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OVERHEAD CRANE SELECTION GUIDE

Single Girder vs Double Girder Overhead Crane

The girder count is not a badge of quality. It is a structural choice that affects bridge weight, trolley arrangement, hook height, runway reactions, maintenance access and project cost.

Double girder overhead crane with a top-running trolley in a workshop.

The Short Answer

For a conventional workshop crane, single girder is often the sensible starting point when loads and duty are moderate. Double girder becomes attractive when the project needs a heavier trolley, greater hook height, a long span, frequent operation, maintenance walkways, auxiliary hoists or process-specific equipment. Neither answer should be selected from rated capacity alone.

Single Girder Overhead Crane

One bridge girder carries an under-slung electric hoist or low-headroom hoist. The lighter bridge generally reduces dead weight and wheel reactions, which can help when the runway or building structure has limits.

Double Girder Overhead Crane

Two bridge girders support a top-running trolley or open-winch trolley. The layout gives engineers more freedom for heavy loads, demanding duty, walkways, cabins, auxiliary hooks and special lifting devices.

What Actually Decides the Girder Layout

A useful comparison starts with the lifting task and the building. These six checks usually expose the trade-offs before a quotation is prepared.

Load and Load Spectrum

Record the maximum load, typical load and any lifting beam, magnet or grab weight. Frequent near-capacity lifts matter more than a headline tonnage.

Span and Bridge Stiffness

Longer spans increase bridge deflection and wheel-load effects. A double girder bridge can provide more stiffness, but the result must be engineered for the actual span.

Hook Height and Approach

Check roof clearance, runway elevation, hook path and end approach. Hoist and trolley geometry can matter as much as the number of girders.

Duty and Travel Frequency

Daily cycles, travel distance, starts per hour and load spectrum determine duty. Both layouts can be engineered, but demanding service often needs the flexibility of double girders.

Runway and Building Loads

Bridge dead weight, trolley position and dynamic effects change wheel reactions. The building engineer should review crane data before the runway is finalized.

Maintenance and Special Equipment

Walkways, service platforms, cabins, dual hoists and process attachments need space. A double girder arrangement usually accommodates these options more readily.

Duty classification deserves its own check. See the A3 vs A5 overhead crane duty class guide before comparing two quotations that use different service assumptions.

Single Girder vs Double Girder Comparison

The table below describes common design tendencies, not fixed capacity limits. Crane series, span, duty, hoist arrangement and local standards can change the answer.

Decision point

Single girder

Double girder

Bridge and hoist arrangement

Single girder:
One bridge girder, usually with an electric hoist travelling on the lower flange.

Double girder:
Two bridge girders, usually with a top-running trolley or open-winch trolley.

Typical project fit

Single girder:
General manufacturing, warehouses, assembly areas and moderate production duty.

Double girder:
Heavy manufacturing, long spans, high duty, process cranes and special lifting systems.

Hook height

Single girder:
Can be efficient with a low-headroom hoist, but girder and hoist depth influence the upper hook position.

Double girder:
The trolley can place the hook between the girders, often improving available lifting height.

Bridge weight and runway reactions

Single girder:
Generally lower dead weight for the same basic task, subject to span and design.

Double girder:
Generally heavier; runway reactions and supporting steel need careful coordination.

Duty and operating intensity

Single girder:
Well suited to light and medium production duty when the hoist and bridge are correctly selected.

Double girder:
Offers more flexibility for high-frequency travel, heavy trolleys and demanding process duty.

Maintenance access

Single girder:
Simpler bridge with fewer access features; maintenance is commonly performed from approved access equipment.

Double girder:
Can include walkways, platforms and easier trolley access when the project requires them.

Special configurations

Single girder: Low-headroom hoists, coordinated dual hoists and custom controls are possible when the bridge, total capacity and working duty remain suitable. For long loads that need two lifting points, review the single girder overhead crane with dual hoists and confirm load sharing, hook spacing and control mode.

Double girder:
Better suited to cabins, auxiliary hooks, dual trolleys, open winches and large lifting attachments.

Project cost

Single girder:
Often lower for comparable load, span, duty and scope because the bridge is lighter and simpler.

Double girder:
Higher initial cost can be justified by hook height, duty, access or special equipment requirements.

A 10 Ton Example

A 10 ton crane in a short, lightly used maintenance bay may be a straightforward single girder project. The same rated load on a long runway, with frequent lifts near capacity, tight upper hook requirements and a maintenance walkway, may justify a double girder crane. The load marking is identical; the working condition is not.

When Each Layout Makes Sense

Use these as screening questions, then confirm the final bridge and hoist selection against drawings and operating data.

Start with Single Girder When

The application is general workshop or warehouse handling
Bridge dead weight and runway reactions need to stay modest
A standard or low-headroom electric hoist covers the hook path
Maintenance walkways, cabins and large auxiliary equipment are not required
The quotation priority is a practical, economical crane for defined duty

Start with Double Girder When

The load, span or operating frequency is demanding
Maximum hook height is critical to the process
A top-running trolley, open winch or auxiliary hook is needed
The crane needs walkways, service platforms, a cabin or special attachments
The project values process reliability and configuration freedom over minimum first cost

Data Needed for a Fair Comparison

Two quotations are only comparable when they use the same working condition. Send the following information before asking which girder layout costs less:

For a dual-hoist crane, also state the load on each hook, maximum hook spacing, whether the hoists run together or independently, and the permitted synchronization difference. These details can change the hoists, controls, bridge design and final price even when the total rated load is unchanged.

Maximum load and typical load, including lifting attachments
Span, runway length and required lifting height
Building section showing roof, runway and obstruction clearances
Operating cycles, travel distance and expected duty
Indoor or outdoor environment, temperature and dust or corrosion conditions
Power supply, control preference and required travel speeds
Walkway, cabin, auxiliary hook or special process requirements

The overhead crane buying guide explains how these inputs affect the complete system, not only the bridge.

Frequently Asked Questions

Is a double girder overhead crane always stronger?

Not automatically. Both layouts are engineered for a rated load, span and duty. Double girders provide more structural and trolley-layout flexibility for heavy or demanding service, but the final capacity comes from the complete design.

Can a 10 ton overhead crane use a single girder?

Often, yes. A 10 ton single girder crane can be practical when the span, duty, hook height, runway and building clearances support it. Frequent near-capacity lifts or a demanding process may point to a double girder layout.

Which layout gives more lifting height?

A double girder top-running trolley can place the hook between the girders and often improves hook height. Low-headroom single girder hoists can also work well. The roof level, runway elevation and hoist geometry must be checked together.

Which crane usually has the lower initial cost?

For comparable load, span and duty, a single girder bridge is usually lighter and simpler. That often lowers crane and supporting-structure cost. The comparison is only meaningful when both quotations use the same duty, speeds and scope.

What information is needed before selecting the layout?

Provide the maximum load, typical load, span, lifting height, runway length, duty or operating cycles, building clearances, power supply, control method and any special attachments or maintenance-access requirements.

Compare the Crane Around Your Building

Share the load, span, hook height, runway and operating cycle. SUNFACRANE will explain which layout fits the duty and where the main cost and building-load differences come from.