Conveyor belts Problems &Solutions

PROBLEM /CAUSE in order of probable occurrence with Reference solutions

1. The conveyor runs to one side at a given point on the structure

• 1. Structure not level: Level structure in the affected area.
• 2. The buildup of material on idlers: Remove accumulation; Improve maintenance. Install scrapers or other cleaning devices.
• 3. Sticking idlers: Free idlers and improve maintenance and lubrication.
• 4. Idlers or pulleys out of square with the center line of the belt: Readjust idlers in the affected area.
• 5. Conveyor frame or structure crooked: Straighten in the affected area.
• 6. Idler frame not centered on belt: Readjust idlers in the affected area.

2. A particular section of the belt runs to one side at all points on the conveyor

• 1. Belt not joined squarely: Remove the affected splice and resplice.
• 2. Bowed belt: For new conveyor belts this condition should disappear during break-in; In rare instances belt must be straightened or replaced; Check storage and handling of belt rolls.

3. The belt runs to one side for a long distance or the entire length of the conveyor

• 1. Belt running off-center around the tail pulley and through the loading area: Install training idlers on the return run before the tail pulley.
• 2. Off-center loading or poor loading: Adjust the chute to place the load on the center of the belt; Discharge material in the direction of belt travel at or near belt speed.
• 3. Buildup of material on idlers: Remove accumulation; Improve maintenance. Install scrapers or other cleaning devices.
• 4. Idlers or pulleys out of square with the center line of the belt: Readjust idlers in the affected area.
• 5. Conveyor frame or structure crooked: Straighten in the affected area.
• 6. Idler frame not centered on belt: Readjust idlers in the affected area.

4. The belt runs off at the tail pulley.

• 1. The Belt running off-center around the tail pulley and through the loading area: Install training idlers on the return run before the tail pulley.
• 2. Material spillage and buildup: Improve loading and transfer conditions; Install cleaning devices; Improve maintenance.
• 3. The idlers or pulleys out of square with the center line of the belt: Readjust idlers in the affected area.

5. The belt runs off at the head pulley.

• 1. Pulley lagging worn: Replace pulley lagging.
• 2. Material spillage and buildup: Improve loading and transfer conditions; Install cleaning devices; Improve maintenance.
• 3. The idlers or pulleys out of square with the center line of the belt: Readjust idlers in the affected area.
• 4. Idler frame not centered on belt: Readjust idlers in the affected area.

6. Belt slip

• 1. Insufficient traction between belt and pulley: Lag drive pulley: Increase belt wrap: Install belt cleaning devices.
• 2. Pulley lagging worn: Replace pulley lagging.
• 3. Counterweight too light: Add counterweight or increase screw take-up tension to value determined from calculations.
• 4. Material spillage and buildup: Improve loading and transfer conditions; Install cleaning devices; Improve maintenance.
• 5. Sticking idlers: Free idlers and improve maintenance and lubrication.

7. Belt slip on starting.

• 1. Insufficient traction between belt and pulley: Lag drive pulley: Increase belt wrap: Install belt cleaning devices.
• 2. Counterweight too light: Add counterweight or increase screw take-up tension to value determined from calculations.
• 3. Pulley lagging worn: Replace pulley lagging.

8. Excessive belt stretch.

• 1. Improper belt installation causing apparent excessive belt stretch: Pull belt through counterweight with a tension equal to at least empty running tension: Run belt in with mechanical fasteners.
• 2. Improper initial positioning of counterweight in its carriage causing apparent excessive belt stretch: Consult Marsbelts for recommended initial position.DIN22101 section 10.3 recommended the ratio be≤3
• 3. Insufficient counterweight travel: Consult Marsbelts for recommended minimum distances.
• 4. Tension too high: Increase speed, same tonnage; Reduce tonnage.same speed: Reduce friction with better maintenance and replacement of damaged idlers: Decrease tension by increasing arc of contact or go to lagged pulley; Reduce CWT to minimum amount.
• 5. Counterweight too heavy: Lighten the counterweight to the value required by calculations.
• 6. System under-belted: Recalculate belt tensions and select a proper belt.

9. Grooving, gouging, or stripping of top cover.

• 1. Skirt boards improperly adjusted or of the wrong material: Adjust skirt board supports to a minimum of 25mm between metal and belt with a gap increasing in direction of belt travel: Use rubber skirt board (not old belt)
• 2. Belt spanking down under load impact: Install impact idlers.
• 3. Material hanging up in or under the chute: Improve loading to reduce spillage; Install baffles; widen chute.
• 4. Impact of material on belt: Reduce impact by improving chute design; Install impact idlers.

10. Excessive top cover wear, uniform around belt.

• 1. Dirty stuck, or misaligned return rollers: Remove accumulations; Install cleaning devices, use self-cleaning return rollers, and improve maintenance and lubrication.
• 2. Cover quality too low: Replace with the belt of heavier cover gauge or higher quality rubber.
• 3. Material spillage and buildup: Improve loading and transfer conditions; Install cleaning devices; Improve maintenance.
• 4. Off-center loading or poor loading: Adjust the chute to place the load on the center of the belt; Discharge material in the direction of belt travel at or near belt speed.
• 5. Excessive sag between idlers causing the load to walk and shuffle on the belt as it passes over idlers: Increase tension if unnecessarily low; reduce idler spacing.

