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 rails and runway alignment—all explained in clear, real-world language.
Overhead Crane, Defined
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 result is smooth X-Y-Z motion: long-travel along the runway.
They’re the backbone of heavy shops and assembly lines, from beam handling to turbine assembly.
Why they matter:
Controlled moves for large, expensive equipment.
Huge efficiency gains.
Repeatable, precise positioning that reduces damage.
High throughput with fewer ground obstructions.
What This Install Includes
Runways & rails: continuous beams and rail caps.
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: end stops, buffers, travel limits.
Based on design loads and bay geometry, you may be dealing with modest shop lifts or major industrial picks. 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: Approve general arrangement (GA), electrical schematics, and loads to the structure.
Permits/JSAs: Permit-to-work, hot work, working at height, rigging plans.
Runway verification: Check baseplates, grout pads, and anchor torque.
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.
Millimeters at the runway become centimeters at full span. Spend time here.
Rails & Runways
Runway alignment is the foundation. Targets and checks:
Straightness & elevation: Laser or total station to set rail height.
Gauge (span) & squareness: Check centerlines at intervals; confirm end squareness and expansion joints.
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: Choose spreader bars to keep slings clear of electricals. Dedicated signaler on radio.
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 prefabricated structures and pin/bolt per GA.
Measure diagonal distances to confirm squareness.
Before anyone celebrates, bump-test long-travel motors with temporary power (under permit): ensure correct rotation and brake release. Lock out after test.
The Heart of the Lift
Trolley installation: Mount wheels, align wheel flanges, set side-clearances.
Hoist reeving: Lubricate wire rope; verify dead-end terminations.
Limits & load devices: Check overload/SLI and emergency stop.
Cross-travel adjustment: Align trolley rails on a double-girder.
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. Don’t mask issues with higher VFD ramps.
Electrics & Controls
Power supply: Drop leads tagged and strain-relieved.
Drive setup: Enable S-curve profiles for precise positioning.
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.
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.
QA/QC is not paperwork—it’s your warranty in a binder.
Ready for Work
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: Operator basics, daily pre-use checks, rigging do’s & don’ts.
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.
Controls that Matter
Rigging discipline: rated slings & shackles, correct angles, spreader bars for load geometry.
Lockout/Tagout: test before touch every time.
Fall protection & edges: scissor lifts and manlifts inspected.
Runway integrity: regular runway inspection plan.
Duty class selection: match crane class to cycles and loads.
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: antenna placement for radio; inspect festoon collectors.
Wheel wear & rail pitting: add rail sweeps and check clip torque.
Little noises are messages—listen early.
Quick Answers
Overhead vs. gantry? Bridge cranes ride fixed runways; gantries walk on the floor.
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.
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 see how small alignment wins become big reliability wins.
Need a field bundle with JSA templates, rigging calculators, and commissioning sheets?
Download your pro bundle 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