ISO 23774:2020 Crane Test Methods for Bridge & Gantry Cranes
ISO 23774:2020 "Cranes — Bridge and Gantry Cranes — Test Methods" is the comprehensive standard governing test procedures for bridge and gantry cranes. It defines the procedures, step-by-step methods, and acceptance criteria for static load tests, dynamic load tests, safety device inspections, and overall machine performance evaluation. Static load tests verify structural strength, dynamic load tests confirm mechanism reliability, and safety device checks validate the integrity of protective functions.
Static Load Test Procedure
Before conducting the static load test, a comprehensive inspection of the crane must be performed to confirm that all mechanisms, safety devices, and lubrication are in proper working order. Test weights must be within their calibration validity period with a mass deviation of ≤±1%. The test begins by loading to 100% of the rated load, positioning the fully loaded trolley at mid-span of the main girder, and holding for ≥10 minutes. A precision level instrument with an accuracy of ±0.1 mm is used to measure mid-span deflection δmax. Under rated load, main girder deflection must not exceed L/400 to L/500. After unloading, residual deformation δr is measured and must not exceed 20% of the total deflection δmax. For the overload test, the crane is loaded to 1.25 times the rated load and held for ≥15 minutes. All weld seams must show no cracks, bolts must remain tight, and no permanent structural deformation is permitted. For gantry cranes, outrigger elastic deformation must also be checked, with horizontal displacement not exceeding H/500.
Dynamic Load Test Procedure
The dynamic load test is conducted at 1.1 times the rated load with combined motion testing of all mechanisms. Hoisting and lowering are each performed at least 3 times over the full travel range, with each lift height ≥1 m and brake slip distance ≤100 mm. The trolley travels the full length of the crane bridge at least 3 times to verify smooth operation along the rails. The crane bridge also travels its full stroke at least 3 times, with motor current fluctuation checked to remain within ±10%. Safety device verification includes: the load moment limiter (LML) must provide an audible and visual warning at 90% load and automatically stop hoisting and luffing at 100% load. The height limit switch must trigger a warning 0.5 m before the hook reaches its highest position and stop the hoist at 0.3 m. Travel limit switches must stop the crane 1 m before the end of the rail in both directions. For the emergency stop test, the Emergency Stop Button is pressed during full-speed operation, and the control system must respond within ≤0.5 s. Reducer temperature rise must not exceed 40°C, motor temperature rise must not exceed 60°C, and brake surfaces must show no signs of overheating or discoloration.
| Test | Load | Operation | Acceptance |
|---|---|---|---|
| static load | 1.25Times | Mid-span Pressure Holding15min | Residual≤20% |
| overload | 1.25Times | Mid-span Pressure Holding | None Crack/permanent deformation |
| dynamic load | 1.1Times | Hoisting / Lifting+Each Travel3Cycle | Braking≤100mm |
| emergency stop | 1.1Times | Full Speedemergency stop | ≤0.5sSway≤15° |
| safety device | Each Traveloperating conditions | All Operations | Torque/limit switch/Alarm |
Safety Device Inspection and Testing
During the load test, a comprehensive inspection of all safety devices must be carried out in parallel. The load moment limiter (LML) is tested by progressively increasing the load to 90% of the rated load to confirm the early warning function activates correctly, then to 100% to verify automatic stop of hoisting and luffing, followed by reducing the load below 90% to confirm the automatic reset. For limit switches, manual triggering verifies contact sensitivity and buzzer alarm operation. Brake performance is checked under rated load, with static braking slip not exceeding 100 mm and emergency braking distance within the allowable range. All safety device inspection records are attached to the Test Report. Before delivery, every Kelude overhead and gantry crane undergoes the full static and dynamic load test procedures specified in ISO 23774:2020, and a Load Test Report along with safety device inspection records is issued for each unit.
| Device | inspection method | Acceptance Criteria |
|---|---|---|
| Load moment limiter (LML) | 90%/100%/110%Step-by-step | 90%early warning/100%Stop |
| Lifting Capacity Limiter / Load Limiter | Load to105% | Stop Hoisting / Lifting |
| Height Limit Switch | Hook Upward Trigger | 0.5m/0.3m |
| Travel Limit Switch | Large Cross Travel / Trolley Travel Upward Trigger | Before End Limit1m |
| Brake | 1.1Times Braking | Droop≤100mm |
Gantry Crane Testing: FAQ
Q: What is the static load test procedure?
A: Hold 100% of the rated load for 10 minutes, then release. Next, hold 125% for 15 minutes. Deflection must not exceed L/400 to L/500, with residual deformation limited to 20% of the measured deflection. No cracks or permanent deformation are permitted.
Q: What are the dynamic load test requirements?
A: Perform three hoisting and three travel cycles at 1.1 times the rated load. Braking deceleration must keep the load slide within 100 mm. The emergency stop must bring the crane to a halt within 0.5 seconds, with load swing limited to 15°. Motor temperature rise must not exceed 40°C.
Q: What tests are specific to gantry cranes?
A: Outrigger elastic deformation must not exceed H/500. The diagonal difference between the gantry legs must remain within 2 mm during load application.
Q: What does the test report include?
A: The report records the test date, applied loads, measurement data, safety device inspection results, and the final conclusion. It requires signatures from both parties. Kelude supplies a test report with every crane at the time of factory delivery.
