Overhead cranes—often called bridge cranes—are the quiet workhorses that keep heavy industry moving. This long-form walkthrough follows the journey from bare runways to a commissioned crane ready for service. You’ll see rails and runway alignment—with the same checklists pro installers use.
Overhead Crane, Defined
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: cross-travel along the bridge.
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): single- or double-girder configuration.
Trolley & hoist: cross-travel carriage with lifting unit.
Electrics & controls: power supply, festoon or conductor bars.
Stops, bumpers & safety: overload protection, e-stops.
Depending on capacity and span, you may be dealing with modest shop lifts or major industrial picks. The choreography is similar, with heavier rigs demanding extra controls and sign-offs.
Before the First Bolt
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: Check baseplates, grout pads, and anchor torque.
Power readiness: Lockout/tagout plan for energization.
Staging & laydown: Mark crane components with ID tags.
People & roles: Appoint a lift director, rigger, signaler, and electrical lead.
Millimeters at the runway become centimeters at full span. Measure twice, lift once.
Alignment That Saves Your Wheels
Runway alignment is the foundation. 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 building services rail.
Log final numbers on the ITP sheet. Misalignment shows up as crab angle and hot gearboxes—don’t accept it.
Lifting the Bridge
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.
Measure diagonal distances to confirm squareness.
Prior to trolley install, bump-test long-travel motors with temporary power (under permit): confirm limit switch wiring. 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.
A smooth trolley with a quiet hoist is a sign of good alignment. Fix the mechanics first.
Power with Discipline
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.
ITP, Checklists, and Sign-Off
Inspection Test Plan (ITP): Third-party witness for critical steps.
Torque logs: Record wrench serials and values.
Level & gauge reports: Note any corrective shims.
Motor rotation & phasing: Confirm brake lift timing.
Functional tests: Jog commands, inching speeds, limits, overloads, pendant/remote range.
A tidy databook speeds client acceptance.
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: 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.
Where These Cranes Shine
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.
Once teams learn the motions, cycle times drop and safety improves.
Safety & Engineering Considerations
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.
A perfect lift is the one nobody notices because nothing went wrong.
Keep It Rolling
Crab angle/drift: verify end-truck wheel diameters and gearbox mounts.
Hot gearboxes: misalignment or over-tight brakes.
Rope drum spooling: dress rope and reset lower limit.
Pendant lag or dropout: shield noisy VFD cables.
Wheel wear & rail pitting: lubrication and alignment issues.
Little noises are messages—listen early.
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 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 gain a checklist mindset that keeps cranes safe and productive.
Looking for a clean handover databook index you can reuse on every project?
Grab the installer pack so your next crane goes in cleaner, faster, and right the first time. Save it to your site tablet for quick reference.
...
Read more arabic articles...
read more about this products