30t MG Double Girder Rail Mounted Gantry Crane

Key Characteristics

Rail-Mounted: Unlike rubber-tired gantries (RTGs), RMGs run on fixed steel rails embedded in a concrete foundation. This provides exceptional stability and allows for very precise positioning.

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

Electric Power: All functions are powered by electricity, typically drawn from an external power source via a flexible cable or conductor system.

High Capacity and Span: Designed for very heavy loads (20 to 500+ tons) and can span wide areas, often covering multiple container or cargo rows.

 

Comparison: RMG vs. RTG

Feature	MG Double Girder RMG	Rubber-Tired Gantry (RTG)
Mobility	Fixed rails, limited to rail path	Highly mobile on rubber tires
Precision	High, due to fixed rails	Moderate, requires skilled operation
Infrastructure	Requires fixed rail installation	Only needs a paved surface
Cost	Higher initial infrastructure cost	Lower infrastructure cost, higher fuel/maintenance
Stacking Density	Very high, suitable for dense storage	High, but slightly less than RMG
Environment	Electric, low emissions	Typically diesel-powered, higher emissions

 

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

An MG (Gantry, Hook) RMG is a complex and robust system designed for heavy-duty, high-precision material handling in a fixed path, typically in port yards, intermodal terminals, and large industrial storage areas. Its components are built for extreme durability, precise control, and often, automation.

The components can be categorized into five main systems:

 

1. Structural System

This is the crane's skeleton, designed to handle immense loads with minimal deflection.

Main Girders (2): The primary horizontal beams that form the bridge. They are fabricated as welded box girders for maximum strength and rigidity. This double girder design is essential for spanning wide areas and supporting heavy loads.

Legs / Supports: Typically four vertical structures (two at each end) that connect the main girders to the end trucks. The leg height determines the stacking height underneath the crane.

Diagonal & Horizontal Braces: Steel bracing between the legs and the girders. These are critical for absorbing lateral forces (like wind load) and preventing the entire structure from swaying, ensuring stability during operation.

 

2. Hoisting and Trolley System

The system responsible for the actual lifting, lowering, and cross-travel of the load.

Hoist Trolley: A heavy-duty frame that runs on rails mounted on the top of the main girders.

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

Hoist Motor: A high-torque, electric motor.

Hoist Reducer (Gearbox): A precision gearbox that converts high motor speed into powerful, low-speed torque for lifting.

Drum: A large steel cylinder around which the wire rope is spooled.

Wire Rope: High-strength, non-rotating steel rope with a significant safety factor.

Brakes: Primary and secondary fail-safe brakes (usually disc type) that automatically engage to hold the load.

 

Spreader: The specialized below-the-hook device for container handling. It includes:

Twistlocks: Hydraulically-operated pins that engage the corner castings of a shipping container.

Telescopic Mechanism: Allows the spreader to adjust length for 20ft, 40ft, and 45ft containers.

Trolley Travel System:

Trolley Drive Motors: Power the movement of the trolley along the bridge girders.

Trolley Wheels: Steel wheels that run on rails atop the main girders.

Trolley Reducers: Gearboxes that provide controlled torque to the wheels.

 

 

3. Gantry Travel System (Crane Propulsion)

This system moves the entire crane along the fixed runway.

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

Travel Wheels: Multiple large, forged steel wheels per end truck to distribute the crane's enormous weight onto the rails.

Gantry Drive Motors: Powerful electric motors that provide the torque to move the massive crane structure.

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

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

 

 

4. Rail and Runway System

The fixed infrastructure that guides and supports the crane.

Runway Rails: Heavy-duty steel rails (e.g., QU100, QU120 standards) that are precisely aligned and grouted into a massive concrete foundation. This foundation is critical for handling the dynamic loads.

Rail Clips and Baseplates: Secure the rail to the concrete foundation beam.

5. Electrical and Control System

The nerve center that powers and commands all crane functions, often with a high degree of automation.

Power Supply:

Conductor Bar (Enclosed Track) System: The most common and reliable method. An electrified rail system runs parallel to the crane runway, and collectors on the crane draw power from it. This is ideal for long travel distances and automated operation.

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

Control Panel / Cabinet: Houses the intelligent control systems:

Variable Frequency Drives (VFDs): For smooth, controlled acceleration and deceleration of all motions (hoist, trolley, gantry), which is essential for precise positioning and preventing container swing.

Programmable Logic Controller (PLC): The "brain" of the crane. It manages all control logic, safety interlocks, and automated sequences.

