Heavy Duty Mg Type Double Beam Gantry Crane

Key Characteristics

Double Girder Design: Features two main box girders for superior strength, rigidity, and hook height compared to single girder designs.

Top-Running: The hoist trolley runs on rails on the top of the main girders. This provides the highest possible hook lift.

Heavy-Duty Construction: Built with reinforced girders, powerful drives, and high-capacity components for demanding cycles and heavy loads.

Electric Power: All functions-hoisting, trolley travel, and gantry travel-are powered by electric motors, not manual operation.

Freestanding: Like all gantry cranes, it is supported by legs that run on a ground-level runway, requiring no overhead building support.

 

Comparison: MG (Heavy Duty) vs. MH (Light Duty)

Feature	MG Type (Heavy Duty)	MH Type (Light Duty)
Girder Design	Double Box Girder	Single Trussed Girder
Operation	Fully Electric	Manual (Hoist & Travel)
Capacity	High (20 - 500+ Tons)	Low (0.5 - 10 Tons)
Duty Cycle	Severe, Continuous	Light, Occasional
Control	Cab or Radio Remote	Manual Chain Pulling
Cost	High Capital Investment	Low Capital Investment
Application	Heavy Industry, Production	Workshops, Maintenance

 

Lifting Capacity 320 tons
Span (Width) 3 - 12 meters (adjustable)
Lifting Height 3 - 10 meters
Working Class A3-A5 (light to medium duty)
Hoisting Speed 0.5 - 8 m/min (variable)
Main Beam Type Single/double girder (box-type)
Power Supply 220V/380V 3-phase or manual
Control Mode Pendant control/wireless remote
Hoist Type Electric chain hoist/wire rope hoist
Travel Drive Manual push or motorized
Corrosion Protection Hot-dip galvanized or marine-grade paint
Wind Resistance Up to Beaufort scale 6 (for outdoor use)
Operating Temp -20°C to +50°C

1. Structural System

This is the crane's skeleton, designed to withstand immense stress and prevent deflection.

Main Girders (2): The primary horizontal beams that form the bridge. They are fabricated from heavy steel plate into box girders for maximum strength and rigidity. This double girder design is what allows for high capacities and long spans.

End Cap Beams / Cross Beams: Horizontal members that connect the two main girders at each end, ensuring they remain parallel and adding torsional stability to the entire bridge.

Legs (2 or 4): The vertical support structures. In a typical MG crane, there is one leg at each end of the bridge, often configured as:

Rigid Leg: A fixed connection to the bridge for stability.

Driven / Flexible Leg: Houses the gantry travel drive machinery and may have a slight flexibility to accommodate track irregularities.

Diagonal & Horizontal Braces: Steel bracing between the legs and the girders. These are critical for absorbing lateral forces (like wind load or side-pull) and preventing the entire structure from swaying.

 

 

2. Hoisting System

The system responsible for the primary function: lifting and lowering the load.

Hoist Trolley: The unit that travels along the top of the main girders. It is itself a robust frame with wheels, driven by its own motor.

Main Hoist Unit: Mounted on the trolley, this is a powerful winch system consisting of:

Hoist Motor: A high-torque, heavy-duty electric motor.

Hoist Reducer (Gearbox): A multi-stage, precision gearbox that converts the motor's high speed into the powerful, low-speed torque needed for lifting.

Drum: A large steel cylinder around which the wire rope is spooled. Designed to prevent rope damage and ensure smooth spooling.

Wire Rope: High-strength, non-rotating steel rope capable of handling the rated load with a significant safety factor.

Brakes: A primary fail-safe brake (usually a disc or caliper type) that automatically engages when power is cut, and often an auxiliary brake for redundancy.

 

Hook Block: The assembly suspended from the wire rope, consisting of sheaves (pulleys) and the master hook. A block-and-tackle configuration provides mechanical advantage.

Auxiliary Hoist (Optional): A smaller, secondary hoist mounted on the same trolley for lighter loads, offering greater speed and precision.

 

 

3. Travel and Motion System

This system enables movement along the runway (gantry travel) and across the span (trolley travel).

Gantry Travel System (Crane Movement):

End Trucks: The assemblies at the bottom of each leg that contain the wheels, axles, and bearings.

Travel Wheels: Multiple large, forged or cast steel wheels per end truck to distribute the enormous weight.

