In large construction and fabrication spaces, overhead/bridge cranes do the heavy lifting—literally. This practical guide shows how a full overhead crane system comes to life inside a structural building. You’ll see final load testing and handover—all explained in clear, real-world language.
Bridge Crane Basics
At heart, a bridge crane is a bridge beam that spans between two runway beams, carrying a trolley-mounted hoist for precise, vertical picks. The result is smooth X-Y-Z motion: long-travel along the runway.
You’ll find them in fabrication bays, steel plants, power stations, oil & gas shops, precast yards, and logistics hubs.
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.
What This Install Includes
Runways & rails: runway girders with crane rail and clips.
End trucks: motorized gearboxes for long-travel.
Bridge girder(s): single- or double-girder configuration.
Trolley & hoist: reeving, hook block, upper limit switches.
Electrics & controls: VFDs, radio remote, pendant.
Stops, bumpers & safety: overload protection, e-stops.
Depending on capacity and span, the crane might be a single-girder 10-ton unit or a massive double-girder 100-ton system. The choreography is similar, but the scale, lift plans, and checks grow with the tonnage.
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.
Millimeters at the runway become centimeters at full span. Measure twice, lift once.
Rails & Runways
Runway alignment is the foundation. 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: Keep dropper spacing uniform; ensure collector shoe reach.
Record as-built readings. Correct now or pay later in wheel wear and motor overloads.
Lifting the Bridge
Rigging plan: Choose spreader bars to keep slings clear of electricals. Taglines for swing control.
Sequence:
Install end trucks at staging height to simplify bridge pick.
Rig the bridge girder(s) and make the main lift.
Use drift pins to align flange holes; torque to spec.
Verify camber and bridge square.
Prior to trolley install, bump-test long-travel motors with temporary power (under permit): confirm limit switch wiring. Lock out after test.
Hoist & Trolley
Trolley installation: Mount wheels, align wheel flanges, set side-clearances.
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.
A smooth trolley with a quiet hoist is a sign of good alignment. Fix the mechanics first.
Electrics & Controls
Power supply: Conductor bars with collectors or a festoon system.
Drive setup: Enable S-curve profiles for precise positioning.
Interlocks & safety: Zone limits near doors or mezzanines.
Cable management: Secure junction boxes; label everything for maintenance.
Commissioning crews love clean labeling and clear folders. Photos of terminations help later troubleshooting.
Trust but Verify
Inspection Test Plan (ITP): Third-party witness for critical steps.
Torque logs: Re-check after 24 hours if required.
Level & gauge reports: Note any corrective shims.
Motor rotation & phasing: Document bump tests.
Functional tests: Anti-collisions and zone interlocks.
QA/QC is not paperwork—it’s your warranty in a binder.
Load Testing & Commissioning
Static load test: Hold at mid-span and near end stops; monitor deflection and brake performance.
Dynamic load test: Check sway, braking distances, and VFD fault logs.
Operational checks: Limit switches trigger reliably; overload trips; horn/beacon function.
Training & handover: Maintenance intervals for rope, brakes, and gearboxes.
Only after these pass do you hand over the keys.
Everyday Heavy Lifting
Construction & steel erection: handling long members safely.
Oil & gas & power: generator and turbine assembly.
Steel mills & foundries: large part transfer.
Warehousing & logistics: bulk material moves with minimal floor traffic.
Floor stays clear, production keeps flowing, and precision goes up.
Do It Safe or Don’t Do It
Rigging discipline: dedicated signaler and stop-work authority.
Lockout/Tagout: test before touch every time.
Fall protection & edges: scissor lifts and manlifts inspected.
Runway integrity: no cracked welds, correct bolt grades, proper grout.
Duty class selection: overspec when uncertainty exists.
Safety isn’t a stage—it's the whole show.
If It Doesn’t Run Smooth
Crab angle/drift: re-check runway gauge and wheel alignment.
Hot gearboxes: adjust brake air gap and reduce VFD decel.
Rope drum spooling: dress rope and reset lower limit.
Pendant lag or dropout: antenna placement for radio; inspect festoon collectors.
Wheel wear & rail pitting: add rail sweeps and check clip torque.
A 10-minute weekly check saves days of downtime later.
FAQ Snippets
Overhead vs. gantry? Choose per site constraints.
Single vs. double girder? Span and duty class usually decide.
How long does install take? Scope, bay readiness, and tonnage rule the schedule.
What’s the duty class? FEM/ISO or CMAA classes define cycles absolute construction and service—don’t guess; size it right.
Why Watch/Read This
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.
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