What Is a Double Girder EOT Crane?

A double girder EOT (Electric Overhead Traveling) crane is a heavy-duty lifting system featuring two parallel bridge girders that support the trolley and hoisting mechanism. These industrial workhorses are the preferred choice when you need:

• Higher lifting capacities (typically 10-550 tons)
• Longer spans (up to 35 meters)
• Heavier duty cycles (Class A4-FEM to Class A6-FEM)
• Additional features like walkways, maintenance platforms, or auxiliary hoists

At Dongqi Crane, we engineer double girder cranes with optimized steel structures that provide superior hook height compared to single girder alternatives.

In-Depth Technical Explanation

A Double Girder Electric Overhead Traveling (EOT) crane is a heavy-duty material handling system consisting of two parallel load-bearing beams (girders) that form the bridge structure, supported by end trucks that travel along elevated runway rails. This configuration provides distinct mechanical advantages that make it the preferred solution for demanding industrial applications.

Core Structural Characteristics:

1. Twin-Girder Configuration

• Comprises two main girders (typically box-type or truss design)
• Spacing between girders ranges from 1.2m to 3.5m depending on capacity
• Connected by rigid cross members at regular intervals (usually 4-6m)

1. Load Path Mechanics

• Vertical loads transfer through:
  1) Hoist → Trolley → Girder flanges
  2) Girders → End trucks → Runway beams
• Lateral forces absorbed by girder web stiffeners
• Torsional loads resisted by closed box-section design

Key Advantages Over Single Girder Designs:

A. Enhanced Load Capacity (Typical Ranges)

Industry	Capacity Range
General Manufacturing	10-50t
Steel Mills	50-250t
Heavy Fabrication	250-550t

B. Superior Hook Height

• Additional 15-30% clear space under the crane
• Achieved by mounting the hoist/trolley above girders (top-running)
• Critical for handling tall loads like:
  • Vertical pressure vessels
  • Wind turbine components
  • Industrial machinery

C. Improved Structural Performance

• 40-60% greater stiffness reduces deflection
• Typical deflection limits:
  • ≤ Span/800 (when loaded)
  • ≤ Span/1000 (for precision applications)
• Better dynamic stability during:
  • High-speed travel (up to 60m/min)
  • Load swinging conditions

D. Expanded Feature Integration

• Walkways for maintenance access (≥600mm width)
• Auxiliary hoist mounting points
• Specialized trolley designs:
  • Magnet trolleys with cable reels
  • Grab trolleys with dust-proofing
  • Rotating trolleys for coil handling

Technical Components Breakdown:

1. Girders

• Materials: Q235B/Q355B steel (standard), ASTM A572 (optional)
• Fabrication: Automated submerged arc welding (SAW)
• Stiffeners: Vertical (every 1.5m) and horizontal (top/bottom)

1. End Trucks

• Wheel configurations:
  • 4-wheel (≤50t)
  • 8-wheel (50-150t)
  • 16-wheel (>150t)
• Wheel loads: 10-60t per wheel

1. Drive Systems

• Travel drives: 3-phase AC motors (2-75kW)
• Control: Variable Frequency Drives (VFDs) for smooth acceleration

Dongqi Engineering Enhancements:

✔ Patented Girder Design – Corrugated web panels increase strength-to-weight ratio by 25%

✔ Smart Monitoring – Integrated strain gauges in critical sections provide real-time load data

✔ Modular Construction – Bolted connections allow for:

• Future capacity upgrades
• Easy transport to constrained sites

Industry-Specific Configurations:

For Steel Mills:

• Thermal protection (up to 200°C continuous)
• Ladle safety features:
• Redundant braking
• Anti-spill locking
• Temperature monitoring

For Power Plants:

• Seismic reinforcement (up to 0.3g)
• Specialized lifting attachments for:
• Turbine rotors
• Generator stators
• SCR catalysts

For Shipyards:

• Salt spray corrosion protection (C5-M class)
• Explosion-proof components (Zone 1/21)
• Dynamic load factor ≥1.25

This refined technical profile demonstrates why over 78% of heavy industrial facilities choosing Dongqi double girder EOT cranes achieve >99% operational availability in their first year of service. Our engineers can develop custom solutions meeting specific:

• Duty cycles (FEM 1.001 classification)
• Environmental conditions
• Automation requirements

Key Components: Understanding Crane Girders

What Is a Girder in a Crane?

The girder is the primary horizontal beam that:

• Forms the bridge structure
• Supports the trolley and load
• Transfers weight to end trucks

In double girder designs, two main girders run parallel with a stabilized connection system that:
✔ Increases rigidity by 40-60% vs single girders
✔ Reduces deflection under load
✔ Allows wider trolley wheel bases for better load distribution

Double Girder vs Single Girder EOT Cranes: Technical Comparison

Feature	Double Girder Crane	Single Girder Crane
Capacity	10-550+ tons	1-20 tons
Span	Up to 35m	Up to 28m
Hook Height	15-30% greater	Limited by girder depth
Duty Cycle	Heavy (A4-A6)	Light-Medium (A1-A3)
Trolley Type	Top-running	Underhung
Typical Applications	Steel mills, power plants, heavy fabrication	Workshops, warehouses

Pro Tip: Dongqi’s double girder cranes achieve 25% better fatigue life through patented welded box girder designs.

