To prevent fatigue and damage to the chain of a lever type chain crane, comprehensive measures need to be taken from six aspects: materials and manufacturing, installation and commissioning, operation specifications, maintenance, environmental management, and personnel training. The specific measures are as follows:

1、 Material and Manufacturing Quality Control

Select high-quality materials

The chain should be made of high-strength alloy steel (such as 20Mn2, 25MnV, etc.) to ensure that the tensile strength, yield strength, and toughness meet the standards (such as GB/T 20947 "Short Loop Chains for Lifting Use").

Avoid using inferior steel or recycled materials to prevent internal defects such as pores and inclusions from causing fatigue crack initiation.

Optimize manufacturing process

Adopting heat treatment processes such as quenching and tempering to improve the wear resistance and fatigue resistance of the chain, ensuring uniform surface hardness.

Strictly control the dimensional tolerance of the chain link to avoid local stress concentration caused by excessive assembly clearance.

2、 Correct installation and debugging

Standardize the installation process

Ensure that the connection between the chain and components such as hooks and pulleys is firm, avoiding looseness or misalignment.

Adjust the tightness of the chain to avoid being too tight (increasing friction) or too loose (causing chain jumping or jamming).

Load testing and calibration

After installation, conduct no-load and load tests to verify whether the chain runs smoothly and whether the brake is sensitive and reliable.

Calibrate the limit device to prevent excessive stretching caused by chain overtravel operation.

3、 Standardize operational behavior

Avoid overloading and unbalanced loading

Strictly adhere to the rated load and prohibit overloading (such as lifting a 5-ton crane with a nominal capacity of 6 tons).

Ensure even distribution of load and avoid excessive force on one side of the chain caused by unbalanced load.

Reduce impact load

Smooth lifting or lowering during operation, avoiding sudden acceleration or emergency stop, and preventing the chain from experiencing instantaneous overload.

When lifting heavy objects, slowly lift them to a height of 10-20cm above the ground and confirm that there are no abnormalities before continuing the operation.

Do not pull or hang diagonally

Keep the angle between the chain and the vertical direction ≤ 5 ° to avoid chain twisting or lateral force caused by diagonal pulling.

When using guide pulleys or steering devices, ensure that they are installed in the correct position to reduce chain friction.

4、 Regular maintenance and upkeep

routine inspection

Before each use, check the surface of the chain for cracks, deformation, or wear (if the diameter of the chain link decreases by ≥ 10%, it needs to be replaced).

Confirm the lubrication status of the chain, replenish lubricating oil (such as lithium based grease) in a timely manner, and reduce dry friction.

Regular in-depth maintenance

Thoroughly clean the chain every quarter to remove oil stains and impurities, and check whether the internal chain links are loose.

Replace the severely worn chain links locally to avoid the entire chain being scrapped.

Storage Management

When not in use for a long time, clean the chain and apply anti rust oil. Store it in a dry and ventilated place to avoid rusting in a humid environment.

When hanging for storage, use a dedicated bracket to prevent chain deformation.

5、 Environmental adaptability management

Protection against corrosive environments

When used in corrosive environments such as chemical and marine environments, stainless steel chains or galvanized chains should be selected, and anti rust coatings should be added.

Regularly clean the corrosive substances on the surface of the chain to prevent electrochemical corrosion.

High temperature environment response

When working at high temperatures, use heat-resistant chain materials (such as nickel based alloys) and strengthen cooling measures (such as spray cooling).

Avoid prolonged continuous operation to prevent performance degradation of the chain due to thermal expansion.

Dust environment protection

When used in dusty environments such as mines and cement, install dust covers or sealing devices to reduce dust from entering the interior of the chain.

Regularly clean the dust in the gaps of the chain to prevent further wear and tear.

6、 Personnel training and assessment

Operational skills training

Train operators on chain structure, fatigue mechanism, and damage identification to enhance their risk awareness.

Simulate fault scenarios (such as chain breakage or jamming) and train operators in emergency response capabilities.

Maintenance capability assessment

Regularly assess the skills of maintenance personnel in chain inspection, lubrication, and replacement to ensure maintenance quality.

Establish and maintain archives to record the usage time, load history, and maintenance records of the chain, providing a basis for life assessment.

The main equipment produced by Hebei Makita: stage electric hoist, electric chian hoist, wire rope electric hoist，Hand chain hoist, lever hoist, pneumatic hoist and other lifting equipment