Electric Double Main Girder Trolley Gantry Crane

1. Overview

An Electric Double Main Girder Trolley Gantry Crane is a type of gantry crane widely used for heavy lifting in industries such as ports, shipyards, construction sites, and large-scale manufacturing facilities. The crane is designed to lift, move, and precisely position heavy loads over large areas.

"Double Main Girder" means the crane has two primary girders that span the width of the crane runway. This design provides higher load capacity and structural stability.

"Trolley" refers to the hoisting mechanism that moves horizontally along the girders.

"Electric" means that all operations-lifting, trolley movement, and crane movement-are powered electrically.

2. Main Components

Main Girders: The two primary beams that carry the trolley and distribute the load to the legs.

End Trucks / Legs: Vertical supports on either end, running along the runway rails.

Trolley: Moves along the main girders and carries the hoisting equipment.

Hoist: The lifting mechanism, typically electric, can be hook type or magnetic (for scrap handling).

Runway Rails: Tracks on the ground or elevated beams along which the crane travels.

Electrical System: Powers hoist, trolley, and crane travel; often includes controls for safety and precision.

Control System: Can be cabin-operated, remote-controlled, or semi-automatic.

3. Features and Advantages

High Load Capacity: Double girders allow heavy lifting, often hundreds of tons.

Large Span and Coverage: Can cover a wide work area.

Precision Handling: Electric trolley allows smooth and accurate load positioning.

Durability: Heavy-duty steel structure ensures long-term use.

Safety Features: Overload protection, emergency stop, anti-collision devices, and limit switches.

4. Applications

Shipping yards and container handling

Steel plants and manufacturing facilities

Heavy equipment assembly

Construction of bridges or large structures

Warehouses requiring high lifting capacity

5. Working Principle

Hoisting: The hoist lifts the load vertically.

Trolley Movement: The trolley moves the load along the girder to the desired position.

Crane Travel: The entire crane moves along the runway rails to cover different work areas.

Load Positioning: Operators control the load accurately using electrical or remote controls.

In short, an Electric Double Main Girder Trolley Gantry Crane is a robust, efficient, and versatile lifting solution for industrial environments that require heavy-duty lifting over large areas. Its design focuses on strength, precision, and safety.

Core Components：Engine, Bearing, Gearbox, Motor, Gear

Place of Origin：Henan, China

Warranty：2 years

Weight (KG)：50000 kg

Video outgoing-inspection：Provided

Machinery Test Report：Provided

Application：Outdoor

Keywords：Gantry Crane

Rated Loading Capacity：50Ton

Cross travelling speed：44.6m/min

Long travelling speed：47.1m/min

Control way：cabin

Power supply：Cable reel

Steel track：QU80

Power：3-phase AC 50HZ 380V

1.Main Girders (Primary Beams)

Two large steel beams running along the crane's width.

Carry the trolley and transfer the load to the end trucks.

Designed to handle heavy loads and minimize bending.

End Trucks / Legs

Vertical structures at both ends of the crane.

House the wheels that run along the runway rails.

Provide support and stability for the crane structure.

The main beam in a double girder gantry crane consists of two parallel girders connected by stiffeners or braces. These are typically box-shaped or truss-shaped, depending on the design and load requirements.Box girder design: Made of welded steel plates, providing high torsional rigidity and strength.Truss girder design: Lightweight but less commonly used due to lower load capacities.

The main beam of a Double Main Girder Gantry Crane is a critical structural component designed to provide support and stability for the crane's operations.High-strength steel (e.g., Q345B or Q235B) is commonly used for the main beam to ensure durability and the ability to handle heavy loads.The main beam supports the hoist or trolley carrying the load across the span of the crane.The length of the main beam is determined by the width of the area to be covered, which can vary significantly based on application.Rigidity: Properly engineered to resist bending, twisting, and vibrations during operation.

Functions

Support for Lifting Mechanism: It houses the trolley and hoist that carry out lifting tasks.

Stability: Ensures the stability of the crane by evenly distributing loads.

Efficiency: Designed to optimize load movement across the working area.

Design Considerations

Load Requirements: Calculated based on the maximum load and dynamic forces the crane will encounter.

Span and Height: Dictated by the size of the workspace and the required lifting height.

Safety Factors: Includes features like deflection limits, fatigue resistance, and compliance with industry standards (e.g., FEM, CMAA).

Lifting Components

Trolley

Moves along the length of the main girders.

Carries the hoist and allows horizontal positioning of the load.

