In large construction and fabrication spaces, overhead/bridge cranes do the heavy lifting—literally. This long-form walkthrough follows the journey from bare runways to a commissioned crane ready for service. You’ll see rails and runway alignment—all explained in clear, real-world language.
What an Overhead/Bridge Crane Is
An overhead crane rides on parallel runways anchored to a building frame, with a trolley that travels left-right along the bridge and a hoist that lifts the load. The system delivers three axes of motion: cross-travel along the bridge.
They’re the backbone of heavy shops and assembly lines, from beam handling to turbine assembly.
Why they matter:
Safe handling of very heavy, unwieldy loads.
Huge efficiency gains.
Lower risk during rigging, lifting, and transport inside facilities.
High throughput with fewer ground obstructions.
Scope at a Glance
Runways & rails: continuous beams and rail caps.
End trucks: wheel assemblies that ride the rail.
Bridge girder(s): cambered and pre-wired.
Trolley & hoist: reeving, hook block, upper limit switches.
Electrics & controls: power supply, festoon or conductor bars.
Stops, bumpers & safety: end stops, buffers, travel limits.
Based on design loads and bay geometry, the crane might be a single-girder 10-ton unit or a massive double-girder 100-ton system. The installation flow stays similar, with heavier rigs demanding extra controls and sign-offs.
Make-Ready & Surveys
Good installs start on paper. Key steps:
Drawings & submittals: Freeze the GA and verify reactions with the structural team.
Permits/JSAs: Permit-to-work, hot work, working at height, rigging plans.
Runway verification: Survey columns and runway beams for straightness, elevation, and span.
Power readiness: Confirm conductor bars or festoon supports, cable trays, and isolation points.
Staging & laydown: Lay out slings, shackles, spreader bars, and chokers per rigging plan.
People & roles: Brief everyone on radio calls and stop-work authority.
Tiny survey errors balloon into hours of rework. Measure twice, lift once.
Getting the Path Right
If rails are off, nothing else will run true. Targets and checks:
Straightness & elevation: Laser or total station to set rail height.
Gauge (span) & squareness: Use feeler gauges on splice bars, torque rail clips.
End stops & buffers: Install and torque per spec.
Conductor system: Mount conductor bars or festoon track parallel to the rail.
Log final numbers on the ITP sheet. Correct now or pay later in wheel wear and motor overloads.
Putting the Span in the Air
Rigging plan: Softeners protect painted flanges. Dedicated signaler on radio.
Sequence:
Install end trucks at staging height to simplify bridge pick.
For double-girder cranes, lift both girders with a matched raise.
Use drift pins to align flange holes; torque to spec.
Verify camber and bridge square.
Before anyone celebrates, bump-test long-travel motors with temporary power (under permit): ensure correct rotation and brake release. Re-apply LOTO once checks pass.
The Heart of the Lift
Trolley installation: Hoist/trolley arrives pre-assembled or as modules.
Hoist reeving: Lubricate wire rope; verify dead-end terminations.
Limits & load devices: Set upper/lower limit switches.
Cross-travel adjustment: Verify end stops and bumpers.
Pendant/remote: Install pendant festoon or pair radio receiver; function-test deadman and two-step speed controls.
Grinding noises mean something’s off—stop and inspect. Fix the mechanics first.
Drive Tuning & Interlocks
Power supply: Conductor bars with collectors or a festoon system.
Drive setup: Program VFDs for soft starts, decel ramps, and brake timing.
Interlocks & safety: E-stops, limit switches, anti-collision (if multiple cranes), horn, beacon.
Cable management: Keep loops short, add drip loops where needed.
Commissioning crews love clean labeling and clear folders. If it isn’t documented, it didn’t happen—put it in the databook.
Trust but Verify
Inspection Test Plan (ITP): Hold/witness points for rail alignment, torque, electrical polarity, limit settings.
Torque logs: Record wrench serials and values.
Level & gauge reports: Attach survey prints.
Motor rotation & phasing: Document bump tests.
Functional tests: bloomberg building Anti-collisions and zone interlocks.
A tidy databook speeds client acceptance.
Proving the System
Static load test: Apply test weights at the hook (usually 100–125% of rated capacity per spec).
Dynamic load test: Travel long-run, cross-travel, and hoist at rated speed with test load.
Operational checks: Emergency stop shuts down all motions.
Training & handover: Operator basics, daily pre-use checks, rigging do’s & don’ts.
Only after these pass do you hand over the keys.
Applications & Use Cases
Construction & steel erection: placing beams, trusses, and precast.
Oil & gas & power: generator and turbine assembly.
Steel mills & foundries: hot metal handling (with the right duty class).
Warehousing & logistics: high throughput lanes.
Floor stays clear, production keeps flowing, and precision goes up.
Controls that Matter
Rigging discipline: dedicated signaler and stop-work authority.
Lockout/Tagout: test before touch every time.
Fall protection & edges: approved anchor points, guardrails on platforms, toe boards.
Runway integrity: no cracked welds, correct bolt grades, proper grout.
Duty class selection: overspec when uncertainty exists.
A perfect lift is the one nobody notices because nothing went wrong.
Keep It Rolling
Crab angle/drift: re-check runway gauge and wheel alignment.
Hot gearboxes: misalignment or over-tight brakes.
Rope drum spooling: check fleet angle and sheave alignment.
Pendant lag or dropout: shield noisy VFD cables.
Wheel wear & rail pitting: add rail sweeps and check clip torque.
A 10-minute weekly check saves days of downtime later.
Quick Answers
Overhead vs. gantry? Bridge cranes ride fixed runways; gantries walk on the floor.
Single vs. double girder? Singles are lighter and cheaper; doubles carry heavier loads and give more hook height.
How long does install take? Anything from a couple weeks to a few months.
What’s the duty class? FEM/ISO or CMAA classes define cycles and service—don’t guess; size it right.
Who Gets the Most Value
If you’re a civil or mechanical engineer, construction manager, shop supervisor, or just a mega-project fan, this deep dive makes the whole process tangible. You’ll see how small alignment wins become big reliability wins.
Want ready-to-use checklists for runway surveys, torque logs, and load-test plans?
Get the toolkit now so your next crane goes in cleaner, faster, and right the first time. Save it to your site tablet for quick reference.
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