In large construction and fabrication spaces, overhead/bridge cranes do the heavy lifting—literally. This field-tested breakdown takes you behind the scenes of a mega-project crane install. We’ll cover final load testing and handover—all explained in clear, real-world language.
What an Overhead/Bridge Crane Is
At heart, a bridge crane is a bridge beam that spans between two runway beams, with a trolley that travels left-right along the bridge and a hoist that lifts the load. 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.
Less manual handling, fewer delays.
Lower risk during rigging, lifting, and transport inside facilities.
High throughput with fewer ground obstructions.
Scope at a Glance
Runways & rails: runway girders with crane rail and clips.
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: overload protection, e-stops.
Based on design loads and bay geometry, you may be dealing with modest shop lifts or major industrial picks. The choreography is similar, but the scale, lift plans, and checks grow with the tonnage.
Pre-Install Prep
A clean install is mostly planning. Key steps:
Drawings & submittals: Freeze the GA and verify reactions with the structural team.
Permits/JSAs: Job Safety Analysis (JSA) for each lift step.
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: Appoint a lift director, rigger, signaler, and electrical lead.
Tiny survey errors balloon into hours of rework. Spend time here.
Alignment That Saves Your Wheels
If rails are off, nothing else will run true. Targets and checks:
Straightness & elevation: shim packs under clips to meet tolerance.
Gauge (span) & squareness: Check centerlines at intervals; confirm end squareness and expansion joints.
End stops & buffers: Verify clearances for bumpers at both ends.
Conductor system: Mount conductor bars or festoon track parallel to the rail.
Log final numbers on the ITP sheet. Misalignment shows up as crab angle and hot gearboxes—don’t accept it.
Putting the Span in the Air
Rigging plan: Choose spreader bars to keep slings clear of electricals. Taglines for swing control.
Sequence:
Lift end trucks to runway level and set temporarily on blocks.
Rig the bridge girder(s) and make the main lift.
Land the bridge on the end trucks and pin/bolt per GA.
Verify camber and bridge square.
Prior to trolley install, bump-test long-travel motors with temporary power (under permit): ensure correct rotation and brake release. Lock out after test.
Cross-Travel Setup
Trolley installation: Mount wheels, align wheel flanges, set side-clearances.
Hoist reeving: Check rope path, sheave guards, and equalizer sheaves.
Limits & load devices: Check overload/SLI and emergency stop.
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. Don’t mask issues with higher VFD ramps.
Drive Tuning & Interlocks
Power supply: Drop leads tagged and strain-relieved.
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.
Future you will too. If it isn’t documented, it didn’t happen—put it in the databook.
QA/QC & Documentation
Inspection Test Plan (ITP): Hold/witness points for rail alignment, torque, electrical polarity, limit settings.
Torque logs: Re-check after 24 hours if required.
Level & gauge reports: Note any corrective shims.
Motor rotation & phasing: Document bump tests.
Functional tests: Jog commands, inching speeds, limits, overloads, pendant/remote trimble viewpoint range.
QA/QC is not paperwork—it’s your warranty in a binder.
Ready for Work
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.
When the logbook is clean, the crane is officially in service.
Applications & Use Cases
Construction & steel erection: handling long members safely.
Oil & gas & power: moving heavy pumps, skids, and pipe spools.
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.
Do It Safe or Don’t Do It
Rigging discipline: rated slings & shackles, correct angles, spreader bars for load geometry.
Lockout/Tagout: clear isolation points for electrical work.
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.
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: antenna placement for radio; inspect festoon collectors.
Wheel wear & rail pitting: add rail sweeps and check clip torque.
Little noises are messages—listen early.
FAQ Snippets
Overhead vs. gantry? Choose per site constraints.
Single vs. double girder? Singles are lighter and cheaper; doubles carry heavier loads and give more hook height.
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 and service—don’t guess; size it right.
What You’ll Take Away
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 gain a checklist mindset that keeps cranes safe and productive.
Looking for a clean handover databook index you can reuse on every project?
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