Hoist

Lifting mechanism mounted on the trolley.

Types:

Electric wire rope hoist (for general heavy lifting)

Electromagnetic hoist (for handling scrap metal)

Includes motor, drum, wire rope or chain, hook, and braking system.

Hook / Load Attachment

The point where the load is connected.

May include special lifting devices like clamps or magnets depending on the application.

Motor: The motor of the lifting system in a double main girder gantry crane is a critical component designed to provide the necessary power and torque for lifting and lowering heavy loads safely and efficiently.

2) Reducer: The reducer of the lifting system in a double main girder gantry crane is a critical mechanical component that transfers power from the motor to the hoisting mechanism. It reduces the motor's high-speed rotation into lower speeds suitable for the crane's lifting and lowering operations while maintaining torque.

3) Drum: The drum of the lifting system in a double main girder gantry crane is a critical component that facilitates the lifting and lowering of loads.

4) Wire rope: Wire ropes are generally made of steel wires twisted together to form strands, which are then laid around a core.The core can be made from steel wire (indicating higher strength) or fiber (offering more flexibility).

5) Pulley block: TA pulley block in a lifting system of a double main girder gantry crane plays a crucial role in the crane's operation by facilitating the movement of the lifting cable or rope.

6) Lifting device: The lifting device in a Double Main Girder Gantry Crane is an essential part of the crane's lifting system, designed to handle heavy loads with precision and stability.

3.End carriage

1) The end carriage of a Double Main Girder Gantry Crane is a critical component of its structural and operational system. It connects the main girders to the wheels or tracks, providing stability and ensuring the crane's structural integrity.Equipped with wheels or bogies, the end carriage enables the crane to move along the tracks laid on the ground or across gantry beams.Distributes the weight of the crane and the load evenly across the wheels and tracks.

2) The end beam is typically made of high-strength steel to withstand heavy loads and environmental conditions.

3) The end beam is designed to support the specific load-bearing requirements of the crane.

4.Crane travelling mechanism

1) Working principle

The wheels are attached to axles or wheel blocks that help in distributing the load evenly across the crane.The drive motor activates the wheels through a system of gears and reducers, converting the motor's rotational force into torque.The wheels, mounted on the frame of the crane, roll along the rails on which the gantry structure is placed.The power to the wheels is transmitted via a combination of chains, belts, or direct coupling depending on the design of the crane.The crane traveling mechanism of a Double Main Girder Gantry Crane involves synchronized wheel and motor systems that enable the crane to move along its designated rails, with additional features ensuring safe, balanced, and efficient operation.

2) Functions of the crane operating mechanism

Horizontal movement: The primary function of the crane travelling mechanism is to move the entire crane structure along the rails or tracks that are placed on the ground or the sides of the installation area.

Support and Stability:The travelling mechanism ensures the crane is securely supported on the rails or tracks. It helps distribute the weight of the crane evenly and provides stability during movement.

Power Transmission:The crane travelling mechanism is powered by electric motors that drive wheels or gear systems. These motors convert electrical energy into mechanical energy, propelling the crane forward or backward.

Load Distribution:The travelling mechanism helps distribute the load evenly across the crane's wheels and tracks, preventing damage and ensuring the durability of the crane and its components.

5.Trolley travelling mechanism

1) Structural composition

Trolley frame: The frame is typically made of high-strength steel to support the load and withstand the stresses during operation.

Wheel set: The trolley is equipped with wheels that run on the rails of the main girder. These wheels are often made of hardened steel or cast steel to ensure durability and wear resistance.

Drive device: Electric motors are commonly used to provide the necessary power for the trolley's movement A gearbox is used to control the speed and torque of the trolley's movement.Couplings connect the motor to the gearbox and ensure smooth transmission of power to the wheels.

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2) Function of the trolley operating mechanism

Horizontal Movement: The primary function of the trolley traveling mechanism is to move the trolley horizontally across the length of the main girders. This movement allows the crane to position the hoist over a desired load location.

Load Handling: By moving along the main girders, the trolley helps in positioning the hoist system accurately above the load, which is necessary for lifting and transferring goods efficiently.

Power Transmission: The traveling mechanism typically uses electric motors and gear systems to provide the necessary torque and speed for the trolley's movement. The motors can be either AC or DC, depending on the design and requirements of the crane.

Rails and Wheels: The trolley runs on rails that are mounted on the main girders. The wheels on the trolley are designed to travel along these rails, ensuring smooth and stable movement. The wheels may be fitted with flanges to prevent lateral movement and maintain alignment.