Gantry Drive Motors: Powerful electric motors (usually one per driven leg) that provide the power to move the entire crane.

Gantry Reducers (Gearboxes): Reduce the motor speed to the required wheel speed.

Gantry Brakes: Spring-set brakes to stop and hold the crane position.

Trolley Travel System (Cross-Travel):

Trolley Drive Motor: Mounted on the trolley frame to power its movement across the bridge girders.

Trolley Reducer: A gearbox connected to the trolley wheels.

Trolley Wheels: Steel wheels that run on rails mounted on the top of the main girders.

 

 

4. Electrical and Control System

The nerve center that powers and commands all crane functions.

Power Supply:

Conductor Bar (Festoon) System: The most common method for MG cranes. An enclosed electrified rail system runs along the runway, with collectors on the crane drawing power. This is highly reliable for outdoor, heavy-duty use.

Cable Reel: A motorized drum that pays out and retracts a heavy power cable as the crane moves.

Control Panel / Cabinet: The "brain" of the crane, containing:

Variable Frequency Drives (VFDs): For smooth, controlled acceleration and deceleration of all motions (hoist, trolley, gantry), preventing load swing and reducing mechanical stress.

Programmable Logic Controller (PLC): Manages control logic, safety interlocks, and diagnostics.

Contactors and Overload Relays: To switch motors and provide protection.

Operator Interface:

Radio Remote Control (Most Common): Allows the operator to move freely on the ground for the best visibility and safety.

Operator's Cab: A mounted, enclosed cab with full control consoles and views down the span.

5. Safety and Ancillary System

Critical components that protect personnel, the load, and the crane itself.

Load Moment Indicator (LMI): A system that monitors the load on the hook and will alarm and cut out functions if the crane is overloaded or placed in a dangerous configuration.

Limit Switches: Automatically cut power to prevent the hoist block, trolley, or gantry from traveling beyond their designed limits.

Anemometer: A wind speed sensor that provides warnings and will automatically shut down crane operations if wind speeds exceed safe limits (critical for outdoor cranes).

Anti-Collision System: Uses sensors or radar to detect obstacles or other cranes and prevent collisions.

Buffers and End Stops: Energy-absorbing devices mounted on the end trucks and at the ends of the runway to absorb impact energy.

Lighting and Warning Devices: Mast lights, strobes, and audible alarms to warn personnel of crane movement.

SKETCH

 

Main technical

 

Advantages of Heavy Duty MG Type Double Beam Gantry Crane

The advantages stem from its fundamental design principles: a double box girder structure, electric power, and freestanding capability.

1. Exceptional Lifting Capacity and Strength

Core Advantage: The dual main box girders provide immense structural integrity and rigidity, minimizing deflection under load. This allows MG cranes to handle extremely heavy loads, typically from 20 tons up to 500 tons or more.

Robust Construction: Every component, from the forged wheels to the powerful drives, is built for continuous, severe-duty use in harsh environments like steel mills and foundries.

2. Maximum Hook Height

Top-Running Trolley: The hoist trolley runs on rails on top of the bridge girders, not underneath them.

Benefit: This configuration provides the greatest possible hook lift height under the crane, maximizing the usable vertical space in a facility. This is critical for handling tall loads or stacking materials.

3. Superior Stability and Precision

Rigid Structure: The double girder design is highly resistant to twisting and side-sway, ensuring stable and precise load control, even when handling long or awkward loads.

Advanced Control: Modern MG cranes are equipped with Variable Frequency Drives (VFDs) on all motions. This allows for smooth, controlled acceleration and deceleration, enabling operators to position multi-ton loads with pinpoint accuracy.

4. Freestanding Design and Outdoor Capability

No Building Support Required: The crane is supported by its own legs on a ground-level runway. It places zero stress on the building's structure.

Ideal for Any Location: This makes it perfect for outdoor applications (e.g., storage yards, shipping terminals) or inside buildings where the roof structure cannot support a crane.

5. Long Span and Full Coverage

The rigid double beam construction allows the crane to safely span very wide areas (35 meters / 115 feet and more), providing complete and unobstructed coverage of a large work area without needing intermediate supports.

6. Durability and Low Lifetime Cost

Built to Last: Designed for a long service life under abusive conditions, reducing long-term replacement costs.

Ease of Maintenance: Major components (drives, motors, electrical panels) are easily accessible on the platform for inspection and servicing, minimizing downtime.

