Your crane hangs from the roof, so the support steel check comes first. Eight on-site stages, suspension point loads from 1 to 5 tons, ASME B30.11 rules for hanger rods and sway bracing, 2026 cost ranges, and the load test values you have to hit before production starts.
A suspension crane installation runs 6 to 13 working days on site for a typical 1 to 5 ton system, and the thing that decides the schedule is usually not the crane. It is the support steel. An underslung crane hangs from hanger rods fixed to your roof structure, so every suspension point has to be checked before anything is lifted. Budget USD 2,000 to 10,000 for installation labour, 30% to 60% on top of the crane price for the complete system, and hold the runway span to plus or minus 5 mm before the bridge goes on.
This guide covers the eight on-site stages, why the support steel check comes first, the ASME B30.11 rules for hanger rods and sway bracing, ISO 12488-1 track tolerances, 2026 cost ranges by capacity, and what the load test has to prove before you sign anything. Written for plant engineers and maintenance managers who own the installation contract.
Installation, assembly and commissioning get used as if they mean the same thing. They don't, and on a suspension crane the gap between them is bigger than on a top-running crane. Installation is everything physical on site. Assembly is bolting the runway track together and dropping the bridge onto it. Commissioning is the aligning, testing and calibrating that turns a hanging structure into a certified lifting appliance.
A supplier quoting "installation and commissioning" may only mean the last part. Read the scope line carefully. And note that two of the eight stages below normally belong to your steel contractor or your structural engineer, not to the crane supplier.
| Stage | Typical duration | Usually done by |
|---|---|---|
| 1. Roof structure survey and support steel check | 1-3 days | Owner's structural engineer plus crane engineer |
| 2. Suspension point layout and hanger design approval | 3-10 days (office work) | Crane supplier engineering |
| 3. Track offload, floor layout and pre-assembly | 1 day | Installation crew |
| 4. Hanger brackets or beam clamps fixed to the structure | 1-2 days | Installation crew |
| 5. Hanger rods and sway bracing installed | 1-2 days | Installation crew plus steel contractor |
| 6. Runway track hoisted, spliced and aligned | 1-3 days | Installation crew |
| 7. Bridge placed, end trucks engaged, electrical connected | 1-2 days | Installation crew with electrician |
| 8. Final alignment, load test and handover | 1-2 days | Commissioning engineer, third party if required |
Add the eight up and you get 6 to 13 working days on site for a mid-size unit. Stage 2 happens in the factory office while the crane is being fabricated, so it costs you nothing in site time. Stages 4 and 5 are the ones that stall. If your steel contractor is not booked, the crew stands around.
The determinant is not tonnage. It is whether the support steel already exists at the right centres and at the right height. A plant that put a runway beam in during a previous fit-out will see the crane go up in under a week. A retrofit into a building where the roof was designed for roof loads only will take two to three times as long, mostly waiting on steel work and structural sign-off.
| Capacity | Typical span | Site days, support steel ready | Site days, steel to be added |
|---|---|---|---|
| 0.5-1 t | 5-10 m | 3-5 | 6-10 |
| 1-2 t | 8-14 m | 4-7 | 8-13 |
| 2-3.2 t | 10-16 m | 5-9 | 10-16 |
| 3.2-5 t | 12-18 m | 6-11 | 12-20 |
Then add the time you never put in the plan. Total project time from enquiry to handover for a custom underslung crane runs 6 to 12 weeks, because design approval, fabrication, shop assembly and pre-delivery inspection all happen before a truck arrives. The site work is the short part.
One more thing worth knowing before you pick dates. Multi-span or monorail systems take longer than the table above suggests. Every additional track run needs its own hanger points and its own alignment pass, and the interlocking sections between runs have to be set so carriers transfer cleanly. If your layout has three tracks and two transfer points, plan for the upper end of the range and then some.
This is the stage that gets skipped and then costs the most money. An underslung crane puts its entire load, crane plus payload, into the roof or into purpose-built runway beams. The floor carries nothing. If those beams were sized for roof sheeting and snow, they were never meant to see a 4 ton point load swinging past them twenty times a shift.
What your structural engineer needs from the crane supplier is the suspension point load, not the rated capacity. Those are different numbers. A 3.2 ton crane can put close to 5 tons into a single hanger point once the wheel load, the dynamic factor and the crane's own weight are in the calculation.
| Rated capacity | Approx. crane dead weight | Max wheel load | Design load per suspension point |
|---|---|---|---|
| 1 t | ~950 kg | ~1.4 t | ~2.0 t |
| 2 t | ~1,450 kg | ~2.2 t | ~3.2 t |
| 3.2 t | ~2,100 kg | ~3.2 t | ~4.6 t |
| 5 t | ~3,200 kg | ~4.8 t | ~7.0 t |
The point load above assumes the worst realistic position: two end truck wheels sitting either side of one hanger, with a 1.3 dynamic factor. Actual figures depend on your wheelbase and hanger spacing, and the supplier should give you the real wheel load drawing. Use these as a sizing check, not a substitute for the drawing.
