21t Double Girder Beam Gantry Crane

 

A 21-ton double girder beam gantry crane is a robust, heavy-duty lifting system designed for handling large and heavy loads in outdoor and semi-outdoor environments such as construction sites, manufacturing yards, and logistics hubs. Unlike single girder gantry cranes, the double girder design offers increased strength, lifting height, and stability, making it ideal for operations where precision and high capacity are critical.

Key Features:

Lifting Capacity: 21 tons

Structure: Two main girders (double girder) supported by vertical legs and mounted on ground tracks or rubber tires

Lifting Mechanism: Trolley with electric wire rope hoist or open winch system running on top of the girders

Span: Customizable to site requirements, typically ranging from 10 to 35+ meters

Height: Can be designed for high lifting heights suitable for tall or bulky items

Mobility: Fixed (rail-mounted) or mobile (tyre-mounted) configurations

Control Options: Remote control, pendant control, or cabin operation

Applications:

Heavy equipment manufacturing

Precast concrete component handling

Steel structure assembly yards

Shipbuilding and marine industries

Container and cargo loading in logistics hubs

Advantages:

Greater lifting height and span than single girder models

High stability under heavy and wide loads

Efficient load distribution minimizes girder deflection

Suitable for demanding outdoor environments

 

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.Double Main Girders

Type: Welded box-type or I-beam steel girders.

Function: Support the trolley and distribute the load evenly across the span.

Advantages: Increased strength and reduced deflection under heavy loads.

 

Trolley with Lifting Mechanism

Mounted On: Top of the double girders.

Type: Electric wire rope hoist or open winch type hoist.

Function: Moves laterally along the girders and raises/lowers the load.

Includes: Motor, gearbox, brake, and drum system.

 

 

3.End Carriages / Gantry Legs

Structure: Two vertical support legs on each side, connecting the girders to the ground-level running gear.

Configuration: A-frame or box-type steel structure for stability.

Features: Some designs include flexible joints to accommodate uneven ground.

4.Crane Travel Mechanism

Type: Rail-mounted or rubber-tyred wheel assemblies.

Components:

Motors and reducers for longitudinal travel

Wheels (for ground movement)

Control: Synchronized drive system ensures stable movement.

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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

 

 

 

Advantages of a 21-Ton Double Girder Beam Gantry Crane

1. High Load Capacity with Enhanced Stability

The double girder structure provides excellent load-bearing strength and stability, making it suitable for handling heavy loads up to 21 tons consistently and safely.

2. Greater Lifting Height and Span

With the hoist or trolley running on top of the girders, the crane offers increased lifting height compared to single girder cranes, allowing it to handle taller loads and larger working areas.

3. Uniform Load Distribution

Double girders distribute loads more evenly across the span, reducing structural stress and extending the service life of the crane and support structures.

4. Precision Handling

Equipped with a trolley that moves along the girder and synchronized ground travel mechanisms, the crane offers precise positioning and movement, essential in manufacturing and assembly operations.

5. Versatile Applications

Ideal for both indoor and outdoor use in industries such as:

Precast concrete

Steel fabrication

Equipment manufacturing

Shipbuilding

Rail/bridge construction

6. Customizable Design

Can be tailored in terms of span, lifting height, travel speed, and power supply, making it adaptable to various site conditions and operational needs.

7. Improved Operational Efficiency

Reduces manpower and handling time for heavy materials, increasing throughput in production or construction environments.

8. Advanced Safety Features

Often equipped with:

Overload protection

Limit switches

Emergency stop buttons

Anti-wind and anti-collision devices
This ensures safe operation, especially in outdoor or high-traffic areas.

9. Remote or Cabin Control Options

Enhances operator safety and comfort by allowing remote control operation or use of an elevated cabin, improving visibility and reducing fatigue.

10. Lower Installation Costs vs Overhead Cranes

Especially when used outdoors, gantry cranes don't require building-mounted runways, saving on civil construction and installation expenses.

 

 

Applications of a 21-Ton Double Girder Beam Gantry Crane

A 21-ton double girder beam gantry crane is widely used in industrial and infrastructure sectors where heavy loads, large spans, and precise material handling are required. Its robust construction and adaptable design make it suitable for a variety of demanding environments.

1. Precast Concrete Yards

Use: Lifting and transporting large precast elements such as U-beams, box girders, and slabs.

Advantage: Handles long and heavy components safely and efficiently across open yards.

2. Bridge and Highway Construction

Use: Handling and placing large structural segments like girders and deck panels.

Advantage: On-site mobility and heavy lifting make it ideal for assembling long-span infrastructure.

3. Steel Structure Fabrication Plants

Use: Moving steel frames, beams, and plates for assembly and welding.

Advantage: Offers high lifting height and stable handling for bulky steel components.

4. Shipbuilding and Marine Industry

Use: Lifting ship parts, engines, and steel plates in open docks or yards.

Advantage: High capacity and weather-resistant design suits harsh outdoor conditions.

5. Heavy Equipment Manufacturing

Use: Transporting machine frames, dies, and components during assembly.

Advantage: Allows precise movement and heavy lifting in industrial environments.

6. Rail Yard & Metro Construction

Use: Placing U-girders or rail components during elevated rail or viaduct construction.

Advantage: Long span and custom lifting tools (e.g., beam clamps) support project-specific needs.

7. Logistics and Storage Yards

Use: Moving large containers, crates, or oversized cargo.

Advantage: Reduces reliance on forklifts or mobile cranes, improving logistics flow.

8. Power and Energy Sector

Use: Handling large transformers, turbines, and substation components.

Advantage: High lifting precision and capacity for sensitive, valuable equipment.

 

 

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%.