Heavy Duty QD Double Girder Overhead Crane

The QD model double girder overhead crane is a heavy-duty bridge crane engineered for efficient material handling in demanding industrial environments. It adopts a double-girder box-type structure with a winch trolley system, ensuring high lifting capacity, structural stability, and long service life.

It is widely used for loading, unloading, transporting, and positioning heavy materials in workshops, warehouses, steel plants, and open yard operations.

 

PRODUCT COMPARISON TABLE

Attribute	Heavy-Duty QD Double Girder Overhead Crane	QD Heavy Duty Double Girder Crane with Safe Hoist	QD Double Girder Crane with Electric Hoist	Custom QD Double Girder Overhead Crane
Capacity	Up to 400–500T	~100–200T	~50T	20–200T
Duty Class	A7–A8	A6–A7	A5–A6	Configurable
Hoisting Type	Winch trolley	Advanced hoist/winch	Electric hoist	Custom
Application	Steel mills	Heavy industry	Workshops	Flexible plants
Customization	Medium	Medium	Low	High
Safety Features	Full industrial	Enhanced safety	Standard	Optional

 

Key Features

Heavy-duty performance for continuous industrial use

Double girder design provides superior strength and stability

High lifting capacity up to hundreds of tons

Smooth and precise operation with advanced trolley system

Flexible control options (cab, remote, pendant)

Customizable configurations (span, height, attachments)

 

Lifting Capacity 5 – 500+ tons
Span 10.5 – 35.5 m
Lifting Height 6 – 30 m (customizable)
Working Duty A5 – A8 (heavy/continuous duty)
Ambient Temperature -20°C to +40°C
Control Mode Pendant / Remote / Cabin

1. Metal Structure (Bridge System)

 Main Girder (Double Beam)

Two box-type steel girders forming the main bridge

Made from high-strength steel (Q235/Q345)

Designed to تحمل very heavy loads with minimal deflection

This is the primary load-bearing structure of the crane

 

 End Carriages (End Trucks)

Located at both ends of the girders

Equipped with wheels, motors, and buffers

Enable crane movement along runway rails

Responsible for longitudinal travel of the crane

2. Hoisting Mechanism (Lifting System)

Winch Trolley

Runs on rails mounted on the main girders

Includes:

Electric motor

Gear reducer

Brake system

Drum with wire rope

Provides vertical lifting + horizontal trolley movement

 

 Hook Block Assembly

Forged hook with 360° rotation capability

Includes pulleys (sheaves) and safety latch

Available in single or double hook configuration

Directly handles the load during lifting

3. Traveling Mechanism

Crane Traveling System

Drives the entire crane along rails

Uses separate motor drives + gear systems

Ensures smooth, synchronized motion

Enables full workshop coverage

 

 

Trolley Traveling Mechanism

Moves trolley across the girders

Equipped with motorized wheels and guide rollers

Allows precise load positioning

4. Electrical System

Motors (lifting, trolley, traveling)

Control panels and PLC systems

Power supply (busbar or cable festoon)

Limit switches and sensors

Controls all crane operations and automation

5. Control System

Pendant control (wired)

Wireless remote control

Operator cabin (open/closed type)

Provides flexible and safe operation modes

 

6. Safety Devices

Overload protection limiter

Limit switches (hoisting & travel)

Emergency stop system

Anti-collision system

Buffers and rail sweepers

Motor overload protection

Ensures safe operation in heavy-duty environments

 

7. Auxiliary Components

Wheels (heat-treated forged steel)

Rail clamps & buffers

Cable festoon system

Maintenance platforms & ladders

Lighting and warning systems

Improve durability, maintenance, and usability

Bottom Line

The Heavy Duty QD Double Girder Overhead Crane is a modular system made up of robust structural components, precision lifting mechanisms, and advanced electrical controls.

