.

More stable than single-girder cranes when lifting near capacity.

2. Greater Hook Height

The hoist is mounted between the girders, maximizing vertical lifting space compared to single-girder cranes (where the hoist hangs below the girder).

3. Longer Span & Better Stability

Double girders provide higher rigidity, reducing deflection under heavy loads.

Suitable for wide spans (up to 35m or more) in large workshops.

4. Enhanced Durability & Long Service Life

Built with heavy-duty steel construction, resistant to deformation.

Better suited for harsh environments (high heat, dust, corrosive conditions).

5. Smoother & More Precise Control

Electric hoists offer variable speed control (via VFD) for precise load positioning.

Less load sway compared to chain hoists or manual cranes.

6. Safety Features

Overload protection (automatic cut-off if exceeding capacity).

Limit switches (prevents over-hoisting or over-travel).

Fail-safe brakes (holds load even during power failure).

7. Customizable Attachments

Can integrate electromagnets, grabs, C-hooks, or vacuum lifters for specialized material handling.

8. Lower Long-Term Maintenance

Electric hoists require less maintenance than hydraulic or pneumatic systems.

Fewer wear parts compared to chain hoists.

 

Applications of Electric Hoist Double Girder Overhead Cranes

These cranes are used in industries requiring heavy lifting, precision handling, and high-duty cycles.

1. Steel & Metal Industry

Handling steel coils, slabs, ingots, and castings.

Used in rolling mills, foundries, and forging plants.

2. Power Plants

Lifting turbines, generators, and heavy machinery during maintenance.

Handling boiler components and transformers.

3. Shipbuilding & Ports

Assembling ship hulls, engines, and large metal structures.

Loading/unloading heavy cargo in docks.

4. Automotive & Heavy Machinery

Moving press machines, stamping dies, and large vehicle parts.

Used in automobile assembly lines.

5. Mining & Cement Industry

Handling large crushers, kilns, and bulk materials.

6. Aerospace & Defense

Precision lifting of aircraft components, missiles, and defense machinery.

7. Warehousing & Logistics

Moving heavy containers, machinery, and large fabricated parts.

 

1.Design and Engineering
Requirements Gathering:

Load capacity (e.g., 10T, 50T, 100T, etc.), span, lifting height, and operational environment are defined.

Customization needs are assessed, such as control modes (pendant, wireless, cabin) and special features (e.g., anti-collision, overload protection).

Preliminary Design:

Structural engineers and crane designers create the crane's initial design, including the main beam, end carriage, lifting system, trolley system, travel mechanism, and other components.

Calculation and Simulation:

Load calculations are performed to ensure the crane can handle the specified capacity.

Finite element analysis (FEA) may be used to simulate stresses and deflections in the structure to ensure safety and stability.

Detailed Design:

After approval, detailed drawings for each part are made, including the main girder, end carriage, hoist system, motors, control systems, and safety features.

2. Material Procurement
Raw Material Selection:

High-quality materials like steel, alloyed steel, forged steel, and electrical components are sourced according to specifications.

Materials are inspected for quality certification and compliance with industry standards (e.g., ISO, CE).

Component Sourcing:

Standard components such as motors, hoists, control panels, limit switches, and safety devices are sourced from reliable suppliers.

3. Fabrication of Components
Main Girder:

Cutting and welding of steel plates to form the bridge girder.

The girder is assembled by welding or bolting sections, ensuring it meets the required strength and precision.

End Carriage Assembly:

The end carriage is fabricated and assembled to hold the crane on the runway rails.

Wheel assemblies are installed to ensure smooth travel along the rails.

Hoist and Trolley System:

The hoist unit (electric or manual) is assembled, including the drum, wire rope, hook, and motor.

The trolley system is built to transport the hoist across the bridge, including trolley wheels and drive mechanisms.

Crane Traveling Mechanism:

The crane wheels are mounted on the end carriages, ensuring smooth horizontal movement.

The drive system is installed to control travel speed.

4. Assembly of Crane
Main Beam Installation:

The assembled main girder is lifted and positioned onto the end carriages.

The girder is aligned to ensure structural integrity.

Trolley and Hoist Installation:

The trolley system is mounted onto the main girder, and the hoist is mounted to the trolley.

The load chain or wire rope is installed and tested for smooth operation.

Travel Mechanism Setup:

The crane wheels are fitted, and the drive mechanism is connected to the control system for horizontal movement.

5. Electrical and Control System Installation
Wiring and Control Panel:

The control panel is installed and wired to manage all crane movements (hoisting, trolley, crane travel).

Limit switches, emergency stop buttons, and safety alarms are integrated into the control system.

Motor and Gear Installation:

Motors for hoisting, traveling, and the trolley are installed and connected to their respective gear systems.

Testing of Control Systems:

Control systems are checked to ensure proper integration of pendant control, wireless remote, or cabin control options.

6. Testing and Quality Control
Load Testing:

The crane undergoes static load testing (to check stability) and dynamic load testing (to check operational performance under actual working conditions).

Overload protection and limit switches are tested to ensure they function correctly.

Safety System Testing:

The sound and light alarms, limit switches, emergency stop buttons, and safety devices are all tested for functionality.

Movement Testing:

All movements-hoisting, trolley movement, bridge travel, and sway control-are tested for smooth operation and precision.

Electrical Testing:

All electrical components are tested for proper wiring, grounding, and communication between systems.

Documentation and Certification:

The crane is inspected according to international safety standards and undergoes certification by relevant authorities (e.g., CE, ISO).

Test certificates for motors, cranes, and load testing are prepared.

7. Final Inspection and Painting
Visual Inspection:

A thorough inspection is carried out to ensure that the crane meets design specifications and safety requirements.

Painting:

The crane is painted with high-quality anti-corrosion coatings to protect it from environmental conditions.

Marking and Labeling:

Safety labels, warnings, and capacity markings are applied to the crane for proper identification.

8. Delivery and Installation
Shipping:

The crane is carefully disassembled into transportable parts (if needed) and shipped to the customer's location.

Installation:

The crane is installed on-site, and all connections (power, mechanical, control) are made.

Final Commissioning:

The crane is commissioned by running it through a series of operational tests to ensure it works properly.

Operator training is conducted, if necessary, for safe and efficient use.

9. Post-Installation Support
Customer Training:

Operator training on how to use the crane safely and effectively.

Maintenance Schedule:

Providing a maintenance plan for the crane's continued operation, including regular inspections, lubrication, and testing.

After-Sales Support:

Offering spare parts, troubleshooting, and repair services.

Workshop view:

The company has installed an intelligent equipment management platform, and has installed 310 sets (sets) of handling and welding robots. After the completion of the plan, there will be more than 500 sets (sets), and the equipment networking rate will reach 95%. 32 welding lines have been put into use, 50 are planned to be installed, and the automation rate of the entire product line has reached 85%.