Safety Mechanisms: The traveling mechanism is equipped with safety features such as limit switches, braking systems, and overload sensors to prevent accidents and ensure the safe operation of the crane.

6.Crane wheel

1) Function of wheels

Load Bearing: In a double main girder gantry crane, each wheel supports a significant portion of the crane's load. The wheels must be engineered to handle both the static and dynamic loads imposed during lifting operations.

Material Handling and Safety: The design of crane wheels must ensure safe operation, especially when handling heavy or oversized loads. The wheels should be engineered to minimize noise and vibrations during operation.

Rail Compatibility: Crane wheels are designed to run on specific rail types (e.g., flat or curved tracks). The size and shape of the wheel flange must match the rail profile to ensure proper fit and smooth operation.

2) Design requirements

Material and Design: Crane wheels are typically made of high-strength steel or cast iron to withstand the heavy loads and stresses associated with lifting and transporting materials. The design often includes a flange to ensure proper alignment and prevent the wheels from derailing off the tracks.

7.Crane Hook

The crane hook of a double main girder gantry crane is an essential component used for lifting and transporting heavy loads.

Design and Structure

Material: Typically made of high-strength steel to withstand heavy loads and provide durability.

Shape: The hook often has a C-shape or a pointed end for securely holding lifting slings or chains.

Size and Capacity: It is designed to match the lifting capacity of the crane, which can range from a few tons to several hundred tons for large industrial cranes.

Types of Hooks

Single Hook: Common in standard applications, used for lifting a load from a single point.

Double Hook: Utilized when a more balanced load is needed, often in double main girder designs for higher lifting capacities.

Crab Hook: In gantry cranes, the hook may be mounted on a trolley or crab that runs along the girders.

Motor

The motor of a double main girder gantry crane is an essential component that provides the power necessary for lifting, traveling, and sometimes rotating the crane's hoist or trolley system.The motor's power rating must match the crane's capacity and the load it needs to lift. Typically, these motors range from a few kilowatts up to hundreds of kilowatts, depending on the lifting and traveling requirements.

Motors can be equipped with variable frequency drives (VFDs) for smooth speed adjustments and energy savings.Safety and control systems like overload protection, braking systems, and emergency stops are incorporated for safe operation.

The motor should be compatible with the electrical supply available at the operating site, which can vary (e.g., 380V/50Hz, 480V/60Hz).The motor in a double main girder gantry crane is used for operations such as lifting heavy loads, moving the crane along the tracks (longitudinal travel), and sometimes lateral movement (cross travel) of the hoist or trolley.

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Sound and light alarm system & limit switch

1) Sound and light alarm system

A double main girder gantry crane, commonly used in heavy-duty operations, often incorporates safety mechanisms like sound and light alarm systems to ensure safe operations.

Sound Alarm (Horns/Buzzers): These are typically loud, audible devices that emit a distinctive sound to alert people in and around the working area. The sound level is designed to be high enough to be heard over operational noise.

Light Alarm (Flashing Lights/Beacons): Visual signals, such as flashing lights or rotating beacons, help alert personnel visually, especially in noisy environments where sound alarms may be insufficient.

2) Limit switch

A limit switch on a Double Main Girder Gantry Crane is a safety device used to prevent the crane from moving beyond a designated range. This ensures the protection of both the crane and its surroundings, as well as any loads being lifted.

Key Functions of Limit Switches:

Position Control: The limit switch helps monitor and control the position of the crane's trolley, hoist, and gantry to prevent over-travel and collisions.

Safety Shutdown: If the crane moves past its allowed limits, the limit switch signals the control system to stop the motor and prevent damage or hazardous situations.

Emergency Stop: It can act as an emergency cutoff to shut down the crane when it approaches the limits of its track or rail, preventing it from derailing or causing accidents.

Types of Limit Switches Used:

Mechanical Limit Switches: Activated by physical contact, often using a lever or cam that triggers the switch when moved by the crane's motion.

Electronic Limit Switches: Use sensors (e.g., inductive, capacitive, or optical sensors) for non-contact detection, providing higher durability and reducing wear and tear.

Rotary Limit Switches: Typically used in applications where rotational motion needs to be monitored, such as in hoists.

Linear Limit Switches: Used for applications where linear travel is monitored, commonly found in the movement of the trolley.

10.Safety Devices

1) 1. Overload Protection Device

Function: Prevents the crane from lifting loads that exceed its rated capacity.