Automation Systems: For RMGs, this often includes software for automated stacking (ASC - Automated Stacking Cranes), container management, and collision avoidance.

Operator Interface:

Radio Remote Control: Standard for manual operation, giving the operator mobility and the best view.

Operator's Cab: Can be mounted on the crane for full-time operation, though many modern RMGs are designed for remote control stations or full automation.

Sensors and Safety Devices:

Load Moment Indicator (LMI): Monitors the load weight to prevent overload.

Anti-Sway System: Uses algorithms and VFD control to minimize container swing.

Anti-Collision System: Uses laser or radar sensors to detect obstacles and other cranes, automatically stopping movement to prevent accidents.

Anemometer: Measures wind speed and can automatically slow or stop operations if limits are exceeded.

Limit Switches: Prevent the trolley and hoist from over-traveling.

Positioning Systems: GPS or laser-based systems to pinpoint the crane's exact location on the runway for automation.

SKETCH

 

Main technical

 

Advantages of MG Double Girder RMG Cranes

The advantages of RMGs stem from their fixed-rail design, double girder structure, and electrified operation, making them superior to mobile alternatives like RTGs in specific settings.

1. Exceptional Stability and Precision

Fixed Rail Guidance: Running on precisely aligned steel rails embedded in a concrete foundation eliminates drift and ensures perfectly straight travel. This allows for extremely accurate positioning, which is critical for automated operations and high-density stacking.

Rigid Double Girder Structure: Provides immense strength and minimizes deflection and sway, even when handling maximum loads at high speeds. This stability is essential for precise load placement.

2. High Efficiency and Productivity

Fast Cycling Speeds: The stable platform allows for higher trolley and gantry travel speeds without compromising safety or control, leading to more moves per hour (higher productivity).

Smooth Operation: Equipped with Variable Frequency Drives (VFDs) on all motions for controlled acceleration and deceleration, reducing load swing and enabling pinpoint accuracy.

3. Superior Stacking Density and Space Utilization

Wide Span Capability: RMGs can be designed with very long spans, allowing them to cover 8 or more container rows and stack containers 5-6 high.

Narrow Aisle Operation: The fixed path allows for stacking with very narrow aisles between crane rails, maximizing storage capacity on valuable land in ports and terminals.

4. Lower Operational Costs and Environmental Benefits

Electric Power: Connected to the grid via conductor bars or cable reels, they use clean electrical energy. This eliminates diesel fuel costs and dramatically reduces greenhouse gas emissions and noise pollution compared to diesel-powered Rubber-Tired Gantries (RTGs).

Reduced Maintenance: Without engines, transmissions, or rubber tires to maintain and replace, maintenance costs are significantly lower. The rail system also causes less wear and tear on the crane itself compared to uneven pavement.

5. Ideal for Automation and Integration

Predictable Path: The fixed rail makes it the perfect candidate for full automation. RMGs can be easily integrated into Terminal Operating Systems (TOS) to become Automated Stacking Cranes (ASCs), operating unmanned 24/7.

Advanced Safety Systems: Automation packages include anti-collision systems, container profiling (to detect misaligned containers), and auto-steering, which enhance safety and efficiency beyond manual capability.

6. High Lifting Capacity and Durability

Built for Severe Duty: The double girder box design is capable of handling very heavy loads, typically from 40 to 60 tons (and more) for standard container handling, built to withstand continuous, heavy-duty cycles.

 

Applications of MG Double Girder RMG Cranes

The application of RMGs is highly specialized, focused on environments that benefit from their stability, density, and potential for automation.

1. Container Terminals and Ports (Primary Application)

Use Case: The quintessential application. RMGs are the backbone of modern container yards, used for:

Stacking containers transferred from ship-to-shore cranes.

Loading and unloading trucks and railcars in intermodal yards.

Inter-stack transfer and storage organization.

2. Intermodal Rail Terminals

Use Case: Moving containers directly from railcars to storage stacks and onto trucks. The precision of an RMG is ideal for working with rail infrastructure.

3. Logistics Parks and Freight Stations

Use Case: Large-scale distribution centers and container freight stations (CFS) that require high-density, organized storage for containers and heavy cargo.

4. Heavy Industry and Manufacturing

Use Case: While less common than in ports, large manufacturing plants (e.g., for heavy machinery, wind turbines) use RMGs for handling large, heavy components in a structured storage yard.

 

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:

---

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.

---

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.

---

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).

---

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).

---

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.

---

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%.