Regular inspection of your roller chain is crucial for maintaining performance, ensuring safety, and extending equipment life. This guide will walk you through the key steps to inspect roller chains effectively, identify wear and elongation, and avoid unexpected equipment failures.
Check List:
Noise or Vibration
- Abnormal Condition and Inspection – Unusual noise or vibration occurs during operation.
- Correction – Check the chain’s tension, tightness, and wear. Confirm whether the chain is hitting any surrounding parts during operation.
Chain Tightness
- Abnormal Condition and Inspection – Rotate the sprocket to tighten one side of the chain. Measure the mid-span movement of the other side as below graph S-S’ slack span.
2-1. When the angle is less than 45° between center line of the sprockets and the horizontal, the amount of S-S’ movement should be 2% ~ 6% of shafts center distance (A – B).
2-2. When the angle is more than 45°, the amount of S-S’ movement should be 1% ~ 3% of A – B.
2-3. In the following conditions, the amount of S-S’ movement should be 1%~ 3% of center distance (A – B).
◎ Distance between the shafts is more than 1 meter.
◎ Frequent start-stop under heavy load
◎ Chain is forward and reverse conversion motion.
- Correction – Adjust the chain to the correct tightness or use an idler.
Lubrication
- Abnormal Condition and Inspection – Visually check the appearance of the chain. If black or rust-colored powder is present between the links, it indicates that the lubricating oil inside the links is insufficient.
- Correction – Re-lubricate the chain. Check the chain wear and see if there is tight joints, rollers proper rotation and turning pins. Replace the whole chains if necessary.
Rollers
- Abnormal Condition and Inspection – Check if the roller can be rotated freely by turning it by hand. Visually inspect the rollers for damage, cracks or wear.
- Correction – Check if lubricating oil is sufficient. Re-lubricate if necessary. If the rollers are damaged or cracked, the chain must be replaced.
Chain wear inspection
Image source: CTS Roller Chain Measure Tools
- Abnormal Condition and Inspection – After the chain is used, the chain length would extend because of the friction and wearing between pins and bushings. By measuring the elongation, we can know if whether the chain has reached the service life or not.
- How to measure chain elongation: Straighten the chain and apply some force to eliminate the gap between the chain links. Measure the length of 6~10 links with a caliper, as shown in the figure below.
The elongation limit (wear rate) of chain service life is related to the number of large sprocket teeth. Please refer to below table:
| Large sprocket teeth | Elongation limit |
| Less than 60 teeth | 1.5% |
| 61~80 teeth | 1.2% |
| 81~100 teeth | 1.0% |
| 101~110 teeth | 0.8% |
- Correction – If elongation reaches the limit, please replace the chain.
Tight joints
- Abnormal Condition and Inspection – Twist the chain links up and down to see if the chain can work freely. If the chain is stuck cannot twist freely, it shows that the chain may have tight joints.
- Correction – Please clean the chain if dirt or foreign substance is packed in joints. Check whether the chain is worn out. Check the lubrication status and re-lubricate if necessary. If there is no improvement after re-lubricating the chain, please replace the chain.
Turned pins
- Abnormal Condition and Inspection – Visually inspect the direction of the pin riveting and check if there is any rotation.
- Correction – Check whether the chain is overloaded or insufficiently lubricated. If pins rotate, please replace the chain.
Enlarged Holes
- Abnormal Condition and Inspection – Check if link holes have become elongated (oval-shaped).
- Correction – If caused by overloaded, replace the chain with larger size or higher-strength chain.
Cracked and fractured plates
- Abnormal Condition and Inspection – Visually inspect if there are cracked and fractured plates.
- Correction – If the chain is overloaded, replace the chain with larger size or stronger chain. For corrosive environments, replace with corrosion-resistant chain.
Worn plates
- Abnormal Condition and Inspection – Check the plate height (H). Side plate wear should not exceed 5% of H. It would influence the strength of the chain.
- Correction – Use chain guides or wear strips. Replace the chain if wear exceeds 5%.
Conclusion
Proper roller chain inspection is key to ensuring reliable performance, minimizing downtime, and extending the life of your machinery. By regularly checking for wear, alignment, lubrication, and tension, you can prevent unexpected failures and keep your operations running smoothly. At Maxtop, we are committed to providing high-quality roller chains. Following the right inspection practices is not just good maintenance—it’s a smart investment in your equipment’s longevity and efficiency.
FAQ
Q1: How often should I inspect my roller chain?
A1: In general, roller chains should be inspected every 500–1000 operating hours, or monthly for high-duty applications.
Q2: What tools do I need to measure chain elongation?
A2: A vernier caliper or chain wear gauge is recommended.
Q3: What is the maximum allowed elongation before replacement?
A3: Generally, if elongation exceeds 3%, the chain should be replaced.
