Overhead crane load test: no load, static load, dynamic load
Overhead Crane Load Testing
Overhead crane load testing is a critical requirement mandated under OSHA regulations to confirm that electric hoists and overhead crane systems are in safe working condition before they are placed into service. These tests are performed to verify proper assembly in line with engineering design parameters and to ensure operational safety for both personnel and facilities.
What is a Crane Load Test?
A crane load test involves intentionally subjecting the overhead crane to loads beyond its rated capacity in order to assess its integrity and performance. The system must demonstrate the ability to lift and maneuver these loads through standard operating motions. In compliance with OSHA requirements, cranes are typically tested with up to 125% of the rated capacity.
Daily checks are required for wire ropes, hoist chains, and hooks, while full-scale load tests should be conducted every 6–12 months or as specified by applicable standards.
OSHA 1910.179 – Overhead & Gantry Crane Requirements
According to OSHA guidelines, all newly installed or modified cranes must undergo performance tests prior to initial use. These inspections include verification of:- Hoisting and lowering functions
- Trolley and bridge travel
- Limit switches, locking mechanisms, and safety devices
- Correct functioning of hoist limit switches under increasing speeds with no load
The test load must not exceed 125% of the rated load, unless otherwise recommended by the crane manufacturer. Test documentation must remain on file and accessible to designated personnel.
Types of Crane Tests
1. Preparation Before Testing
- Shut off power supply and inspect drive mechanisms against design data
- Verify rope winding on drums and pulleys
- Remove obstacles from tracks and clear the surrounding environment
- Check brake circuits, switches, and wiring integrity
- Confirm motor drive wiring is correct and secure
2. No-Load Test
- Operate each mechanism without load
- Verify lifting and travel limits
- Conduct three consecutive operation cycles, monitoring cabling, conductors, and motion smoothness
3. Static Load Test
- Apply gradually increasing load up to rated capacity and traverse the full bridge span three times
- With 125% of rated load lifted 100 mm above the ground, maintain suspension for 10 minutes
- Inspect for structural deformation, measure girder deflection, and verify compliance with design tolerances (e.g., span/800 for deflection limits)
4. Dynamic Load Test
- Conduct with 110% of rated load
- Operate all motions (forward/reverse) for at least one hour under intermittent duty cycles
- Check responsiveness of limit switches, interlocks, motor temperature rise, vibration levels, and abnormal noises
Overhead Crane Load Testing Procedures
When conducting crane load tests, loads must never exceed 125% of rated lifting capacity. All test reports must be properly filed for review by authorized personnel.Pre-Test Checklist
- Review operational limitations in the operator’s manual
- Verify that rigging and lifting attachments are properly rated and labeled
- Confirm completion of prior corrective actions from inspection reports
- Ensure safe working load is clearly posted on the crane
- Confirm that runway structures and supports can accommodate test loads
- Follow manufacturer guidelines, including reeving arrangements
- Establish exclusion zones for personnel safety
- Ensure all personnel (operators, riggers, signalers) are briefed on procedures
- Inspect structural components, runway alignment, and power systems prior to test
- Position trolley/hoist at specified test points
- Lift rated load 4–8 inches from the ground and measure girder deflection
- Compare measured deflection to manufacturer data
- Conduct brake tests by lowering under control and verifying stopping distances
- Test emergency brake systems (dynamic, eddy current, regenerative) per manufacturer requirements
- Perform proof load test at 125% of rated load across the crane’s full working range
- Where multiple cranes share the runway, conduct simultaneous load tests
- Measure combined runway deflection and verify against code requirements
Following completion of the tests:
- Park and secure the crane, then de-energize and lock out power
- Inspect runway fasteners, alignment, and structural supports
- Check all electrical enclosures, wiring, and protective devices
- Examine wire ropes, sheaves, and drums for wear or damage
- Confirm guards are installed on all moving parts
- Record all findings, noting any deficiencies and required corrective actions
- Complete and file the official load test report