Leaf Chain Wear and Inspection

Circumferential Wear on Leaf Chain Side Plates

The most common cause of this is routine wear from use over time. The solution is to measure the height of the side plate (H). If the wear exceeds 5% of the original side plate height, it is time to replace the leaf chain.

Oblique Wear of Plate and Pin Head

This is typically the result of a misalignment between the leaf chain guide and pulleys. The solution to this issue is to check the machine's alignment and make as necessary adjustments. When this occurs, it is recommended to replace the chain if the wear has affected the rivets on the outside plates of your leaf chain. For assistance in determining whether a chain replacement is necessary, please get in touch with our customer service team.

Stiff Leaf Chain Links

Stiff links can be the result of several primary issues, such as dust or foreign substances within the bending portion of the chain assembly, corrosion and rust, or a bent pin. 

Possible Solutions:

• Dust or Foreign Substances – Often, this can be resolved with washing and re-lubricating the chain. We supply a range of chain lubricants that work perfectly on any leaf chain size.
• Corrosion and Rust – When it comes to corrosion on leaf chains to the point of causing the chain to be stiff, it is typically recommended to replace the chain due to the probability of a loss in strength and fatigue load capacity. Additionally, a chain that is sized incorrectly won’t perform as intended and may cause issues with other aspects of the equipment.
• Bent Pin or Pins – If this occurs, the chain must be replaced immediately. Pin bending on a leaf chain typically indicates that the chain was overloaded or a subpar chain is being used.

Abnormal Protrusion or Rotation of Pin Head

This is usually caused by excessive tension, overloading, or insufficient lubrication. The solution would be to replace the chain as its capacity is severely degraded. When using a new chain, ensure it is adequately lubricated and avoid overloading.

Leaf Chain Elongation

This typically occurs throughout the lifespan of a leaf chain and is a typical symptom of long-term use. However, if excessive elongation occurs within a short timeframe after the leaf chain installation, there may be an issue related to the chain's quality or overloading. A good reference point for chain replacement is when the chain elongation reaches 1.03 times its original length (3%). It’s important to note that when a chain is 3% elongated from its standard length, the tensile strength is diminished by 18%.

Cracked Leaf Chain Link Plates (Type 1)

In this specific example, the crack occurs from the hole in the link plate in the direction perpendicular to the tension direction. This is a clear indication that the load put on the chain exceeded the allowable limits of the chain. The solution would be to replace the leaf chain with one of higher load capacity, or to lower the dynamic shock load on the chain.

Cracked Leaf Chain Link Plates (Type 2)

This example shows when the cracks are oblique in direction against the tension direction. This is more than likely the result of heavy rust or corrosion on the material. The solution would be to replace the chain. If it is in a corrosive environment, consider an anti-corrosive leaf chain option, such as a coated leaf chain.

Broken Elongated Chain Plate

When this occurs, it is a clear indication of an overload. The solution would be to replace the entire chain and eliminate the cause of the overload or equip the machine with a higher load leaf chain. Something important to note with failures like this is that the entire section of the chain will need to be replaced. When chain failure occurs under load, it typically indicates that micro fatigue cracks exist throughout other components of the chain that are not visible. Do not repair a leaf chain section by way of connecting links or small pitch sections.

Enlarged Plate Hole

This is another indication that the leaf chain was overloaded. The solution would be to replace the chain and either eliminate the overloading that occurs in the future or increase the leaf chain size to one of higher capacity.

Corrosion or Pitting on Leaf Chain

When leaf chains begin to show signs of corrosion, it is typically due to a corrosive environment or specific circumstances. The solution would be to replace the chain with a new one that has an anti-corrosive coating. Alternatively, please speak to one of our product specialists about anti-corrosive chain lubricants or other solutions.

Leaf Chain Pin Wear

This is a normal wear factor that occurs over time with use. Once the pins begin to show signs of wear or deformation, it is recommended to replace the chain as its integrity is severely compromised.