Double Girder EOT Crane Specifications

Our standard DQ-DG series includes these engineering benchmarks:

Structural Performance

• Deflection: ≤ Span/800 (loaded)
• Welding: 100% UT tested Class I welds
• Corrosion protection: ISO 12944 C4 coating system

Mechanical Systems

• Hoists: Modular design with 2/4/6 rope falls
• Brakes: Dual redundant fail-safe systems
• Travel drives: Frequency-controlled AC motors

Electrical Features

• Control: IP65 rated pendant + radio remote
• Protections: Overload, anti-collision, phase monitoring
• Optional: Automated positioning (±5mm)

Customization Options
✓ Explosion-proof versions (ATEX, IECEx)
✓ High-temperature adaptations (up to 60°C)
✓ Magnetic/grapple attachments

Why Choose Dongqi Double Girder Cranes?

1. Certified Quality

• CE, ISO 9001, GOST certified
• FEM 1.001/1.002 compliant

1. Performance Advantages

• 30% less energy consumption via regenerative drives
• 99.5% uptime guarantee

1. Smart Features

• IoT-enabled condition monitoring
• Predictive maintenance alerts

1. Global Support

• 2-year mechanical warranty

Industry-Specific Double Girder EOT Crane Solutions

1. Steel Industry Applications

Model Series: DQ-SG (Steel Grade)

• Ladle Handling Cranes
• Capacity: 50-450t
• Special Features:
  • Thermal protection (up to 300°C continuous)
  • Redundant brake systems (4 independent brakes)
  • Anti-spill locking mechanism
  • IR temperature monitoring system
  Typical Configuration:

  Main Hoist: 2x 250t (safety factor 2.5:1)  
  Aux Hoist: 50t (for slag pot handling)  
  Span: 28-34m  
  Duty Class: A7 (FEM 1.001)  

• Coil Handling Cranes
• Model Variants:
  • DQ-SG-CH: Standard coil handling
  • DQ-SG-RT: With rotating trolley (±180°)
  • DQ-SG-VT: Vacuum lifter version
  Technical Highlights:
• Non-marking nylon pads
• Automatic coil diameter adjustment
• C-hook weighing system (±0.5% accuracy)

2. Power Generation

Model Series: DQ-PG (Power Generation)

• Turbine Installation Cranes
• Precision requirements: ±2mm positioning
• Special Features:
  • Seismic design (up to 0.5g)
  • Micro-speed control (0.2-2m/min)
  • Anti-sway system
  Nuclear Plant Version:
• Radiation-resistant materials
• Seismic category I
• 72-hour emergency power
• Boiler Maintenance Cranes
  Key Parameters:
• Compact headroom design
• 360° rotating boom attachment
• Confined space operation package

3. Shipbuilding & Offshore

Model Series: DQ-SH (Shipyard Heavy Duty)

• Gantry Integration Cranes
• Capacity Range: 100-800t
• Special Configurations:
  • Salt spray protection (ISO 12944 C5-M)
  • Explosion-proof (ATEX Zone 1)
  • Dynamic load factor ≥1.5
  Hull Block Turnover Cranes:
• Dual trolley synchronization
• Automatic load balancing
• Anti-twist wire rope system

4. Automotive Manufacturing

Model Series: DQ-AM (Automotive Modular)

• Press Line Cranes
• Precision Features:
  • Laser guidance system
  • 0.1mm repeat positioning
  • Vibration isolation mounts
• Press Changeout Package:
  • Quick-disconnect tooling
  • 6-axis load monitoring
  • Automated alignment

5. Mining & Minerals

Model Series: DQ-MM (Mining & Minerals)

• Ore Handling Cranes
• Duty Enhancements:
  • Abrasion-resistant liners
  • Dust-proof IP65 components
  • 200% overload protection
  Hot Material Handling:
• Refractory insulation
• Heat shield packages
• Water-cooled grab options

6. Aerospace

Model Series: DQ-AS (Aerospace Special)

• Composite Handling Cranes
• Critical Features:
  • Non-sparking components
  • ESD protection
  • Cleanroom compatibility
• Wing Assembly Cranes:
  • 6-DOF positioning
  • Force feedback control
  • Composite-friendly tooling

7. Data Center Installation

Model Series: DQ-DC (Data Center)

• Server Rack Handling
• Precision Specs:
  • EMI/RFI shielded
  • 0.01° tilt monitoring
  • Vibration <0.5g
• Special Attachments:
  • Anti-static lifting beams
  • Server alignment guides
  • Rack stabilization system

Cross-Industry Comparison Table

Industry	Model Series	Unique Features	Typical Span	Duty Class
Steel	DQ-SG	Thermal protection, ladle safety	25-35m	A6-A8
Power	DQ-PG	Seismic design, micro-speed	20-30m	A4-A6
Shipyard	DQ-SH	Corrosion resistance, dynamic loading	30-50m	A7-A8
Automotive	DQ-AM	Precision positioning, quick-change	15-25m	A3-A5
Mining	DQ-MM	Abrasion protection, dust-proof	20-40m	A5-A7
Aerospace	DQ-AS	ESD protection, cleanroom	10-20m	A2-A4
Data Center	DQ-DC	Vibration control, EMI shielding	10-15m	A1-A3

Dongqi Custom Engineering Services:

• Industry-specific FEM calculations
• Application simulation testing
• Turnkey installation packages

For your specific application requirements, our engineers can:

1. Recommend optimal model series
2. Customize load-bearing configurations
3. Develop special attachments

Need help selecting the right double girder crane for your industry? Contact our application engineers for a free plant survey and solution proposal.

Technical Support:
📞 +86 18638815424
📧 sales010@cranesdq.com
🕒 24/7 emergency consultation available

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Dongqi provides:
✅ Free load analysis
✅ 3D layout drawings
✅ ROI calculation