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:
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)
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)
Stiffeners: Vertical (every 1.5m) and horizontal (top/bottom)
End Trucks
Wheel configurations:
4-wheel (≤50t)
8-wheel (50-150t)
16-wheel (>150t)
Wheel loads: 10-60t per wheel
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:
