MZ Type Double Girder Grab Gantry Crane

 

Why Choose MZ Double Girder Grab Gantry Crane?

Heavy-duty performance: Handles the toughest bulk materials.

Adaptability: Works in ports, power plants, mines, and more.

Future-proof: Upgradable to smart automation.

 

The MZ type double girder grab gantry crane is the best choice for heavy-duty bulk material handling, offering higher capacity, stability, and automation potential compared to single-girder models. It is widely used in ports, power plants, steel mills, and mining operations.

 

Feature	MZ Double Girder Grab Crane	Bucket-Wheel Stacker	Mobile Harbor Crane
Material Type	Loose bulk (coal, ore, scrap)	Continuous bulk	Containers + bulk
Load Capacity	Up to 500 tons	Limited by conveyor	Up to 200 tons
Mobility	Rail/Rubber-tired	Rail-only	Rubber-tired
Automation	Yes (semi/full-auto)	Fully automated	Manual/Semi-auto
Best For	High-volume stockyards	Large mines	General cargo ports

 

Lifting Capacity 5–100 tons (custom up to 500T)
Span 10–40m (adjustable)
Lifting Height 6–30m (depends on application)
Hoisting Speed 5–20 m/min (adjustable)
Trolley Speed 20–40 m/min
Gantry Travel Speed 20–60 m/min
Power Supply 380V/50Hz (or customized)
Control Mode Pendant / Wireless Remote / Full Auto
Working Class A5–A7 (medium to heavy duty)
Ambient Temp. -20°C to +50°C (arctic/heat options)

 

The MZ type double girder grab gantry crane is a heavy-duty lifting system designed for bulk material handling. Below is a detailed breakdown of its core components, categorized by structural, mechanical, electrical, and safety systems:

 

1. Main Structural Components

A. Double Girder Bridge

Two welded steel box girders (Q345B steel, corrosion-treated)

End carriages with rail wheels (for movement along tracks)

Stiffeners & reinforcements to prevent deflection under heavy loads

B. Support Legs & End Frames

Fixed or adjustable legs (height customization)

Cross beams for lateral stability

Buffers & bumpers (shock absorption at travel limits)

C. Rail/Track System

Heavy-duty crane rails (QU80/QU100) embedded in concrete

Rail clamps (to lock crane during high winds)

Fishplates & fasteners for rail joint connections

 

2. Lifting & Grabbing Mechanism

A. Grab Bucket Assembly

Clamshell grab (for coal/grain) or multi-jaw grab (for scrap/rocks)

Rope/Wire rope drum (for grab opening/closing)

Sheaves & pulleys (stainless steel for wear resistance)

 

B. Hoisting System

Main hoist (for lifting/lowering grab)

Drum & wire rope (ISO 4308 standard)

Geared motor (AC/DC, with brake)

Auxiliary hoist (for grab control)

C. Trolley System

Motorized trolley (runs along girder)

Wheels & bearings (for smooth travel)

Reducer & drive motor (VFD-controlled)

3. Drive & Travel Mechanism

A. Gantry Travel Drives

4-wheel drive system (one motor per leg)

Travel wheels (forged steel, heat-treated)

Anti-skid devices (for wet/icy conditions)

B. Power Transmission

Festoon system (for electric power/data cables)

Cable reels (for rubber-tired mobile versions)

4. Electrical & Control Systems

A. Power Supply

Main power cabinet (IP55 protection)

Distribution panels (circuit breakers, contactors)

B. Control Systems

Pendant control station (IP65-rated)

Wireless remote control (2.4GHz frequency)

PLC automation (for programmed grabbing cycles)

C. Sensors & Monitoring

Load limiter (20-ton to 500-ton capacity)

Wind speed anemometer (auto-shutdown at >20m/s)

Limit switches (for hoisting/travel end positions)

.

5. Safety Components

Emergency stop buttons (on pendant + remote)

Anti-collision system (laser/UWB sensors)

Overload protection (mechanical + electronic)

Lightning arrestor (for outdoor installations)

6. Optional Add-Ons

Weighing system (digital load cells)

Automatic lubrication system (for bearings/wires)

Heated panels (for sub-zero operations)

CCTV cameras (for blind-spot monitoring)

SKETCH

Main technical

 

1. High Load Capacity & Stability

Double girder design provides superior strength, enabling 5–500-ton lifting capacity (vs. single girder's 20-ton limit).

Minimal deflection even at maximum span (40m+), ideal for heavy bulk materials like coal, ore, and scrap metal.

2. Efficient Bulk Material Handling

Motorized grab bucket (clamshell/multi-jaw) enables fast loading/unloading (2–3x faster than excavators).

Dual-hoist system (main + auxiliary) ensures precise grab control for dense or sticky materials.

3. Durability for Harsh Environments

Corrosion-resistant coatings (galvanized/epoxy) withstand saltwater, dust, and humidity.

Wind-resistant features: Rail clamps, anemometers (auto-lock at >20 m/s wind speeds).

4. Flexible Mobility Options

Rail-mounted: Smooth operation on fixed tracks (ports, stockyards).

Rubber-tired: Mobile for temporary sites (construction, mining).

5. Advanced Control & Automation

Wireless remote/PLC control reduces labor costs.

Automated stockyard systems integrate with IoT for real-time inventory management.

6. Cost-Effective Operation

Lower energy consumption vs. continuous bucket-wheel systems.

Minimal maintenance: Sealed bearings, automatic lubrication options.