Three things the survey has to answer. First, can the existing beams take the point load, including the local flange condition where the clamp or bracket sits. Second, is there enough depth above the track run for the hanger rod and its locking hardware. Third, does anything else already occupy that zone, such as cable trays, ducting or sprinkler pipe. Moving services is cheap before the track is up and miserable afterwards.
On older buildings, watch for beams that have been drilled or notched by previous trades, and for connections that were never sized for fatigue. A suspension point loads the same detail thousands of times a year, and cyclic loading finds weaknesses that a static check misses.
Set the track out from the crane's span, not from the building's centreline. Buildings are rarely square, and if you pull the runway spacing from a column line the bridge will fight the track for its whole life. Mark the hanger positions on the floor first, project them up, and confirm the spacing at both ends before drilling anything.
Then hold the alignment values. ISO 12488-1:2012, identical to GB/T 10183.1-2018, is the reference the crane is built to, and it is also what your installer should be measuring against.
| Check | Grade 2 (standard cranes) | Grade 1 (high speed or precision) |
|---|---|---|
| Span tolerance, S up to 16 m | ±5 mm | ±3 mm |
| Span tolerance, S over 16 m | ±[5 + 0.25 × (S − 16)] mm, max ±15 mm | max ±10 mm |
| Rail straightness, horizontal plane, full runway | ±10 mm | Per project specification |
| Height difference between opposite tracks | ±1.0 × S mm, max ±10 mm | ±0.5 × S mm, max ±5 mm |
| End stop and buffer parallelism | ±1.0 × S mm, max ±10 mm | Per project specification |
| Hanger rod plumbness | Within manufacturer's tolerance | Same |
For an underslung crane the height difference between opposite tracks is the value people get wrong, because each track hangs independently. With a 12 m span the cap works out at 12 mm on paper, but the absolute limit is 10 mm and most installations should be inside 6 mm. If one track is hung 12 mm lower than the other, the bridge sits on a slope, one end truck carries more load than the other, and the wheels wear unevenly.
Track splices matter just as much. Align the surface and the sides of the load-carrying flange, because that flange is the running surface. ASME B30.11 11-1.3.1(c) puts it plainly: splices have to ensure proper alignment of the flange surface and sides. On site, keep the splice within 1,220 mm of a hanger or a splice hanger. Further away than that and the track sags at the joint, the trolley bumps its way across, and you get fatigue cracking in the splice plates within a couple of years.
The runway normally extends past the last support at each end, and the amount depends on the track type. Plain track typically runs 115 to 305 mm beyond the last support. Trussed track can go up to 1,220 mm. Either way, the unsupported cantilever at the end of a runway should not exceed 460 mm. Festoon storage is allowed to extend further because it carries no travelling load.
Sway bracing is the single most common scope gap on suspension crane projects. It is needed on every system that uses drop rod hangers, in both the lateral and the longitudinal direction, at all four corners of the layout and at intermediate points. It is also, on most projects, supplied by others. Read that again: furnished by others means it sits in nobody's contract until someone notices the track is swinging.
Bracing is not a nice-to-have. It stops the track moving laterally and longitudinally under travelling and braking loads, and it stops the hanger hardware working loose. Without it, the rod nuts back off, the track shifts, and the alignment values you just spent two days hitting go out the window.
| Item | Requirement | Reference |
|---|---|---|
| Hanger rod plumb | Installed plumb within the manufacturer's tolerance | ASME B30.11 11-1.3.2(b) |
| Multiple rods at one suspension point | Design for the unequal load the rods will share | ASME B30.11 11-1.3.2(c) |
| Lateral and longitudinal restraint | Means provided to restrain the track against damaging movement | ASME B30.11 11-1.3.2(d) |
| Nut retention | Hanger rod nuts restrained from backing off | ASME B30.11 11-1.3.2(e) |
| Sway bracing where drop rods are used | Required at all corners, both directions, plus intermediate bracing at hangers closest to track splices | Underslung system installation manuals |
| Minimum bracing pipe size | 25 mm (1 in) nominal bore, schedule 40, for hanger rods up to 1.8 m (6 ft) long | Underslung system installation manuals |
| Rods longer than 1.8 m | Treat as a special case and engineer the restraint | Underslung system installation manuals |
| Field welding of track supports | Welding procedure to AWS D1.1; load-sustaining members to AWS D14.1 | ASME B30.11 11-1.3.4 |
| Beam clamp capacity, typical | Flange width up to 203 mm and thickness up to 11 mm; larger or sloped beams need a different clamp | Underslung system installation manuals |
Bolted clamps or bolted brackets are the usual route on retrofit work, because you avoid welding to a structure nobody wants to weld to. Where welding is used, the procedure has to be qualified. ASME B30.11 separates the two cases: welding on load-sustaining members of the crane follows AWS D14.1, and field welding of track supports follows AWS D1.1.