2. Limit Switches

Function: Prevents the crane from moving beyond a set range during operations.

3. Emergency Stop Button

Function: Allows operators to quickly shut down the crane in case of an emergency.

4. Anti-Collision Device

Function: Prevents collisions between the crane and other structures or equipment.

5. Load Sway Control

Function: Reduces load sway during operations, which can be dangerous if uncontrolled.

6. Brake Systems

Function: Ensures that the crane remains in a stationary position when not in motion.

7. Safety Interlocks

Function: Prevents the operation of the crane if certain safety conditions are not met.

8. Warning Alarms and Signal Lights

Function: Alerts personnel in the vicinity of the crane's movement.

9. Anti-Tipping Device

Function: Protects against crane tipping due to uneven load distribution or excessive loading.

10. Cooling System for Motors

Function: Prevents motors from overheating during extended use.

11. Remote Control Systems

Function: Allows operators to control the crane from a safe distance.

12. Crane Monitoring Systems

Function: Provides real-time monitoring of operational parameters such as load weight, speed, and position.

13. Lighting and Visibility Aids

Function: Ensures that the operator has clear visibility, especially in low-light conditions.

11.Control Mode

1)1. Pendant Control

Description: The crane operator uses a wired control pendant to manage the movement of the crane and hoist.

Advantages: Simple to use, cost-effective, and provides direct control from a safe distance.

Usage: Commonly used in stationary or semi-stationary operations where the operator can be close to the crane.

2. Radio Remote Control

Description: Operators use a wireless control unit, which communicates with the crane via radio signals.

Advantages: Offers more flexibility as the operator can control the crane from a greater distance and access hard-to-reach areas.

Usage: Ideal for more complex operations and environments where operator mobility is essential.

3. Cabin Control

Description: The operator sits in a cabin on the crane itself and controls it using a combination of joysticks, buttons, or other controls.

Advantages: Provides a better view of the working area and greater precision in controlling the crane.

Usage: Suitable for heavy-duty operations or when a higher level of control is needed for positioning and maneuvering.

4. Automated Control (Semi-Automatic and Fully Automated)

Description: The crane can be controlled by programmed commands or integrated with automated systems for autonomous operation.

Advantages: Reduces human intervention, improves precision, and enhances safety for repetitive tasks.

Usage: Often used in large-scale operations where high efficiency and continuous operation are necessary.

5. Hybrid Control

Description: Combines manual operation (using pendant, remote, or cabin control) with automated features that can be engaged as needed.

Advantages: Offers versatility for operators who need to switch between manual and automated modes for specific tasks.

Usage: Common in systems designed to be adaptable to various operational requirements.

12.Sketch

Main technical

1. Increased Load Capacity

Enhanced Strength: The double main girder design provides additional structural strength and stability, allowing the crane to handle heavier loads compared to single girder models.

Better Load Distribution: The two main girders distribute the weight evenly, which enhances the crane's ability to lift large and heavy items.

2. Higher Lifting Height

Greater Clearance: The double girder setup allows for a higher lifting height, which is essential for industries needing to stack or lift tall loads.

Adaptability: The increased clearance can accommodate more complex lifting tasks, such as those involving large equipment or machinery.

3. Improved Stability and Safety

Reduced Sway: The design of the double main girder crane offers more stability, minimizing load sway and enhancing safety during operation.

Stronger Framework: The additional girder adds rigidity to the crane, which helps reduce the risk of structural deformation under heavy loads.

4. Versatility in Application

Adaptable to Various Industries: These cranes are suitable for use in shipyards, construction sites, large warehouses, and industrial facilities, where heavy lifting and long spans are common.

Customizable Design: Double girder gantry cranes can be customized with different specifications for various types of loads, heights, and spans.

5. Enhanced Performance

Higher Speeds and Precision: These cranes can be equipped with advanced control systems that allow for faster and more precise movements.

Reduced Maintenance: The robust construction can reduce wear and tear over time, leading to lower maintenance needs and increased operational lifespan.

6. Reduced Support Structure Costs

Longer Spans: The double girder design allows for longer spans without the need for frequent support columns, potentially reducing the overall cost of infrastructure.

Optimized Space Utilization: The crane's ability to cover a larger area efficiently can help maximize the use of available space in an industrial setting.

7. Safety Features

Advanced Safety Mechanisms: Double girder cranes can be equipped with additional safety features such as limit switches, emergency stop buttons, and anti-collision systems.

Improved Operator Safety: Their stable structure and ease of control contribute to a safer working environment for operators.