7. Versatility and Customization

The crane can be outfitted with a wide range of below-the-hook devices beyond a standard hook, including:

C-hooks for lifting coils

Lifting beams for spreader bars

Magnets for steel scrap

Grapples for bulk material

Vacuum lifters for sheets

 

Applications of Heavy Duty MG Type Double Beam Gantry Crane

This crane is the workhorse of heavy industry, found wherever massive, high-value loads need to be moved safely and efficiently.

1. Steel Mills and Metal Processing

Use Case: Handling raw materials (coils, slabs, plates), moving ladles, charging scrap into furnaces, and handling finished products. This is the quintessential application for its durability and power.

2. Heavy Machinery and Equipment Manufacturing

Use Case: Moving large machine parts, fabrications, and assembled equipment (e.g., turbines, mining equipment, presses) during the manufacturing process.

3. Power Generation

Use Case: Installation and maintenance of massive components like turbines, generators, rotors, and transformers in power plants and hydroelectric facilities.

4. Shipbuilding and Dry Docks

Use Case: Assembling large ship sections, lifting and installing engines, and handling propellers. Its ability to span the width of a ship under construction is crucial.

5. Large-Scale Precast Concrete Production

Use Case: Handling massive and heavy precast concrete elements like bridge beams, wall panels, and structural components.

6. Ports and Intermodal Terminals

Use Case: Moving heavy project cargo, machinery, and containers within a terminal area, especially for breakbulk and heavy-lift cargo.

7. Aerospace Industry

Use Case: Precise handling and positioning of large, high-value aircraft components like wings and fuselage sections during assembly.

8. Railway Maintenance Facilities

Use Case: Lifting entire locomotives and railcars for repair and maintenance.

 

The production process of a 200-ton mobile boat/marine lift crane involves several stages, from design and engineering to fabrication, assembly, and testing. Below is a detailed breakdown of the typical production process:

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1. Design & Engineering

Conceptual Design: Engineers create initial sketches and 3D models based on load capacity (200 tons), reach, mobility, and environmental conditions (marine use).

Structural Analysis: Finite Element Analysis (FEA) ensures the crane can handle dynamic loads, wind, and wave forces.

Hydraulic & Electrical Systems: Design of hydraulic cylinders, winches, and control systems for smooth lifting operations.

Material Selection: High-strength steel (e.g., ASTM A514) for corrosion resistance in marine environments.

Regulatory Compliance: Meets standards like DNV-GL, ABS, or Lloyd's Register for marine cranes.

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2. Material Procurement

Steel Plates & Beams: Sourced for the boom, chassis, and structural framework.

Hydraulic Components: Pumps, cylinders, hoses, and valves from certified suppliers.

Electrical Systems: Motors, sensors, and control panels (often waterproof for marine use).

Wire Ropes & Sheaves: High-grade steel cables for lifting.

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3. Fabrication

A. Structural Fabrication

Cutting & Shaping: CNC plasma/laser cutting for precision parts.

Welding: Automated and manual welding (Submerged Arc Welding for thick sections).

Boom Construction: Lattice or telescopic design for strength and mobility.

Chassis & Outriggers: Reinforced for stability during lifts.

B. Hydraulic & Mechanical Assembly

Hydraulic System: Installation of pumps, cylinders, and hoses.

Winches & Drums: Mounted for lifting and lowering operations.

Slewing Mechanism: Allows 360° rotation (if applicable).

C. Electrical & Control Systems

Control Cabin: Waterproof operator station with joysticks/sensors.

Load Monitoring: Load cells and limit switches for safety.

Power Supply: Diesel engine or electric motor (marine-grade).

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4. Assembly & Integration

Boom Installation: Mounted onto the chassis with pivot points.

Counterweights: Added for balance (if required).

Final Wiring & Plumbing: Connecting hydraulic and electrical systems.

Painting & Coating: Anti-corrosion paint (epoxy or zinc coatings).

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5. Testing & Quality Control

Load Testing: Lifting 200 tons (+25% overload test, per standards).

Functional Tests: Checking hydraulic movements, rotation, and stability.

Environmental Tests: Salt spray tests for marine durability.

Safety Checks: Emergency stop systems, overload alarms.

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6. Delivery & Commissioning

Transport: Disassembled for shipping or delivered as a mobile unit.

On-Site Assembly: Reassembled at the dock or shipyard.

Operator Training: Handling and safety protocols.

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%.