 

1. Ports & Shipping Terminals

Unloading bulk carriers: Coal, iron ore, grain from ships to trucks/conveyors.

Stockpile management: Stacking/reclaiming materials in open yards.

2. Power Plants

Coal handling: Transporting fuel from storage to boiler feed systems.

Ash disposal: Moving fly ash to silos or trucks.

3. Steel & Cement Industries

Raw material handling: Limestone, clinker, slag.

Scrap processing: Sorting and loading shredded metal.

4. Mining & Quarries

Bulk loading: Crushed stone, sand, gravel onto trucks/trains.

5. Grain & Fertilizer Storage

Efficient transfer: Wheat, corn, urea between silos, ships, or trucks.

6. Waste Recycling

Scrap yards: Handling and sorting non-ferrous metals, car bodies.

 

 

1. Design and Planning

Demand Analysis: According to customer needs and usage scenarios, a detailed demand analysis is carried out to determine the specifications, load, span, lifting height, etc. of the crane.

Engineering Design: Engineers use CAD and other design software to carry out detailed design, including structural, mechanical, electrical and other aspects to ensure that the design meets relevant standards and specifications.

2. Material Procurement

Material Selection: Select appropriate steel, motors, control systems and other components according to design requirements.

Supplier Screening: Screen suppliers of materials and components to ensure the quality and reliability of materials.

3. Processing and Manufacturing

Cutting and Forming: Cut, weld, bend and other processes on steel to form main beams, end beams and other structural components.

Machining: Precision machining of key components, such as turning, milling, drilling, etc., to ensure that the size and accuracy meet the design requirements.

Surface Treatment: Spray, galvanize or rust-proof metal parts to enhance corrosion resistance and aesthetics.

4. Assembly

Component Assembly: Assemble the main beam, end beam, trolley, lifting mechanism and other components to form a complete crane structure.

Installation of electrical system: Install electrical equipment such as motors, control cabinets, sensors, limit switches, etc. to ensure the normal operation of the electrical system.

5. Debugging and testing

Preliminary debugging: Carry out preliminary debugging of the crane to check the coordination and operation of each component.

Load test: Carry out load test to ensure the safety and stability of the crane under rated load, and test the functions of safety devices such as overload protection and limit switches.

Performance test: Test the performance indicators of the crane such as lifting speed, running speed, braking effect, etc. to ensure that they meet the design requirements.

6. Quality inspection

Quality inspection: Carry out a comprehensive quality inspection of the crane, including appearance, size, performance, etc., to ensure compliance with relevant standards.

Safety assessment: Carry out safety assessment to ensure the normal operation of all safety devices and systems.

7. Delivery and installation

Packaging and transportation: Pack qualified cranes and prepare them for transportation to the customer site.

On-site installation: Carry out on-site installation according to customer requirements, including basic production and equipment debugging.

Training and handover: Train operators to ensure that they master the operation methods and safety precautions of the equipment and complete the handover work.

 

 

 

 

 

 

 

Material Inspection

Quality Inspection: Strict quality inspection is carried out on the purchased raw materials to ensure that they meet the design requirements and national standards.

Material Storage: Qualified materials are stored according to classification to prevent corrosion or damage.

Cutting and Forming

Steel Cutting: Use plasma cutting, laser cutting or flame cutting and other technologies to cut the steel according to the size of the design drawing.

Forming Processing: Form the steel plate through bending, rolling, welding and other processes to manufacture the main beam, end beam and other structural parts.

Welding

Component Welding: The cut and formed steel parts are welded into the main structures such as the main beam, end beam and trolley. The welding process needs to be strictly controlled to ensure the structural strength and welding quality.

Weld Inspection: Use non-destructive testing technology (such as ultrasonic testing, radiographic testing) to inspect the welds to ensure that there are no cracks or other defects.

Machining

Precision Machining: Precision machining is performed on the key components of the crane, such as wheel sets, bearing seats, pulleys, etc., to ensure their dimensional accuracy and surface quality.

Assembly of the whole machine

General assembly: On the basis of pre-assembly, the overall assembly of the crane is carried out, including the final installation of the main beam, end beam, lifting mechanism, walking mechanism, etc.

Commissioning and testing

Under dynamic conditions, the operating performance of the crane is tested, including the testing of lifting, walking, steering and other functions. The overall size of the assembled bridge crane is checked to ensure that all dimensions meet the design requirements.

Spraying and anti-corrosion treatment

Surface treatment Rust removal: Rust removal on the surface of the crane, common methods include sandblasting, pickling, etc. Primer spraying: Spray anti-corrosion primer on the treated surface to prevent metal oxidation and corrosion. Topcoat spraying Color spraying: Spray topcoat according to customer requirements or industry standards to give the crane a protective and decorative effect. Marking: After spraying, mark the crane's identification information in accordance with the specifications, such as model, rated load, etc.

Factory and installation

Packaging and transportation

Packaging protection: Protectively package the key components of the crane to prevent damage during transportation. Transportation arrangement: According to the equipment size and transportation conditions, select a suitable transportation method to transport the crane to the customer's site.

Acceptance and delivery

Customer acceptance

On-site acceptance: The customer conducts on-site acceptance of the crane according to the contract requirements and technical specifications to check the performance and quality of the equipment.

Problem rectification: If any problems are found, the manufacturer needs to rectify them in time to ensure that the equipment fully meets the customer's requirements. Delivery and use Operation training: The manufacturer usually trains the customer's operators to ensure that they can operate the crane correctly and safely.

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