Clearance catches people out as well. Leave a minimum of 75 mm between the top of the bridge and any overhead obstruction, and at least 50 mm between the bridge ends and anything on the sides. That 75 mm looks generous on a drawing and looks very tight once cable trays and light fittings are hanging in the same zone.
Installation labour for a suspension crane is cheaper than for a top-running crane of similar capacity, because the track goes up in short sections instead of a single fabricated runway, and there is often no need for a large mobile crane. What offsets that saving is the support steel survey, the hanger brackets and the bracing, none of which exist on a floor-supported runway.
| Cost item | 2026 range (USD) | Notes |
|---|---|---|
| Installation labour and commissioning | 2,000-10,000 | Rises with track length and number of suspension points |
| Electrical supply, wiring and control panel | 1,000-5,000 | Depends on distance to the nearest supply and whether a crane busbar is needed |
| Hanger brackets, rods and bracing steel | 1,500-8,000 | Often excluded from the crane quotation entirely |
| Structural survey and design sign-off | 500-3,500 | Higher where existing drawings are missing or the structure is old |
| Wireless remote control | 1,000-3,000 | Optional; pendant control is included as standard |
| Overload limiter and safety package | 500-2,500 | Usually required for CE marking on European deliveries |
| Span premium beyond 8-12 m | 2,000-5,000 | Applies to the crane equipment, not the installation |
Roll that up to a complete system and the 2026 numbers look like this.
| Capacity | Crane equipment (USD) | Complete installed system (USD) |
|---|---|---|
| 0.5-1 t | 3,000-6,000 | 5,500-11,000 |
| 1-2 t | 4,500-9,000 | 8,000-15,000 |
| 2-3.2 t | 6,500-13,000 | 11,000-21,000 |
| 3.2-5 t | 9,000-22,000 | 15,000-33,000 |
Budget 30% to 60% on top of the bare crane price for a complete suspension crane system. That uplift is higher than a single girder top-running crane, which sits nearer 20% to 30%, and the reason is simple: hanger steel, bracing and a structural survey have no equivalent on a floor-supported runway.
Above about 5 tons the economics turn. An underslung crane at 10 tons needs a very substantial support structure, and a top-running single girder crane on columns usually works out cheaper once the steel is in the comparison. Underslung wins when headroom is the constraint, not when tonnage is.
Commissioning is where the crane stops being a structure and starts being a machine. On a suspension crane the sequence is: re-measure span and track height difference, check every hanger rod is plumb and every nut is locked, confirm bracing is complete in both directions, then verify the electrical functions before a test load goes anywhere near it.
Joint functions first, one at a time. Hoist up and down. Trolley full travel in both directions. Bridge full travel in both directions. Limits and stops. Then run them together at slow speed and listen for anything that knocks or scrapes. A trolley that bumps at a splice is a splice alignment problem, and it is far easier to fix now than after the load test certificate is signed.
| Test | Test load | What it proves |
|---|---|---|
| Static, rated load | 100% of rated capacity | Brakes hold, structure carries the load |
| Static, overload | 100% to 125% of rated capacity | Structural integrity; mid-span deflection measured |
| Dynamic | 110% of rated capacity | Hoist, trolley and bridge travel under load |
| End stop impact | Full load at 50% of rated travel speed | Stops resist the impact and keep the crane on the track |
The overload figure is normally 125% unless the manufacturer or a qualified person specifies otherwise. ASME B30.11 requires a written record of the test load and the operations performed, and that requirement is not limited to new cranes. A crane that has been reinstalled, altered, repaired or modified goes back through the same test. Re-rated systems are covered by 11-2.2 as well, and the new rated load has to be marked on the crane.
One exemption worth knowing: replacing a wire rope or a load chain does not by itself trigger a load test, provided you run the hoist through an operational check afterwards. A full load test is not required for a consumable swap. Structural work is a different story.
