A Type Box Type Double Girder Gantry Crane

 

An A-Type Box Type Double Girder Gantry Crane is a heavy-duty gantry crane commonly used in outdoor yards and large industrial sites. Here's a clear breakdown of what the term means and what the crane is used for:

What the Name Means

A-Type
The crane legs are shaped like the letter "A", giving strong lateral stability and allowing better load distribution.

Box Type
The main girders and legs use box-section welded steel structures, which provide:

High strength and rigidity

Better resistance to bending and torsion

Reduced vibration under heavy loads

Double Girder
Two main girders support the trolley, allowing:

Higher lifting capacity

Greater lifting height

Better stability for heavy or wide loads

Gantry Crane
The crane runs on ground rails (not fixed to a building), making it ideal for outdoor or semi-outdoor operations.

 

A-Type vs. L-Type (Straight Leg) Gantry

Parameter	A-Type Gantry	L-Type Gantry
Lateral Stability	★★★★★ (Excellent)	★★★☆☆ (Good)
Wind Resistance	★★★★★	★★★☆☆
Foundation Requirements	More horizontal component	Primarily vertical loads
Fabrication Complexity	Higher (more welds, angles)	Lower (simpler geometry)
Transportability	More challenging (bulkier)	Easier to transport
Clear Working Width	Slightly reduced by sloping legs	Full width available

 

A-Type vs. Semi-Gantry Crane

Aspect	A-Type Full Gantry	Semi-Gantry
Coverage Area	Full area under crane	One side against building
Installation Independence	Completely independent	Requires building support
Flexibility	Can be relocated	Fixed to building
Cost	Higher initial cost	Lower (uses existing structure)
Maintenance Access	All-around access	Limited on building side

 

TECHNICAL DATA SHEET EXAMPLE

Model: A-Type Gantry Crane A-50/35
Capacity: 50 metric tons (main hook)
Span: 35 meters (rail center to center)
Lifting Height: 18 meters (hook above rail)
Lifting Speeds:
Main hoist: 5 m/min (full load), 10 m/min (light load)
Auxiliary hoist: 15 m/min

Travel Speeds:
Crane travel: 20 m/min
Trolley travel: 15 m/min

Duty Class: A6 (heavy duty, ~300 starts/hour)
Control System: Operator cabin with ergonomic controls
Power Supply: 380V, 3-phase, 50Hz, 200A supply

 

An A-Type Box Type Double Girder Gantry Crane consists of several major structural, mechanical, and electrical components. Below is a clear, industry-standard breakdown of its components:

1. Main Structural Components

1.1 Main Girders (Double Girder – Box Type)

Two welded box-section girders

Support the hoisting trolley

Designed for high rigidity and minimal deflection

.

1.2 Gantry Legs (A-Type)

Two A-shaped rigid legs (or one rigid + one hinged, depending on design)

Transfer loads to the ground rails

Provide lateral and longitudinal stability

 

1.3 End Carriages (Traveling Trucks)

Located at the bottom of the legs

Contain:

Traveling wheels

Bearings

Axles

Enable crane long-travel motion

1.4 Ground Rail System

Steel rails fixed on concrete foundations

Guide crane movement along the yard

2. Lifting Mechanism

2.1 Hoisting Trolley

Mounted on top of the double girders

Travels transversely along the crane span

2.2 Hoist Unit

Includes:

Hoist motor

Gearbox

Wire rope drum

Wire ropes

Hook block (or spreader/grab/magnet)

 

3. Traveling Mechanisms

3.1 Crane Traveling Mechanism (Long Travel)

Motors and gearboxes mounted on end carriages

Drives the crane along ground rails

3.2 Trolley Traveling Mechanism (Cross Travel)

Motor and reducer drive the trolley across the girders

 

4. Electrical System

4.1 Power Supply System

Cable reel system or conductor bar

Supplies power to crane traveling mechanism

4.2 Control System

PLC or relay-based control

Control options:

Cabin control

Pendant control

Remote control

4.3 Electrical Panels

Main control cabinet

Protection devices (MCB, overload relays, contactors)

5. Safety Devices

Overload limiter

Limit switches (hoisting, traveling)

Emergency stop

Rail clamps / wind clamps

Buffer stops

Anti-collision system

Anemometer (wind speed sensor – outdoor cranes)

.