11. Severe pulley cover wear.

• 1. Sticking idlers: Free idlers and improve maintenance and lubrication.
• 2. Slippage on drive pulley: Increase tension through screw take-up or add counterweight; lagging drive pulley: Increase arc of contact.
• 3. Material spillage and buildup: Improve loading and transfer conditions; Install cleaning devices; Improve maintenance.
• 4. Material trapped between belt and pulley; Install plows or scrapers on return run ahead of tail pulley.
• 5. Bolt heads protruding above lagging: Tighten bolts: Replace lagging: Use vulcanized-on lagging.
• 6. Excessive forward tilt of trough idlers: Reduce forward tilt of idlers to no more than 2°from vertical.

12. Longitudinal grooving or cracking of bottom cover

• 1. Sticking idlers: Free idlers and improve maintenance and lubrication.
• 2. Material spillage and buildup: Improve loading and transfer conditions; Install cleaning devices; Improve maintenance.
• 3. Slippage on drive pulley: Increase tension through screw take-up or add counterweight; lagging drive pulley; Increase arc of contact.
• 4. Pulley lagging worn: Replace pulley lagging.

13. Covers harden or crack

• 1. Heat or chemical damage: Use a belt designed for specific conditions.
• 2. Improper storage or handling: Refer to ISO 5285-2004; Consult Marsbelts.

14. Cover swells in spots or streaks.

• 1. Spilled oil or grease,over-lubrication of idlers: Improve housekeeping; Reduce the quantity of grease used; Check grease seals.

15. Belt breaks at or behind fasteners; Fasteners pull out.

• 1. Fastener plates too long for pulley size: Replace with smaller fasteners; Increase pulley size.
• 2. Wrong type of fastener, fasteners too tight or too loose: Use proper fasteners and splice technique; Set up Schedule for regular fastener inspection.
• 3. Tension too high: Increase speed, same tonnage; Reduce tonnage, same speed; Reduce friction with better maintenance and replacement of damaged idlers; Decrease tension by increasing arc of contact or go to lagged pulley; Reduce CWT to minimum amount.
• 4. Heat or chemical damage: Use a belt designed for specific conditions.

16. Vulcanized splice separation.

• 1. Belt improperly spliced: Re-splice using a proper method as recommended by Marsbelts.
• 2. Pulleys too small: Use larger diameter pulleys.
• 3. Tension too high: Increase speed, same tonnage; Reduce tonnage, same speed; Reduce friction with better maintenance and replacement of damaged idlers; Decrease tension by increasing arc of contact or go to lagged pulley; Reduce CWT to minimum amount.
• 4. Material trapped between belt and pulley; Install plows or scrapers on return run ahead of tail pulley.
• 5. The improper transition between the troughed belt and terminal pulleys: Refer to DIN 22131:Adjust transition under belt standard; Consult Marsbelts.

17. Excessive edge wear, broken edges.

• 1. Off-center loading or poor loading: Adjust the chute to place the load on the center of the belt; Discharge material in the direction of belt travel at or near belt speed.
• 2. Material spillage and buildup: Improve loading and transfer conditions; Install cleaning devices; Improve maintenance.
• 3. Belt hitting structure: Install training idlers on carrying and return runs.
• 4. Bowed belt: For new belts, this condition should disappear during break-in; In rare instances belt must be straightened or replaced: Check storage and handling of belt rolls.

18. Transverse breaks at belt edge.

• 1. Belt edges folding up on structure; Same corrections as for ①②③( ①.Idlers or pulleys out of square with the center line of belt: Readjust idlers in the affected area. ②.Conveyor frame or structure crooked: Straighten in the affected area. ③.Idler frame not centered on belt: Readjust idlers in the affected area.): Install limit switches; Provide more clearance.
• 2. Improper transition between the troughed belt and terminal pulleys: Refer to DIN 22131:Adjust transition under belt standard: Consult Marsbelts.
• 3. Severe convex (hump)vertical curve: Decrease idler spacing in curve: Increase curve radius; Consult Marsbelts.

19. Short breaks in carcass parallel to belt edge, star breaks in carcass

• 1. Impact of material on belt: Reduce impact by improving chute design; Install impact idlers.
• 2. Material trapped between belt and pulley; Install plows or scrapers on return run ahead of tail pulley.

20. Ply separation.

• 1. Insufficient transverse stiffness: Replace with the proper belt.
• 2. Pulleys too small: Use larger diameter pulleys.
• 3. Heat or chemical damage: Use a belt designed for specific conditions.

21. Carcass fatigue at idler junction

• 1. Improper transition between the troughed belt and terminal pulleys: Refer to DIN 22131:Adjust transition under belt standard; Consult Marsbelts.
• 2. Severe convex (hump)vertical curve: Decrease idler spacing in curve: Increase curve radius; Consult Marsbelts.
• 3. Excessive forward tilt of trough idlers: Reduce forward tilt of idlers to no more than 2°from vertical.
• 4. Belt improperly spliced: Re-splice using a proper method as recommended by Marsbelts.
• 5. Insufficient transverse stiffness: Replace with the proper belt.
• 6. Excessive sag between idlers causing the load to walk and shuffle on the belt as it passes over idlers: Increase tension if unnecessarily low; reduce idler spacing.

22. Cover blisters or sand blisters.

• 1. Cover cuts or very small cover away from carcass: Make spot repair with vulcanization or self-curing repair material.
• 2. Spilled oil or grease,over-lubrication of idlers: Improve housekeeping; Reduce the quantity of grease used; Check grease seals.

23. Belt cupping-new belt

• 1. Excessive cover gauge ratio: DIN 22101 section 10.3 recommends the ratio to be≤3. Use a belt with a lower gauge ratio and/or a thicker carcass.

24. Belt cupping-old belt (was OK when new).

• 1. Spilled oil or grease,over-lubrication of idlers: Improve housekeeping; Reduce the quantity of grease used; Check grease seals.
• 2. Heat or chemical damage: Use a belt designed for specific conditions.