A semi gantry crane is the right choice when your building can carry one runway rail and you want one side of the floor kept clear. If the wall or column line cannot take the load, or the site is an open yard, a full gantry crane is the safer answer. Dafang supplies the semi gantry crane in two models: the BMH single-girder crane for 2–10 t and the BMG double-girder crane for 5–320 t.
Most buyers are stuck on three questions. Does my building qualify, since a semi gantry crane (also called a single-leg gantry crane or half gantry crane) hangs one end on your structure? What affects the quote once site work is counted? And which documents prove the crane meets the rules of my market?
This guide answers them in that order: how a semi gantry crane compares with full gantry and overhead cranes, four checks to run on your site, how to match the BMH or BMG to your load, what affects the quote and lead time, and which certificates to ask for before you buy.
Quick comparison
| Semi gantry crane | Full gantry crane | Overhead bridge crane | |
|---|---|---|---|
| Support | One ground leg + one runway on the building | Two ground legs | Runways on both sides of the building |
| Needs building structure | One side | Нет | Both sides |
| Ground rails | One | Two | Никто |
| Floor left free | One side | Little along the leg lines | Most of the floor |
| Best fit | Permanent building with one strong wall or column line | Open yards, weak or temporary buildings | Bays with strong structure on both sides |
Not sure which column your site falls in? Get a tailored quote from our engineers and we will check your layout.
Получить бесплатное предложениеSemi Gantry Crane vs Full Gantry vs Overhead Crane
When a Semi Gantry Crane Fits
It borrows support from a wall or column row, so you only build a ground rail on the other side. That keeps a loading lane, aisle or conveyor side free of legs. It also helps in existing workshops where an overhead crane would need both sides strengthened. Typical users are steel fabrication bays, heavy machinery assembly and automotive component plants. The trade-off is dependency: the crane is only as good as the structure it rides on.
When a Full Gantry Crane Wins
A full gantry crane stands on its own legs and ground rails, so it suits open yards, temporary sheds and weak buildings. It costs more floor space and civil work, since two rails need foundations. It can also be moved more easily if the site changes. Our range of козловые краны covers this route.
When an Overhead Crane Is Better
If both walls or column lines can carry runway beams, an overhead crane leaves the entire floor free of rails and legs. The catch is structure on both sides, which is often the expensive part in retrofit projects. Compare it with a semi gantry crane using the checks below, or review our мостовые краны.
Four Site Checks Before You Specify a Semi Gantry Crane
Building Runway Capacity
Have a structural engineer confirm the high-side wall or column line can carry the crane's vertical and horizontal loads. Without that check, a semi gantry crane is not safe to specify. Vertical load includes the crane's own weight plus the rated load, and horizontal load comes from travelling, braking and off-centre lifts. The engineer needs the crane's maximum wheel load, wheel spacing and travel speed, so ask your supplier for these at enquiry, not after the order. If the result is marginal, you can reinforce the structure, choose a lower capacity, or move to a full gantry crane. In an existing building, also confirm that column positions and heights suit the runway you need.
Floor Side and Ground Rail
The ground side needs a level, stable rail foundation, and the hook must be able to reach where you actually set loads down. One ground rail is simpler than two, but poor soil or an uneven slab causes rail wear and travel problems. Check three things: the foundation under the rail line, the clear distance between the leg line and the nearest wall or machine, and how close the hook can get to the leg side. Also mark forklift and pedestrian routes, since keeping one side clear is usually the reason to choose this crane in the first place.
Span, Height and Capacity
Span, lifting height and capacity should come from measured rail positions and lift points, not from the size of the room. Span is measured between rail centrelines, and lifting height from floor to hook at its highest working position. Dafang's BMH covers spans of 10–20 m and the BMG 6–24 m. For the BMG, span and hook height are fixed at manufacture, so confirm building geometry, process flow and any future capacity needs during quotation.
Duty Class and Outdoor Use
Duty class should follow your lift pattern, and a semi gantry crane can work outdoors only if its structure and protection are designed for it. Under ISO 4301 and FEM classification, duty depends on the load spectrum and the total number of lifting cycles. Two cranes with the same rating can wear very differently: one lifting near capacity every few minutes needs a higher class than one used for occasional maintenance. In Dafang's published data, the BMH parameter table lists A3 duty, while the BMG covers A5, A6 and A7. For outdoor or semi-open sites, check wind load, corrosion protection, rail anchoring and electrical protection; the BMG uses IP54 electrical enclosures as standard (IP65 on request).
BMH or BMG: Which Semi Gantry Crane Fits Your Load
| BMH | BMG | |
|---|---|---|
| Girder | Single girder | Double girder, box section |
| Вместимость | 2–10 t | 5–320 t |
| Спам | 10–20 m | 6–24 м |
| Подъемный механизм | Wire rope electric hoist | Electric trolley |
| Класс службы | A3 (10 t parameter table) | A5, A6, A7 |
| Certificates | CE / ISO | CE / ISO |
BMH Single-Girder Crane (2–10 t)
Сайт BMH semi gantry crane uses a single girder and a wire rope электрическая таль, which keeps weight and installation effort down. It is aimed at light industrial manufacturing, warehousing, machinery workshops and automotive repair. Its published specification lists frequency-controlled travel and safety devices including overload protection, travel limits and an emergency stop, with manual or remote operation. Where loads stay light and spans moderate, it is usually the simpler route.
