I. Preparations Before Adjustment
1. First, troubleshoot fundamental issues: Verify that the conveyor belt has no cracked splices, worn rollers, or oil/grease buildup on its surface, to prevent slippage or belt misalignment from occurring even after adjustment.
2. Establish tension reference standards: For standard lightweight PVC conveyor belts, a recommended initial tension of 5–10 N/mm (calculated based on belt width) is advised. For heavy-duty or long-distance conveyors, use the upper end of this range. During adjustment, do not exceed the recommended maximum tension value to avoid accelerating belt wear.
II. Adjustment Methods for Different Tensioning Devices
1. Screw-type Tensioning Devices (Most common on small, short-distance conveyors)
First, loosen the fixing nuts located on both sides of the tensioning device.
Rotate the tensioning bolts on both sides *uniformly and simultaneously*: If increased tension is required, rotate the bolts inward in unison to pull the roller backward, thereby tightening the belt. If the tension is excessive, rotate the bolts in the opposite direction to allow the roller to move forward, thereby loosening the belt.
Throughout the adjustment process, ensure that the inward/outward travel distance of the bolts on both sides remains identical. This guarantees that the roller remains parallel and that tension is balanced across the belt width, preventing misalignment caused by uneven tension.
2. Gravity (Counterweight) Tensioning Devices (For long-distance/heavy-duty conveyors)
Check the position of the counterweight: If the counterweight has already reached its lowest limit yet tension remains insufficient, additional weight blocks must be added.
If the counterweight position is too high-indicating excessive tension-simply remove weight blocks gradually until the desired tension is achieved.
After adjustment, position the counterweight near the middle of its travel range to reserve sufficient compensation space for future belt elongation.
3. Carriage-type / Hydraulic Tensioning Devices
Carriage-type Tensioning: Adjust the position of the tensioning carriage; tension is regulated by altering the carriage's travel distance. Once the desired position is reached, simply engage and lock the positioning pins to secure the carriage.
Hydraulic Tensioning: Directly adjust the pressure value within the hydraulic system. Set the pressure to the specific parameter corresponding to the required belt tension, then engage the pressure-holding mechanism to lock the setting. III. Post-Adjustment Verification Criteria
Once the adjustment of the fixtures is complete, start the equipment and run it under no-load conditions for 30 minutes.
The adjustment is deemed successful if the following conditions are met:
1. During operation, there is no slippage or frequent belt misalignment;
2. In the return section, the sag of the conveyor belt does not exceed 2% of the idler spacing;
3. When manually pressing down on the center of the conveyor belt, the deflection is between 3–5 mm, and the belt rebounds quickly upon release.
Key Considerations
1. PVC conveyor belts naturally undergo stretching and slackening after installation. It is recommended to re-inspect and fine-tune the belt tension 1–2 weeks after the initial adjustment run to prevent accumulated slack from causing slippage.
2. If slippage persists even after adjusting the belt to its maximum tension, the issue is not related to tension. In this case, check whether the problem is caused by worn rollers or oil/grease buildup on the roller surfaces; clean or replace the rollers as necessary.