Do not accept a verbal sign-off. Ask for the measurements in writing and photograph the ones that are hard to re-check later, particularly the hanger connections and the bracing.
| # | Item | Acceptance value |
|---|---|---|
| 1 | Span measured and recorded | ±5 mm for spans up to 16 m at Grade 2 |
| 2 | Height difference between opposite tracks recorded | Max 10 mm at Grade 2 |
| 3 | Every hanger rod plumb, every nut locked against backing off | Visual plus torque check |
| 4 | Sway bracing complete, both directions, all corners and intermediates | Matches the approved layout drawing |
| 5 | Track splices aligned and positioned | Flange surface and sides aligned; within 1,220 mm of a hanger |
| 6 | End stops fitted at every open track end | Including crossovers, spurs and transfer sections |
| 7 | Clearances verified | 75 mm above the bridge, 50 mm at the ends |
| 8 | Electrical functions, limits and overload tested | Voltage, phase, earth, all controls and both limits |
| 9 | Load test completed with written report | Test load and operations documented |
| 10 | Rated load marked; drawings, manuals and spare parts list handed over | Marking visible to the operator |
The support steel assumption, by a distance. Someone looks up at a solid-looking roof beam and concludes it will hold. It might, but nobody has done the arithmetic, and the failure mode is not dramatic collapse. It is a beam that deflects a few millimetres, a connection that cracks after a year, and a change order in the middle of commissioning.
Second is bracing that nobody bought. The crane quotation excludes it, the steel contractor was never told, and the installation crew bolts the track up without it. The crane works. Then it starts swinging on the rods during travel, the alignment drifts, and the fix costs more than doing it properly would have.
Third is the splice placed where it was convenient rather than close to a hanger. Track sections are heavy, the installers want them joined where they can reach, and 1,500 mm between a splice and the nearest hanger does not look like a problem on the day. It shows up later as a bump every time the trolley crosses and, eventually, as cracking in the splice plates.
Fourth is the span that was never re-measured after the track went in. The bridge is fabricated to the span on the approved drawing. If the as-built track spacing differs, the wheels do not sit properly on both tracks and the bridge has to be re-shimmed or, in bad cases, the end trucks modified. Measure the as-built spacing and send it to the manufacturer before shipping is released. It takes under an hour.
Fifth, and this one is quietly expensive: services in the way. Sprinkler mains, compressed air runs, cable trays and lighting all end up in the zone above a proposed track. Relocating them is a separate trade, a separate quote, and a separate wait.
If you want a second opinion on any of this, our engineers review suspension crane layouts and support steel requirements before the order is placed, and we supply the suspension point load drawings your structural engineer needs. You can see the suspension crane range for capacities and standard spans, or compare the trade-offs in our cost and TCO analysis and the standards comparison.
For a 1 to 5 ton underslung crane with the support steel already in place, expect 3 to 11 working days on site. Where the steel has to be added or reinforced, budget 6 to 20 days. The eight-stage breakdown runs from roof survey through to load test, and the two stages that most often delay the schedule are the hanger bracket fixing and the sway bracing, both of which depend on your steel contractor rather than the crane crew.
Sometimes, but less often than people hope. The deciding number is the suspension point load, not the crane's rated capacity. A 3.2 ton crane typically puts about 4.6 tons into a single hanger point once wheel load and dynamic factor are included, and general warehousing roof steel is normally designed for roof loads only. A structural engineer has to check the beam capacity and the local condition of the flange where the clamp sits. On retrofit projects, reinforcement frequently costs more than the crane.
Sway bracing is diagonal restraint that stops the runway track moving laterally and longitudinally. Every underslung system using drop rod hangers needs it, in both directions, at all four corners of the layout, plus intermediate bracing at the hangers nearest each track splice. It is required not just for stability but to stop the hanger hardware loosening under cyclic loading. On most projects bracing steel is excluded from the crane quotation, so make sure somebody has it in their scope.
Installation labour and commissioning runs USD 2,000 to 10,000 depending on track length and the number of suspension points. Electrical work adds USD 1,000 to 5,000, and hanger brackets, rods and bracing steel add USD 1,500 to 8,000, often as a separate contract. For the complete installed system, budget USD 5,500 to 11,000 at 0.5 to 1 ton and USD 15,000 to 33,000 at 3.2 to 5 tons. That works out at 30% to 60% above the bare crane price.
ASME B30.11 requires the crane to be tested at rated load and above, normally 100% to 125% for the static test and 110% for the dynamic test, with the mid-span deflection measured and the results written up. The written record of test load and operations performed is mandatory, and it applies to reinstalled, altered, repaired and modified cranes, not only new ones. Re-rated systems are covered by section 11-2.2 and the new rated load must be marked on the crane.
Yes, in most cases. Bolted beam clamps are the standard method for retrofit work. A typical clamp suits flange widths up to 203 mm and flange thickness up to 11 mm, and larger or sloped beams need a clamp made for that section. Where welding is used instead, ASME B30.11 requires the procedure to be qualified: AWS D14.1 for load-sustaining members of the crane, and AWS D1.1 for field welding of track supports.
Send us your building drawings, clear height and lifting requirement. Our engineering team will confirm the crane that fits, the suspension point loads your structural engineer needs, the hanger and bracing arrangement, the track tolerances your installer must hold, and a full installation and commissioning scope so nothing falls between contracts.
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