Diagnosis and correction of obstacles in the chain conveyor: chain stretching, gear fatigue, lack of lubrication and material accumulation

1. Problem description and scope

This is a guide to diagnosing chain conveyor obstructions caused by chain stretch, gear fatigue, insufficient lubrication, and material build-up. Issues are classified as critical and medium because they can cause production stoppages, damage to equipment, and danger to personnel.

2. Preventive measures

Use special protective clothing (PPE):

• Gloves with grease resistance
• Glasses with protection against dust
• Pants with resistance to mechanical damage
• Cascade

Perform lockout/tagout (LOTO) before work:

• Power outage
• Installation of the lock on the switch
• Confirmation of absence of voltage

Be careful when working with accumulated energy load:

• After disconnection, according to the instructions, allow time for discharge
• Use a voltage tester before opening

3. Diagnostic tools are required

4. Check before starting diagnostics

5. Systematic diagnostic flow chart

1. Symptom: Conveyor shuts down due to overload
1. Check vibration level (range 0-5 mm/s)
1. If the value is < 2 mm/s, go to the next step
2. If the value is > 4 mm/s, diagnose the gears
2. Check chain tension (range 0-5mm)
1. If the stretch is < 1.5 mm, go to the next step
2. If the stretch is > 3 mm, perform circuit diagnostics
2. Symptom: Conveyor does not work
1. Check the power supply
1. If there is no power supply, perform diagnostics of the electrical system
2. If power is present, diagnose the mechanical system

6. Matrix of causes of defects

7. Detailed analysis of the causes of defects

7.1 Chain stretching

Reason: Due to constant load and lack of lubrication, the chain becomes stretched. Stretching more than 3 mm causes an increase in the distance between the gears, which leads to overload.

Diagnosis: Measure the distance between the chain and the gears. If the stretch is greater than 3mm, consider this as the underlying cause.

Consequences: Re-increasing the load can lead to rolling of the chain or its complete damage.

7.2 Gear fatigue

Reason: The stability of the gears decreases due to continuous loading and insufficient lubrication. Vibration greater than 4 mm/s indicates fatigue.

Diagnosis: Measure the vibration. If the value is greater than 4 mm/s, recognize this as the root cause.

Consequences: Gear fatigue causes them to knock out, which can cause an accident.

7.3 Insufficient lubrication

Reason: Lubrication is critical to reduce friction and wear. Its absence leads to increased friction and fatigue.

Diagnosis: Check the lubrication level. If it's less than 100%, recognize that as the root cause.

Consequences: Insufficient lubrication leads to rapid wear and tear of the mechanism.

8. Step by step repair procedure

8.1 Correction of chain stretching

1. Turn off the power and do LOTO.
2. Measure the current chain length.
3. Increase the number of links or install a new chain.
4. Resize the gears if necessary.
5. Check the lubrication and set the level to 100%.
6. Measure distance and vibration again.

8.2 Gear fatigue correction

1. Turn off the power and do LOTO.
2. Measure the vibration and check the degree of fatigue.
3. Replace damaged gears with new ones.
4. Check the lubrication and set the level to 100%.
5. Measure vibration and distance again.

8.3 Correction of insufficient lubrication

1. Turn off the power and do LOTO.
2. Check the lubrication level.
3. Set the lubrication level to 100%.
4. Measure vibration and distance again.

9. Preventive measures

10. Spare parts and components

Learn more about our spare parts at: https://www.unitecd.com/e-catalog/

11. List of references

• ISO 10816-1:2019 – Vibration measurement
• EN 13155:2017 – Requirements for chains
• DSTU 2133:2004 – Requirements for gears
• UNITEC-D technical manuals for conveyors