BMG Double-Girder Crane (5–320 t)
Сайт BMG semi gantry crane uses a box-section double girder in Q355B steel, with deflection held within L/1000 at rated load. The structure is verified by finite element analysis, and the crane runs at 1–10 m/min lifting speed and 35–40 m/min bridge travel, with pendant, wireless or cab control. Three standard configurations cover most projects:
| Конфигурация | Спам | Вместимость | Класс службы |
|---|---|---|---|
| Стандарт | 6–16 м | 5–50 т | А5 |
| Medium-duty | 12–20 м | 20–160 т | A5/A6 |
| Heavy-duty | 16–24 м | 80–320 т | A6/A7 |
Typical users include steel service centres, heavy machinery plants, automotive component lines, precast yards and shipbuilding workshops. If you are weighing the BMG against a full двухбалочный козловой кран, send your span and duty pattern for a side-by-side check.
Why Span Changes Wheel Load
Span changes wheel load, so the same crane type can pass or fail your building check depending on how wide the bay is. For the 10 t BMH, the parameter table lists a maximum wheel loading of 78 kN at a 10 m span, 85 kN at 12 m, 94 kN at 16 m and 103 kN at 20 m. Those are the kind of figures your structural engineer needs. Ask for the equivalent data for your exact span and capacity before you finalise the building check.
Not sure whether your building qualifies? Send your bay layout, span, capacity and lifting height, and a Dafang engineer will recommend BMH or BMG for your site. Get a tailored quote from our engineers or message us on WhatsApp.
What Affects a Semi Gantry Crane Quote and Lead Time
Five Factors That Move the Price
Capacity, span, duty class, control system and site conditions move the price of a semi gantry crane more than any brand claim. Give your supplier these details up front and quotes become directly comparable:
- Capacity and girder type: single girder or double girder, and the real maximum load.
- Span and lifting height: wider spans and higher hooks add steel and drive wheel loads.
- Класс службы: a higher class means stronger drivetrain components.
- Control and electrical: pendant, wireless remote or cab, frequency control, and your local voltage and frequency.
- Environment and site work: indoor or outdoor, wind and corrosion needs, plus building reinforcement, rail foundation, freight and installation.
Dafang engineers review your building geometry, process flow and future capacity needs during quotation.
BMG Lead Time
Dafang's published BMG lead time is 30–45 days after drawing approval for 6–20 m spans at A5/A6 duty with pendant or remote control. Non-standard builds, such as unusual spans, A7 duty, explosion-proof specifications or outdoor duty with wind load certification, may take 50–60 days. Because the clock starts at drawing approval, finish the building check first. BMH delivery time is confirmed per order. For the BMG, site installation support is available.
Certificates to Request Before You Buy a Semi Gantry Crane
Which Certificates Your Market Needs
Requirements vary by country, so start from where the crane will be installed. Common references include:
- CE marking under the Machinery Directive 2006/42/EC for the EU and EEA
- EAC for Eurasian Economic Union markets
- ISO 9001 for the manufacturer's quality system
- ISO 4301 and FEM as the classification and design basis
- OSHA rules in the United States, where compliance generally rests with the site owner and installer rather than a manufacturer's certificate
Check current local requirements with your authority or installer.
ЧЗВ
Q1：How do I know if my building can support a semi gantry crane?
Have a structural engineer check the runway wall or columns against the crane's maximum wheel loads. Request the wheel load, wheel spacing and travel speed from your supplier at enquiry so the engineer works from real figures. If the building is marginal, reinforce it, choose a smaller capacity, or consider a full gantry crane.
Q2：What affects the price of a semi gantry crane?
Capacity, span, lifting height, duty class and control system move the price most, plus site costs. Girder type, voltage, indoor or outdoor duty, wind and corrosion needs also change the specification. Reinforcement, rail foundation, freight and installation sit outside the crane itself. Send your drawings and lift pattern so we can quote against real dimensions.
Q3：Can a semi gantry crane work outdoors?
Yes, if the building side, ground rail and electrical protection are designed for outdoor conditions. Specify wind load, corrosion protection and rail anchoring. The BMG uses IP54 electrical enclosures as standard, with IP65 available on request, and wind load calculations are available for exposed sites. The high side still needs a supporting structure.
Q4：How long does delivery take?
Dafang's standard BMG lead time is 30–45 days after drawing approval, and 50–60 days for non-standard configurations. BMH delivery time is confirmed per order. Finish your building assessment first, since the schedule starts once drawings are approved and dimensions are fixed at manufacture.