Main girder + end carriage → structural backbone

Winch trolley + hook → lifting core

Motors + controls → operational intelligence

Safety systems → critical for industrial reliability

Sketch

Main technical

 

 

1. High Lifting Capacity

Capable of handling 5 to 500+ tons

Ideal for extremely heavy materials such as steel coils, slabs, and machinery

• Perfect for industries requiring large-scale material handling

 

2. Superior Structural Strength

Double girder (box-type) design ensures:

High rigidity

Minimal deflection

Long-term durability

• Provides stable and reliable lifting performance

 

3. Heavy-Duty & Continuous Operation

Designed for A5–A8 duty classes

Suitable for 24/7 continuous operation

• Excellent for steel mills and high-production environments

 

4. Smooth and Precise Operation

Equipped with:

Advanced winch trolley system

Variable frequency drives (optional)

• Enables accurate positioning and reduced load swing

 

5. Wide Working Coverage

Large span and lifting height

Covers entire workshop or production line

• Reduces need for multiple lifting systems

 

6. High Safety Standards

Includes:

Overload protection

Limit switches

Emergency stop

Anti-collision systems

• Ensures safe operation in hazardous environments

 

7. Customizable Design

Can be tailored for:

Span, lifting height

Special attachments (grab, magnet, ladle hook)

Automation and smart control

• Fits specific industrial requirements

 

8. Long Service Life & Low Maintenance

Robust components and heavy-duty design

Reduced wear under continuous operation

• Provides high return on investment (ROI)

 

1. Steel Mills & Metallurgy Plants

Handling:

Molten metal (ladle cranes)

Steel billets, slabs, coils

Used in:

Blast furnaces

Continuous casting lines

• Core equipment in steel production

 

2. Heavy Manufacturing Industry

Moving large machinery and components

Assembly line material handling

• Essential for machinery and equipment production

 

3. Foundries

Transporting molten metal and castings

Operating in high-temperature environments

• Requires heat-resistant configurations

 

4. Shipbuilding & Marine Industry

Lifting:

Ship sections

Engines and heavy components

• 👉 Used in shipyards and dockyards

 

5. Power Plants

Handling turbines, generators, and heavy equipment

Maintenance and installation tasks

• Critical for power generation infrastructure

 

6. Warehouses & Logistics (Heavy Duty)

Handling oversized and heavy cargo

Indoor bulk material movement

• Improves efficiency in large storage facilities

 

7. Mining & Construction

Transporting heavy raw materials and equipment

Supporting construction of large structures

• Suitable for rugged industrial environments

 

The production process of a QZ Series Double Girder Grab Bucket Overhead Crane involves several key stages, from initial design and material selection to assembly, testing, and final delivery. The manufacturing process is highly detailed and requires precise engineering to ensure the crane is durable, reliable, and capable of handling the heavy loads typical in bulk material handling applications. Below is a step-by-step overview of the production process:

 

1. Design and Engineering

Conceptual Design: The first step is designing the QZ Series crane based on the specific needs of the client or intended use. This involves discussions with the customer to understand the working environment, load capacity, span, lifting height, and control systems needed.

Detailed Engineering: Once the concept is finalized, engineers develop detailed designs for each component, including:

The bridge frame (double girder structure).

The grab bucket (clamshell or orange peel).

Hoist mechanism and trolley systems.

Electrical control systems.

Safety features like overload protection and limit switches.

Structural Calculations: Engineers perform rigorous calculations to ensure the crane meets the required strength and stability standards, especially considering the heavy loads it will carry.

 

2. Material Selection

High-Quality Steel: Materials used in the crane are typically high-strength steel, which provides durability and safety under heavy loads.

Steel Plates for Girder Frame: Used to fabricate the main bridge girder and cross beams.

Steel for Trolley and Hoist: The trolley and hoist components require materials with high wear resistance and structural strength.

Grab Bucket Materials: The grab bucket is usually made from high-strength steel or alloy steel for durability, especially when handling abrasive materials.

Motors and Electrical Components: For the hoisting mechanism, trolley, and control systems, the motors and electrical components must be of high quality to ensure efficient and reliable operation.

 

3. Manufacturing and Fabrication

CNC Cutting and Welding:

Steel plates are cut using CNC cutting machines to the precise dimensions needed for each part (such as the girder beams, frame structure, and support brackets).

