Load Chain (Lifting Chain) is an important and necessary loading device for the crane machines. It can adjust the length of chain according to the difference load heights. It plays an important role in the crane working efficiency and range.

According to the applications, it can be divided into 4 kinds of load chains (lifting chains) :

1.Transmission Chain: It is mainly used for power transmission.

2.Conveyor Chain: It is mainly used for conveying products.

3. Dragging Chain: It is mainly used for dragging and lifting things.

4. Professional Special Chain: It is mainly used for professional special devices with special function and structure chains.

No matter what the applications they are used for, the chains all need maintenance and regular examinations.

Load chain (Lift chain) appearance inspections:

  • Check the inner or outer chain plates get deformed, crack, rusted or not.
  • Check the pins get deformed, flexible, rusted or not.
  • Check the rollers get crack, destroyed, over-worn or not.
  • Check the connection joints get deformed and flexible or not.
  • Check if there is abnormal sound or shaking, chain lubrication is good or not.

The chain length precision measurement.

Wash and clean the chains before measured.

Put the chain on the two sprockets with something supporting up and down.

The measured chain should be under the condition of stopping 1 minute with min. tensile load of 1/3 force.

When measuring, the chain should be tested with required measuring load to keep the up and down chains tensile with normal interdigitation.

Measure the centre distance of the two sprockets.

Measure the chain extension

  • The chain should be measured under a certain tension to avoid the clearance.
  • The chain should be measured at 6-10 link to avoid deviation.
  • Measure the size of roller’s inner side L1 and outer side L2 to get Judgement Size L= (L1+L2)/2.
  • Chain extension = Judgement Size – datum length/datum length * 100%.
    Datum length = Chain pitch * pitch number

How to judge Scrapping load chains ?

  • The attrition value that the chain allowed is not more than 10% of the round-link chain stick material diameter or auxiliary device thickness.
  • If the main chain ring bends over 10 angle degree from the main ring non-bend plate, it should be scrapped.
  • If any points of the chain get cracks, bends, or stocked that cannot be shut out, it should be scrapped.
  • The permanent extension of chains and single ring should be 5% less than the original length.

Maintenance of Load Chain in the Daily Use:

Chain wheel should be fixed steady on the axle without deflection and shaking. The end face of 2 chain wheels in the same driving parts group should be in the same graph. When the center distance is less than 0.5m, it allows 1mm difference; the center distance of chain wheel is more than 0.5m, it allows 2mm difference. But do not allow the friction to the chain wheel teeth flank. If the big difference of the 2 chain wheels will cause detaching and speed abrasion. We should check and adjust the deflection.

Load chain tightness should be proper. Over-tight chain will increase the power loss, the bearing will be caused abrasion. Over-released chain will cause detaching and bouncing. The standard tightness should be: lift the chain from the middle or press down, the center distance of 2 chain wheels is about 2%-3%.

New chains may be too long after using that is difficult to adjust, we can reduce some chain links, but must be even number. Chain link should be through the back, locking plate is outside, the lock sheet opening should be opposite from the turning direction.

If the chain wheels get serious abrasion, you should change new chains and new wheels to ensure the good tooth contact. You can not only change new chain or `new wheel, which will speed the abrasion of new chains and wheels. When the tooth contact surface gets some certain abrasion, you should change with another side (it should be adjustable surface for use), to keep its durability.

You can not mix the old and the new chains for use, otherwise it can be easy to be impacted and broken.

Load chain should add enough lubrication oil, the oil must go into the rollers and inner gaps to make them work properly with less abrasion.