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Crane TypeSemi-Gantry Crane
If one side already has a suitable building bracket, you don't need a second leg.
When it makes sense
If one side of the site already has a building, wall or bracket capable of carrying the crane rail, semi-gantry is the natural choice. The ground strip the second leg would have occupied stays free — a real gain on tight sites.
It also means less steel, a shorter runway and a simpler foundation.
What needs attention
In a semi-gantry crane the two rails sit on different structures: one on the ground, one on the building. The level difference and parallelism between these two rails needs closer tracking than on a full gantry, because the building can behave differently over time.
The building-side bracket must be structurally verified to carry both the vertical and horizontal crane loads.
Comparison with a full gantry
| Criterion | Full gantry | Semi-gantry |
|---|---|---|
| Support | Both legs on the ground | One leg on the ground, one side on the building |
| Building requirement | None | A load-bearing bracket/column is required |
| Site footprint | Two rail strips are occupied | One rail strip is occupied |
| Cost | Higher | More economical |
| Runway tracking | Both rails on the ground | Different structures — closer tracking needed |
| Suitability | The only option with no building | Advantageous with a suitable building |
Technical terms
| Term | What it means |
|---|---|
| Bracket girder | A beam extending out from a building column, carrying the runway. |
| Level difference | The height difference between the top surfaces of the two opposing rails. |
| Parallelism | How straight and evenly spaced the two rail lines are relative to each other. |
Frequently asked questions
Is my existing building's bracket suitable?
It's determined by calculating the column cross-section, the bracket connection and the foundation capacity. A visual assessment isn't enough — a structural check is required.
What happens if the building settles?
The level difference between the two rails changes, and the crane starts to strain. That's why runway measurement should be a fixed item on the maintenance schedule for a semi-gantry crane.