Welding is done to join these components into larger structures like the double girder frame and trolley frame. Precision welding techniques are used to ensure the parts are strong and properly aligned.

Machining: Parts like hoist drums, shaft supports, and gears are machined to meet exact specifications, ensuring smooth and reliable movement.

Casting and Forging:

Some critical parts, like gears, bearings, and certain components of the grab bucket, may be cast or forged to achieve the necessary strength and resistance to wear.

Grab Bucket Fabrication:

The grab bucket is often assembled separately, with the clamshell jaws or orange peel claws welded and fitted with the hydraulic or mechanical controls that open and close the grab.

The bucket is then tested to ensure proper functioning before being integrated with the hoist mechanism.

 

4. Assembly

Girder Assembly: The two girders that make up the double girder design are assembled and aligned. These are the primary load-bearing components, and the alignment must be precise to ensure smooth crane operation.

Trolley and Hoist Assembly:

The trolley is attached to the bridge frame and is fitted with the hoisting mechanism.

The hoist (which includes the drum, ropes, and lifting motor) is installed on the trolley to lift and lower the grab bucket.

The trolley wheels are mounted to ensure smooth horizontal movement along the girder.

Grab Bucket Installation: The grab bucket is mounted on the hoist ropes and integrated with the hoist system. Depending on the crane design, hydraulic or electric motors control the opening and closing of the grab.

End Carriages and Wheels: The end carriages are assembled and fitted with wheels, which allow the entire crane to travel along the runway rails. These carriages are essential for smooth movement.

 

5. Electrical and Control Systems Installation

Electrical Wiring: The crane's electrical systems (motors, limit switches, lights, etc.) are installed, and all wiring is tested to ensure it meets safety standards.

Control Panel Assembly:

The operator control panel (if a cabin is used) or wireless remote controls are installed.

The PLC (Programmable Logic Controller) is programmed to automate and control the crane's movements, ensuring smooth operation with precise control over lifting, lowering, and horizontal travel.

Safety Systems: The crane's safety features (e.g., overload protection, limit switches, emergency stop buttons, wind monitoring systems) are tested and configured.

 

6. Painting and Finishing

Surface Treatment: The crane components are typically subjected to surface treatment processes like shot blasting or sandblasting to remove rust and debris.

Painting: After surface treatment, the crane components are painted with high-quality industrial paint that provides protection against corrosion, especially in outdoor or harsh environments.

Coating for Grab Bucket: The grab bucket is also coated to resist corrosion, especially if it's going to be used in wet or highly abrasive environments like ports or steel plants.

 

7. Testing and Quality Control

Pre-Assembly Testing: Individual components like the hoist mechanism, grab bucket, and electrical systems are tested for functionality before final assembly.

Full System Testing:

The completed crane undergoes a series of rigorous tests, including:

Load tests to ensure the crane can handle the specified weight without any issues.

Safety system checks to verify that all limit switches, emergency stops, and overload protection devices are working properly.

Operational tests for both manual and automatic control systems to ensure smooth operation and correct functionality of all movements (lifting, lowering, horizontal travel, etc.).

Final Inspection: Once testing is complete, the crane is subjected to a final quality control check to ensure everything meets the design and safety standards.

 

8. Packaging and Delivery

Disassembly (if needed): Some larger cranes may be disassembled for easier transport. Components like the girder, trolley, and grab bucket may be separated into smaller sections.

Packaging: Smaller parts and sensitive components are carefully packaged to avoid damage during transport.

Shipping: The crane is shipped to the customer's site, either as a pre-assembled unit or in parts that will be reassembled onsite. The delivery includes documentation, installation instructions, and warranty details.

 

9. Installation and Commissioning

Once the crane arrives at the customer's site, installation is carried out by trained technicians, who will:

Assemble any parts that were disassembled during transport.

Install the crane on the runway rails and connect the electrical systems to the power supply.

Commissioning involves running the crane through a series of test operations to ensure everything is working as expected before being handed over for regular use.

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%.