6. Operator Facilities

6.1 Operator Cabin (Optional)

Air-conditioned cabin

Ergonomic control console

Safety glass

6.2 Access Systems

Ladders

Platforms

Handrails

7. Auxiliary Components

Festoon cable system

Lighting system

Warning alarms

Maintenance platforms

Paint and corrosion protection system

Sketch

 

 

 

1. High Load Capacity

Double girder and box-type construction provide excellent strength

Capable of handling heavy and ultra-heavy loads

Suitable for high duty cycles (FEM / ISO heavy-duty classes)

2. Superior Structural Stability

A-type leg design offers strong lateral stability

Box-section girders reduce deflection and vibration

Safe operation even with wide or off-center loads

3. Large Span and Lifting Height

Easily designed for large spans and high lifting heights

Ideal for handling oversized components

4. Excellent Outdoor Performance

Designed to withstand wind loads and harsh weather

Can be equipped with wind clamps, rail clamps, and anemometers

Long service life in outdoor environments

5. High Operational Efficiency

Smooth and precise lifting and traveling motions

Faster material handling improves productivity

Compatible with automation and remote control systems

6. Versatile Load Handling

Can be fitted with:

Hook

Grab bucket

Electromagnet

Spreader beam

Adaptable to multiple industries and materials

7. Easy Maintenance

Box-type structure allows easy inspection

Durable components reduce maintenance frequency

Standardized spare parts availability

 

1. Shipyards and Ports

Handling ship sections and heavy marine components

Container and cargo handling in open yards

2. Steel Mills

Transporting steel coils, plates, billets, and slabs

Suitable for high-temperature and heavy-duty operations

3. Power Plants

Installation and maintenance of turbines and generators

Handling heavy equipment during construction

4. Precast Concrete Yards

Lifting beams, slabs, pipes, and columns

Efficient movement of large concrete elements

5. Construction and Infrastructure Projects

Handling bridge segments and large structural components

Used in metro, highway, and bridge construction yards

6. Heavy Manufacturing Industries

Assembly and handling of heavy machinery

Equipment fabrication and storage yards

7. Mining and Material Stockyards

Handling bulk materials with grabs or magnets

Reliable performance in dusty and rough environments

 

1. Engineering Design & Planning

Load calculation (SWL, impact, wind, seismic)

Span, lifting height, and duty class determination (ISO / FEM / CMAA)

Structural design of box girders and A-type legs

Selection of hoisting, traveling, and electrical components

Preparation of:

General arrangement drawings

Fabrication drawings

Electrical schematics

Design review and customer approval

2. Raw Material Procurement & Inspection

Procurement of structural steel plates and profiles

Inspection of:

Material grade and thickness

Mill test certificates (MTC)

Storage under controlled conditions to prevent corrosion

3. Steel Cutting & Preparation

CNC flame cutting / plasma cutting of steel plates

Edge preparation for welding

Shot blasting for surface cleanliness (Sa 2.5 standard)

Marking and identification of components

4. Box Girder Fabrication

Assembly of top plate, bottom plate, and side plates

Automatic submerged arc welding (SAW)

Camber control and deflection correction

Internal stiffener installation

Non-destructive testing (UT, MT)

5. A-Type Leg Fabrication

Fabrication of rigid and hinged legs (box structure)

Welding of bracings and stiffeners

Machining of connection plates

Dimensional inspection and NDT testing

6. End Carriage Manufacturing

Fabrication of end carriage frames

Installation of:

Wheels

Bearings

Axles

Alignment and load distribution checks

7. Machining & Assembly of Mechanical Components

Machining of:

Wheel seats

Shaft holes

Connection surfaces

Assembly of:

Hoist unit

Trolley frame

Gearboxes and couplings

8. Surface Treatment & Painting

Final shot blasting of all structural parts

Application of:

Primer coat

Intermediate coat

Finish coat

Paint thickness inspection (DFT)

Corrosion protection per environment class

9. Electrical System Installation

Installation of motors, brakes, and limit switches

Wiring of control panels and junction boxes

Installation of:

Cable festoon or conductor bars

Control cabin or remote control system

Electrical continuity and insulation testing

10. Pre-Assembly & Factory Trial

Trial assembly of main girders, legs, and end carriages

Alignment and dimensional verification

No-load functional testing:

Hoisting

Trolley travel

Crane travel

11. Load Testing & Quality Inspection

Static load test (125% of rated load)

Dynamic load test (110% of rated load)

Safety device testing

Final inspection per standards

12. Dismantling, Packing & Dispatch

Dismantling into transportable sections

Protective packing for long-distance shipment

Documentation preparation:

Test certificates

Quality reports

Operation & maintenance manuals

13. Site Installation & Commissioning (Optional)

Rail alignment verification

Crane erection and bolting

Electrical connection and system calibration

Final load testing and handover

 

 

 

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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