8. Flexibility with Lift Equipment

Compatibility: Double girder gantry cranes can be fitted with different types of lifting equipment such as hoists, winches, and spreader beams to adapt to various load handling requirements.

1. Port Operations

Container Handling: Double main girder gantry cranes are commonly used at ports for lifting and transferring containers between ships and storage yards. Their high capacity and reach allow them to handle heavy and large cargo efficiently.

Bulk Material Loading/Unloading: These cranes can also manage bulk goods such as coal, iron ore, or grains.

2. Shipyards

Ship Construction and Repair: They are used to move heavy sections of ships during assembly or repair. The cranes' ability to cover wide spans and support significant weight makes them suitable for handling steel components and other large ship parts.

Launching and Docking: Double main girder gantry cranes assist in moving ships in and out of dry docks or onto slipways.

3. Construction Sites

Building Materials: In large-scale construction projects, these cranes facilitate the transport of building materials such as steel beams, concrete panels, and other heavy components across vast construction zones.

Bridge and Infrastructure Projects: The high capacity and long reach make them ideal for lifting heavy prefabricated segments and assembling infrastructure like bridges.

4. Steel Industry

Steel Handling: They are used to lift and transport heavy steel plates, coils, and beams within steel plants for processing, storage, or shipment.

Overhead Lifting: Double main girder gantry cranes are also used for overhead handling within facilities where wide spans are necessary.

5. Heavy Machinery Manufacturing

Assembly Line Support: These cranes can move large machinery components across the assembly line during the manufacturing process.

1. Design and Engineering

Blueprint and Structural Design: Engineering teams design the crane based on specifications, considering the weight, span, lifting capacity, and working environment.

Component Specifications: Detailed specifications for components such as the main girders, end beams, hoist system, trolley, and electrical components are prepared.

2. Material Selection and Procurement

Steel Material Selection: High-strength steel materials are chosen for the main girders, columns, and other critical parts.

Procurement: Materials, such as steel plates, sections, bolts, and electrical components, are sourced and inspected for quality.

3. Cutting and Pre-Fabrication

Cutting and Shaping: Steel components are cut, shaped, and welded into preliminary forms according to the design specifications.

Pre-Fabrication Assembly: Components such as beams and girders are pre-assembled to verify that they fit together properly.

4. Welding and Structural Assembly

Welding: Main girders, columns, and other structural components are welded to create a sturdy framework. Specialized welding techniques are used to ensure strength and durability.

Structural Assembly: The main girders and end beams are assembled, ensuring precise alignment for balanced load distribution.

Quality Control: Welding seams and joints are inspected using non-destructive testing (e.g., ultrasonic or X-ray testing) for any structural defects.

5. Machining and Finishing

Machining of Parts: Critical parts such as the wheels, trolley components, and hoists undergo machining for proper fitting and smooth operation.

Surface Treatment: Steel parts are cleaned and subjected to surface treatments like sandblasting and coating to prevent rust and enhance durability.

Painting and Coating: Protective coatings are applied for weather resistance, with a primer followed by top coats.

6. Assembly of Crane Components

Main Girder Assembly: The two main girders are mounted and aligned.

End Beam Installation: End beams are fixed to the main girders, forming the frame of the crane.

Hoist and Trolley Installation: The hoist mechanism and trolley are mounted on the main girder rails and tested for alignment and operational smoothness.

7. Electrical and Control Systems Installation

Wiring and Cabling: Electrical wiring is installed for power supply, control circuits, and safety systems.

Control Panel and Safety Features: The control panel is mounted, with safety features such as limit switches, emergency stops, and overload protection integrated and tested.

Control System Programming: The crane's control system is programmed and tested for correct operation.

8. Testing and Quality Assurance

Load Testing: The crane is subjected to load tests to ensure it can handle its rated capacity without issues.

Operational Testing: Functional tests are performed to check movements, responsiveness, braking systems, and electrical operations.

Inspection and Certification: The crane undergoes final inspections to verify compliance with safety regulations and standards. Certification may be issued by relevant authorities.

9. Final Adjustments and Delivery Preparation

Final Adjustments: Any minor adjustments are made to ensure smooth operation.

Documentation: Operation manuals, maintenance guidelines, and certification documents are prepared for delivery.

Packaging and Shipping: The crane is packaged securely for shipment, ensuring all parts are protected during transit.

10. Installation and Commissioning (at Site)

On-site Assembly: The crane is assembled at the customer's location if required.

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%.