Load testing is one of the most critical steps after installing a Rubber Tired Gantry (RTG) crane. It ensures that the crane operates safely, meets design specifications, and performs reliably under real working conditions. Whether the crane is used for container handling, logistics yards, or manufacturing terminals, load testing verifies that all structural components, mechanical systems, electrical systems, steering modes, and safety protections function correctly before being put into service. This article provides a complete guide to load testing procedures after RTG crane installation, including preparation, testing methods, safety protocols, and post-test evaluation.

1. Importance of Load Testing After RTG Crane Installation

Load testing serves multiple functions in the commissioning stage:

1.1 Validate Structural Integrity

The RTG crane’s steel frame, girders, spreader, trolley system, and lifting mechanisms must withstand rated loads without deformation, instability, or abnormal vibrations. Load testing confirms compliance with design standards such as FEM, CMAA, ISO, or GB/T safety codes.

1.2 Ensure Safe Operation

A newly installed crane may have uncalibrated components, loose bolts, misalignment, or incorrect limit settings. Load testing identifies these issues under controlled conditions before real operation.

1.3 Verify Performance of Mechanical and Electrical Systems

Critical systems evaluated during load testing include:

Hoisting mechanism

Trolley travel

Gantry travel

Steering and braking systems

PLC control logic

Anti-sway system

Sensors and safety interlocks

1.4 Ensure Compliance With Regulations

Most ports, factories, and container yards require load testing certification to authorize crane operation.

1.5 Build Customer Confidence

Load testing demonstrates that the crane is safe, reliable, and ready for continuous heavy-duty work.

2. Preparations Before RTG Load Testing

Before load testing begins, a thorough preparation stage ensures safe and accurate test results.

2.1 Installation Verification

A complete inspection must confirm that the rubber tire gantry crane is installed according to manufacturer drawings and specifications. This includes:

Visual inspection of girders, beams, and welds

Checking torque of all bolts and connections

Verification of rail alignment for trolley travel

Inspection of hydraulic lines (if applicable)

Confirmation of cable routing, festoon system, or cable reel installation

2.2 Electrical System Commissioning

Electrical preparation includes:

Testing insulation resistance

Validating PLC logic and safety circuits

Setting travel limits, height limits, and speed parameters

Checking power supply voltage, grounding, and earthing

2.3 Functional Testing (No-Load Testing)

Before adding load, the crane must pass basic functional tests:

Hoisting, lowering, and inching

Trolley travel end-to-end

Gantry travel with different steering modes (straight, 90°, pivot, diagonal)

Emergency stop

Brake response

Anti-sway or sway control calibration

Overload protection

2.4 Safety Preparation

All testing equipment must comply with recognized safety standards. Prepare:

Certified test weights or water bags

Slings, shackles, and spreader equipment

A safety exclusion zone around the test area

Fire extinguishers, radios, and PPE (helmets, gloves, reflective vests)

A test leader and team roles clearly assigned

3. Types of Load Testing for RTG Cranes

Load testing of RTG cranes generally includes two major categories:

3.1 Static Load Test

The static load test checks structural strength and stability when the crane supports a non-moving, overweight load.

Typical requirements:

Test load = 1.25 × rated capacity (according to FEM/ISO standards)

Lifting load to maximum height

Hold load for 10–20 minutes

What to inspect:

Beam deflection

Structural deformation

Hoist motor temperature

Wire rope behavior

Brake holding performance

Any abnormal noises or vibrations

3.2 Dynamic Load Test

This test measures how the rubber wheeled gantry crane behaves under operational movements such as lifting, traveling, and lowering.

Typical requirements:

Test load = 1.1 × rated capacity

Perform repeated cycles of:

Hoisting and lowering

Trolley travel with load

Gantry travel in multiple steering modes

Emergency stops

Regular starts and stops

What to evaluate:

Smoothness of movement

Impact load effect

Acceleration and deceleration

Brake performance under motion

Steering stability under load

PLC response time and system reliability

4. Load Testing Procedure

Step 1: Briefing and Safety Meeting

Explain the testing process, roles, hazards, and communication signals.

Step 2: Set Up Test Load

Use certified test weights or water bags attached to the spreader. Confirm:

Safe working load of slings

Correct locking of the spreader twistlocks

Balanced distribution

Step 3: Perform Static Load Test

Lift load to specified height.

Hold for prescribed duration.

Observe for structural changes, cable tension, and motor performance.

Check deflection readings and compare with manufacturer limits.

Step 4: Conduct Dynamic Load Test

Run the RTG through operational cycles:

Lift and lower

Trolley forward and backward

Gantry travel under different steering modes

Simulate normal and emergency braking

Test anti-sway system performance

Step 5: Test Safety Devices

Validate safety systems:

Overload limiter

Height limit switch

Travel limit switches

Park brake

Anti-collision sensors (if installed)

Gantry skew control

Step 6: Record All Data

Testing engineers should document:

Load values

Temperatures

Vibration levels

Deflection measurements

Electrical readings

Travel speed measurements

Step 7: Post-Test Inspection

After unloading:

Inspect steel structure again

Check connections and bolt torque

Review hoist brake condition

Inspect wire ropes for distortion

Examine tyres for deformation or overheating

5. Acceptance Criteria for RTG Crane Load Testing

An RTG crane passes load testing when:

5.1 Structural Requirements

Deflection falls within standard limits

No cracks, weld failures, or deformation

Tyres remain stable without skidding or excessive compression

5.2 Mechanical & Electrical System Requirements

Hoist brake holds load securely

Motors do not overheat beyond design threshold

Trolley and gantry movements are smooth

Steering system remains stable under load

Limit switches operate accurately

5.3 Safety System Requirements

Overload protection triggers correctly

Emergency stop engages immediately

Anti-sway system reduces load swing effectively

Anti-collision system responds within required detection range

When all criteria are met, the crane is approved for commissioning and normal operation.

6. Documentation and Certification

After completing the load test:

A detailed load test report must be prepared

Photos and videos of the test should be stored

Independent inspectors (if required) sign the certification

Maintenance team receives a checklist for follow-up adjustments

Documentation usually includes:

Test procedures

Load values and measured data

Structural measurements

Safety device performance

Technician signatures

Final acceptance conclusion

7. Importance of Post-Load Test Adjustments

Even when the crane passes testing, minor adjustments are often necessary:

Fine-tuning limit switches

Re-tensioning wire ropes

Aligning trolley rails

Calibrating PLC parameters

Adjusting steering angles

Rechecking bolt torque after the load test

These adjustments extend the crane’s lifespan and improve reliability.

Conclusion

Load testing is a critical step in the commissioning of a Rubber Tired Gantry crane. A well-executed testing process ensures the crane can handle its rated capacity safely, perform reliably under real-world operating conditions, and comply with international standards. By following systematic load testing procedures—including preparation, static and dynamic testing, safety verification, and post-test inspection—owners and operators can ensure the crane is ready for efficient and dependable service from day one. Proper load testing not only safeguards equipment investment but also enhances operational safety, productivity, and long-term performance of the RTG crane.