Single Girder vs Double Girder Crane — What’s the Difference?

A Single Girder Crane has one main beam with the hoist suspended underneath. It typically supports loads from 0.5–20 tons, with a span up to 20 meters. It is more cost-effective and suitable for general industrial applications.

A Double Girder Crane has two parallel beams with the hoist running on top. It supports heavier loads from 5–500+ tons, offers a wider span, and is designed for higher duty cycles, making it ideal for heavy-duty and industrial operations.

Structural Differences

Single Girder Crane
Consists of a single girder spanning between two end carriages. The hoist is mounted on an under-running trolley, traveling beneath the beam. This design is more compact, lighter, and cost-efficient.

Double Girder Crane
Consists of two parallel girders. The hoist is mounted on a top-running trolley, traveling on top of the beams. This structure is significantly stronger and allows for higher load capacity and wider spans.

Comparison Table: Single Girder vs Double Girder

Single Girder Crane — In Detail

Advantages:

• Lower cost (less material and simpler structure)
• Lightweight (less demand on building structure)
• Low headroom (ideal for low ceiling buildings)
• Easier installation and relocation
• Simple maintenance

Disadvantages:

• Limited capacity (typically ≤ 20 tons)
• Limited span (deflection increases with longer spans)
• Lower duty cycle (not ideal for 24/7 operation)
• Lower hook height (hoist under beam reduces lifting height)

Best for:

• Assembly lines
• Maintenance workshops
• Medium-sized warehouses
• Food & pharmaceutical plants (stainless options)
• Buildings with limited structural capacity

Double Girder Crane — In Detail

Advantages:

• High load capacity (up to hundreds of tons)
• Wider span with less deflection
• High duty cycle (M6–M8, suitable for 24/7 operation)
• Greater hook height (hoist runs on top)
• Supports cabin, grab, magnet, and special equipment
• More durable in harsh environments

Disadvantages:

• Higher cost
• Heavier (requires stronger building structure)
• Requires more headroom
• More complex maintenance

Best for:

• Steel mills and foundries
• Shipyards
• Heavy fabrication plants
• Power plants and energy facilities
• Ports and terminals
• Any application requiring >20 tons or >20 m span

How to Choose — 5-Step Guide

Step 1: Define Maximum Load
Add a safety factor of 25–33% to actual load.
Example: 10 tons → choose 12.5–13.3 tons
If >20 tons → choose Double Girder

Step 2: Measure Span

• < 15 m → Single Girder is sufficient
• 15–20 m → depends on load and duty cycle

• 20 m → Double Girder recommended

Step 3: Evaluate Duty Cycle

• 1–4 hrs/day → M3–M4 (Single)
• 4–8 hrs/day → M4–M5 (Single or Double)
• 24/7 operation → M6–M8 (Double only)

Step 4: Check Required Hook Height
If maximum lifting height is critical → Double Girder has advantage

Step 5: Check Building Structure
Double Girder cranes are 2–3 times heavier. Structural verification is required.

Frequently Asked Questions (FAQ)

Q: Can a Single Girder Crane lift 20 tons?
A: Yes, but it depends on span. For 20 m span and 20 tons, special design is required. In many cases, Double Girder may be more practical.

Q: Can I upgrade from Single to Double Girder later?
A: Possible, but costly and complex. Runway rails and structure often need modification. Proper planning from the beginning is recommended.

Q: Can ALLA design both types?
A: Yes. ALLA provides design, manufacturing, installation, and maintenance for both Single and Double Girder cranes based on customer requirements.

Q: What is the price difference?
A: Double Girder cranes are typically 40–80% more expensive than Single Girder cranes of the same capacity due to more materials and complexity.